U.S. patent application number 10/442676 was filed with the patent office on 2004-01-08 for automatic mixing and dilution methods and apparatus for online characterization of equilibrium and non-equilibrium properties of solutions containing polymers and/or colloids.
Invention is credited to Reed, Wayne F..
Application Number | 20040004717 10/442676 |
Document ID | / |
Family ID | 33489325 |
Filed Date | 2004-01-08 |
United States Patent
Application |
20040004717 |
Kind Code |
A1 |
Reed, Wayne F. |
January 8, 2004 |
Automatic mixing and dilution methods and apparatus for online
characterization of equilibrium and non-equilibrium properties of
solutions containing polymers and/or colloids
Abstract
A method involving the automatic, online dilution of polymer
and/or colloid solutions, such that, when the diluted polymer
stream flows through suitable detectors, non-equilibrium processes,
such as polymerization, degradation and aggregation, can be
monitored. The dilution involves a reacting or stock solution of
polymer and/or colloid, and at least one solvent. The online
dilution technique can also be used to assess the effects of
solvent quality and other solutes on polymer/colloid
characteristics and reactions, and also permits equilibrium
characterization of polymers/colloids by making a single stock
solution of the polymer/colloid. A device is developed that is
capable of automatically and continuously extracting fluid from a
polymer-containing vessel and mixing this with a solvent such that
the final fluid is dilute enough that single particle light
scattering, spectrophotometric and other measurements can be made
on it. Whereas many sampling and dilution devices exist, the
novelty of this invention consists in its ability to deal with very
high viscosities, including those laden with bubbles, and to
introduce only a short delay time between sampling and measurement.
The device is ideally suited for situations where the viscosity of
the polymer-containing vessel changes over a wide range during the
course of a reaction; e.g. polymerization, polymer degradation,
aggregation, and others. Furthermore, provision is made for modular
conditioning stages, such as changing solvent conditions,
evaporating monomer, filtering, etc. The amount of sample actually
withdrawn for measurement is very low, normally on the order of
0.25 ml to 5 ml per hour. The device can also vary the dilution
factor either automatically or manually during operation.
Inventors: |
Reed, Wayne F.; (New
Orleans, LA) |
Correspondence
Address: |
GARVEY SMITH NEHRBASS & DOODY, LLC
THREE LAKEWAY CENTER
3838 NORTH CAUSEWAY BLVD., SUITE 3290
METAIRIE
LA
70002
|
Family ID: |
33489325 |
Appl. No.: |
10/442676 |
Filed: |
May 21, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10442676 |
May 21, 2003 |
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09404484 |
Sep 23, 1999 |
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09404484 |
Sep 23, 1999 |
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08969386 |
Nov 13, 1997 |
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6052184 |
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10442676 |
May 21, 2003 |
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09690099 |
Oct 16, 2000 |
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6618144 |
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60031095 |
Nov 13, 1996 |
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60159839 |
Oct 15, 1999 |
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60382213 |
May 21, 2002 |
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Current U.S.
Class: |
356/338 |
Current CPC
Class: |
G01N 15/14 20130101;
G01N 15/1434 20130101; G01N 30/02 20130101; G01N 2021/513 20130101;
G01N 2021/4711 20130101; G01N 2015/0693 20130101; G01N 35/08
20130101; G01N 30/74 20130101; G01N 2015/025 20130101; G01N
2021/4716 20130101; G01N 21/49 20130101; G01N 15/0211 20130101;
G01N 2015/0092 20130101; G01N 35/085 20130101; G01N 2011/0046
20130101; G01N 2015/0216 20130101; G01N 21/51 20130101; G01N
35/1097 20130101; G01N 2201/0218 20130101; G01N 21/53 20130101;
G01N 2021/4719 20130101; G01N 30/02 20130101; B01D 15/34
20130101 |
Class at
Publication: |
356/338 |
International
Class: |
G01N 021/00 |
Claims
1. Apparatus for static light scattering for absolute
macromolecular characterization, comprising: a submersible probe
for use with at least one photodetector and a computer
electronically connected to the photodetector, the computer being
programmed for analyzing data from static light scattering for
performing absolute macromolecular characterization, the probe
being submersible in a fluid to be sampled, the probe comprising: a
light source; light detection means secured in a fixed position
relative to the light source; transmission means for transmitting
light from the light detection means to the photodetector, the
transmission means being of a sufficient length and flexibility to
allow the submersible probe to be submersed in the fluid to be
sampled without submersing the photodetector.
2. The apparatus of claim 1, further comprising the photodetector
and the computer.
3. The apparatus of claim 1, comprising a plurality of
photodetectors.
4. The apparatus of claim 1, wherein the probe comprises: a ring
member having a channel into which sample fluid enters upon
immersion; means for securing the light source in the ring member;
and means for securing the light detection means in the ring
member.
5. The apparatus of claim 4, wherein the ring member includes a
beam dump.
6. The apparatus of claim 4, wherein the ring member is made of an
opaque material.
7. The apparatus of claim 1, wherein the light detection means
comprises fiber optic light conduits.
8. The apparatus of claim 1, further comprising means for removably
attaching the light transmission means to the photodetector.
9. The apparatus of claim 1, further comprising a harness for
securing the light transmission means to minimize damage to the
light transmission means.
10. The apparatus of claim 2, wherein the size range of
detectability is about 20 Angstroms to about 100 microns.
11. The apparatus of claim 2, wherein the detectable range of
particles is from about 500 g/mole to about 10.sup.14 g/mole.
12. Apparatus for static light scattering, comprising: a
submersible probe for use with at least one photodetector and a
computer electronically connected to the photodetector, the
computer being programmed for analyzing data from static light
scattering for performing characterization of a fluid, the probe
being submersible in a fluid to be sampled, the probe comprising: a
ring member; a light source secured in the ring member; light
detection means secured in the ring member in a fixed position
relative to the light source; transmission means for transmitting
light from the light detection means to the photodetector, the
transmission means being of a sufficient length and flexibility to
allow the submersible probe to be submersed in the fluid to be
sampled without submersing the photodetector.
13. The apparatus of claim 12, further comprising the photodetector
and the computer.
14. The apparatus of claim 12, comprising a plurality of
photodetectors.
15. The apparatus of claim 12, wherein the probe comprises: a ring
member having a channel into which sample fluid enters; means for
securing the light source in the ring member; and means for
securing the light detection means in the ring member.
16. The apparatus of claim 15, wherein the ring member includes a
beam dump.
17. The apparatus of claim 15, wherein the ring member is made of
an opaque material.
18. The apparatus of claim 12, wherein the light detection means
comprises fiber optic light conduits.
19. The apparatus of claim 12, further comprising means for
removably attaching the light transmission means to the
photodetector.
20. The apparatus of claim 12, further comprising a harness for
securing the light transmission means to minimize damage to the
light transmission means.
21. The apparatus of claim 13, wherein the size range of
detectability is about 20 Angstroms to about 100 microns.
22. The apparatus of claim 13, wherein the detectable range of
particles is from about 500 g/mole to about 10.sup.14 g/mole.
23. Apparatus for static light scattering, comprising: a plurality
of interchangeable probes for use with at least one light detector
and a computer electronically connected to the photodetector, the
computer being programmed for analyzing data from static light
scattering for performing characterization of a fluid, each probe
comprising: a ring member; a light source secured in the ring
member; light detection means secured in the ring member in a fixed
position relative to the light source; transmission means for
transmitting light from the light detection means; and means for
removably connecting the transmission means to the
photodetector.
24. The apparatus of claim 23, wherein the transmission means
allows the probe to move relative to the photodetector when the
transmission means is connected to the photodetector.
25. The apparatus of claim 23, further comprising the photodetector
and the computer.
26. The apparatus of claim 23, wherein at least one of the probes
is submersible.
27. The apparatus of claim 23, wherein at least one of the probes
has connectors to allow fluid conduits to be attached thereto.
28. The apparatus of claim 23, wherein at least one of the probes
has a receptacle for holding sample fluid.
29. The apparatus of claim 23, wherein at least one of the probes
has means for receiving a receptacle for holding sample fluid.
30. The apparatus of claim 23, wherein at least one of the probes
has a handle.
31. A method of performing absolute macromolecular characterization
with static light scattering using the apparatus of claim 1, the
method comprising: submersing the probe of claim 1 in a sample
fluid; optically connecting the probe of claim 1 with a
photodetector, the photodetector being electronically connected to
a computer, the computer being programmed for analyzing data from
static light scattering for performing absolute macromolecular
characterization, the probe being submersible in a fluid to be
sampled; using the computer, analyzing data from static light
scattering for performing absolute macromolecular characterization
of the sample fluid in which the probe is submersed.
32. A method of performing absolute macromolecular characterization
with static light scattering, the method comprising: optically
contacting a probe with a sample fluid containing a substance being
studied, the probe having a scattering volume containing a small
enough number of large scattering particles to not prevent absolute
macromolecular characterization of the substance being studied;
optically connecting the probe to a photodetector, the
photodetector being electronically connected to a computer with an
interface, the computer being programmed for analyzing data from
static light scattering for performing absolute macromolecular
characterization; using the computer, analyzing data from static
light scattering for performing absolute macromolecular
characterization of the sample fluid in optical contact with the
probe, while electronically separating out scattering bursts from
large scattering particles in the sample fluid, allowing hence the
large scattering particles to also be counted and characterized,
wherein: the photodetector and the interface operate at a rate fast
enough to electronically resolve the bursts.
33. The method of claim 32, wherein the rate is at least 2 Hz.
34. The method of claim 32, wherein the number of large scattering
particles is less than 100 per scattering volume.
35. The method of claim 32, further comprising the step of counting
and characterizing the large scattering particles.
36. A method of conducting absolute macromolecular characterization
in real time in a polymerization reaction, comprising: (a) diluting
a sample fluid to be sampled to a concentration of such that
interparticle effects do not dominate the scattering behavior; (b)
irradiating the diluted sample fluid with incident light; (c)
measuring light scattered from the diluted sample fluid with at
least one photodetector and a computer electronically connected to
the photodetector, the computer being programmed for analyzing data
from static light scattering for performing absolute macromolecular
characterization.
37. The method of claim 36, wherein light is transmitted from the
diluted sample fluid to the photodetector with a submersible probe
comprising: a light source for providing the incident light; light
detection means secured in a fixed position relative to the light
source; and transmission means for transmitting light from the
light detection means to the photodetector, the transmission means
being of a sufficient length and flexibility to allow the
submersible probe to be submersed in the fluid to be sampled
without submersing the photodetector.
38. The method of claim 36, wherein the dimensionless quantity
2A.sub.2cM.sub.w is not greater than 10.
39. The method of claim 36, wherein the dimensionless quantity
2A.sub.2cM.sub.w is not greater than 2.
40. The method of claim 36, wherein the photodetector has a
scattering volume containing a small enough number of large
scattering particles to not prevent absolute macromolecular
characterization of the substance being studied; using the
computer, analyzing data from static light scattering for
performing absolute macromolecular characterization of the sample
fluid in optical contact with the probe, while electronically
separating out scattering bursts from large scattering particles in
the sample fluid, allowing hence the large scattering particles to
also be counted and characterized, wherein: the photodetector and
the interface operate at a rate fast enough to electronically
resolve the bursts.
41. Apparatus for static light scattering for absolute
macromolecular characterization, comprising: a probe for use with
at least one photodetector and a computer electronically connected
to the photodetector, the computer being programmed for analyzing
data from static light scattering for performing absolute
macromolecular characterization, the probe comprising: a light
source; light detection means secured in a fixed position relative
to the light source; transmission means for transmitting light from
the light detection means to the photodetector, the transmission
means being of a sufficient length and flexibility to allow the
probe to be used remote from the photodetector.
42. The apparatus of claim 41, wherein transmission means is 6
inches-100 feet long.
43. Apparatus for static light scattering, comprising: an
interchangeable probe for use with at least one light detector and
a computer electronically connected to the photodetector, the
computer being programmed for analyzing data from static light
scattering for performing characterization of a fluid, the probe
comprising: a ring member; a light source secured in the ring
member; light detection means secured in the ring member in a fixed
position relative to the light source; transmission means for
transmitting light from the light detection means; and means for
removably connecting the transmission means to the
photodetector.
44. The apparatus of claim 43, wherein the transmission means
allows the probe to move relative to the photodetector when the
transmission means is connected to the photodetector.
45. The apparatus of claim 43, further comprising the photodetector
and the computer.
46. The apparatus of claim 43, wherein the probe is
submersible.
47. The apparatus of claim 43, wherein the probe has connectors to
allow fluid conduits to be attached thereto.
48. The apparatus of claim 43, wherein the probe has a receptacle
for holding sample fluid.
49. The apparatus of claim 43, wherein the probe has means for
receiving a receptacle for holding sample fluid.
50. The apparatus of claim 43, wherein the probe has a handle.
51. The apparatus of claim 43, wherein the light detection means
are placed at scattering angles of from about 10.degree. to about
170.degree..
52. The apparatus of claim 43, wherein the ring member includes a
beam dump.
53. The apparatus of claim 43, wherein the ring member is made of
an opaque material.
54. The apparatus of claim 43, wherein the transmission means is of
a sufficient length and flexibility to allow the probe to be used
remote from the photodetector.
55. The apparatus of claim 43, further comprising means for using
the apparatus for absolute macromolecular characterization.
56. The apparatus of claim 55, further comprising means for
counting particles simultaneously.
57. The apparatus of claim 43, wherein the ring member contains a
sampling cavity that can be directly contacted with sample fluid,
which cavity can hold sample fluid which is introduced via flow,
pipeting, immersion or other means, and which fluid can either
remain stationary in the ring or flow through it.
58. The apparatus of claim 23, further comprising a plurality of
photodetectors.
59. The method of claim 36, wherein the diluting of the sample
fluid occurs on-line.
60. The method of claim 59, wherein the dimensionless quantity
2A2cMw is not greater than 2.
61. A method of making a real-time measurement of a reaction,
interaction or process occurring in a solution containing polymers
and/or colloids, comprising: (a) automatically diluting and/or
mixing online at least two separate solutions, at least a first
solution containing polymers and/or colloids and at least a second
solution containing a solvent or a solution containing other types
of polymers and/or colloids, to create a diluted and/or mixed
solution; (b) measuring characteristics of the diluted and/or mixed
solution; (c) determining from the measurements made in step (b)
characteristics of the reaction, interaction or process occurring
in first solution containing polymers and/or colloids.
62. The method of claim 61, wherein at least three solutions are
mixed together.
63. The method of claim 61, wherein a light scattering detector is
used to determine the relative molecular mass of a polymer during a
polymerization reaction.
64. The method of claim 61, wherein a suitable concentration
detector is used to simultaneously measure the concentration of
solutes in the mixed solution.
65. The method of claim 61, further comprising using a light
scattering detector to determine, online, the absolute weight
averaged molecular mass Mw of a polymer as it is produced in a
polymerization reaction.
66. The method of claim 65, wherein a flow type viscometer is
placed inline, so that reduced viscosity can be determined
simultaneously with Mw, and a measure of polydispersity can hence
be formed, online, by combining the values of reduced viscosity and
Mw.
67. The method of claim 61, wherein a light scattering detector is
used to monitor the relative degradation of a polymer solution
caused by enzymes or other chemical agents, radiation, or heat.
68. The method of claim 67, wherein the absolute Mw of the
degrading polymer solution is monitored.
69. The method of claim 68, wherein a concentration detector is
also used to monitor the absolute Mw of the degrading polymer
solution.
70. The method of claim 63, wherein the first and second solutions
can interact at certain concentrations, and the interaction is
detected online by the light scattering detector.
71. The method of claim 70, wherein the Mw of the interacting
species is measured online.
72. The method of claim 71, wherein a concentration detector is
also used to measure the Mw of the interacting species online.
73. The method of claim 70, wherein a viscometric detector is used
to measure online changes in relative viscosity due to
interactions.
74. The method of claim 71, wherein a viscometric detector is used
to determine online the reduced viscosity.
75. The method of claim 72, wherein a viscometric detector is used
to determine online the reduced viscosity.
76. The method of claim 63, wherein the first and second solutions
can interact at certain concentrations, and the interaction is
detected online by a turbidity sensing device.
77. The method of claim 61 wherein HTDSLS is used to recognize and
characterize large scattering particles in the diluted and/or mixed
solution, whether such particles be impurities or integral
components of the polymer/colloid solution being characterized.
78. The method of claim 62, wherein: the polymer/colloid
concentration in the diluted and/or mixed solution is held
constant, the second solution contains a solvent and is produced by
mixing of two or more additional reservoirs and is made to vary,
and the effects of the second solution on the polymers/colloids is
measured online.
79. The method of claim 61, wherein: the online dilution is used to
dilute a polymer/colloid solution, and absolute macromolecular
characterization is performed using light scattering and
concentration detectors.
80. The method of claim 79, further comprising using a viscometric
detector to detect viscosity.
81. Apparatus including a device capable of automatically and
continuously diluting and/or mixing a high viscosity fluid in at
least two stages, wherein a first mixing of the high viscosity
fluid and a diluent occurs to create a first mixed stream, and at
least a second mixing occurs in which the first mixed solution is
mixed with a diluent or diluents in one or more stages to create a
mixed stream for measurement.
82. The apparatus of claim 81, wherein the fluid ranges in
viscosity from 50 to 5,000,000 cP.
83. The apparatus of claim 81, wherein the viscosity of the fluid
increases from less than 1 cP to over 5,000,000 cP during the
course of a reaction, or decreases from over 5,000,000 cP to less
than 1 cP.
84. The apparatus of claim 83, wherein the viscosity change occurs
over an interval of no less than a minute and not more than 48
hours.
85. The apparatus of any one of claims 81-84, wherein the relative
viscosity of the fluid increases anywhere from a factor of around
300 to a factor of around 10,000,000.
86. The apparatus of any one of claims 81-85, wherein the dilution
factor is in the range of around 2 to 50,000.
87. The apparatus of any one of claims 81-86, wherein the diluted
or mixed material is continuously withdrawn for analysis at a rate
ranging from around 0.001 to 1000 ml/minute.
88. The apparatus of any one of claims 81-87, wherein the diluted
or mixed material flows through a train of detectors in order to
analyze the contents of the vessel containing the viscous
liquid.
89. The apparatus of any one of claims 81-88, wherein the high
viscosity fluid is contained in a polymerization reactor.
90. The apparatus of any one of claims 81-89, wherein the vessel
containing the high viscosity fluid is a fermentation reactor.
91. The apparatus of any one of claims 81-90, wherein the high
viscosity fluid is a biological or bioactive polymer, such as a
protein, polysaccharide, pharmaceutical agent, etc.
92. The apparatus of any one of claims 81-91, further comprising a
light scattering detector for analysis of the mixed stream for
measurement.
93. The apparatus of any one of claims 81-92, further comprising a
concentration detector for analysis of the mixed stream for
measurement.
94. The apparatus of claim 93, wherein the concentration detector
is from the group consisting of an ultraviolet/visible
spectrometer, a refractometer, and an evaporative light scattering
device.
95. The apparatus of any one of claims 81-94, further comprising a
viscometer for analysis of the mixed stream for measurement.
96. The apparatus of any one of claims 81-95, further comprising a
near infra-red detector for analysis of the mixed stream for
measurement.
97. The apparatus of any one of claims 81-96, further comprising a
solution conductivity detector for analysis of the mixed stream for
measurement.
98. The apparatus of any one of claims 81-97, further comprising a
primary pump and a liquid containing vessel containing high
viscosity fluid, and wherein the primary pump of the device
recirculates viscous liquid to the liquid containing vessel, and a
fraction of this recirculating flow is diverted, either
continuously, or at intervals, for mixing or diluting.
99. The apparatus of any one of claims 81-98, wherein the mixing or
diluting of the viscous liquid takes place in a low pressure mixing
chamber.
100. The apparatus of any one of claims 81-99, further comprising
detectors and debubbling means, wherein any bubbles are exhaled in
a mixing/diluting stage and are absent in the mixed stream for
measurement reaching the detectors.
101. The apparatus of any one of claims 81-100, including an inlet
and an outlet, and further comprising at least one sample
conditioning stage between the inlet and outlet.
102. The apparatus of claim 101, wherein there are a plurality of
sample conditioning stages between the inlet and outlet.
103. The apparatus of any one of claims 81-102, wherein the mixed
stream for measurement is dilute enough to enable useful
measurements to be taken by at least one measuring device from the
group consisting of a light scattering detector, a concentration
detector, an ultraviolet/visible spectrometer, a refractometer, an
evaporative light scattering device, a viscometer, and a
conductivity detector.
104. The apparatus of any one of claims 81-102, wherein the
dilution factor can be held constant, or can be varied either
manually or automatically during use.
105. The apparatus of any one of claims 81-104, wherein a
microprocessor-containing device (e.g. a microcomputer) is used to
control one or more pumps, such that the dilution factor and/or
detector feed flow rate can be automatically controlled.
106. A method of automatically and continuously diluting and/or
mixing high viscosity fluids comprising using the apparatus of any
one of claims 81-105.
107. The invention of any one of claims 81-106, wherein the
relative viscosity of the fluid increases or decreases from a
factor of 1,000 to a factor of 100,000.
108. The invention of any one of claims 81-106, wherein the
relative viscosity of the fluid increases or decreases a factor of
at least 100.
109. The invention of any one of claims 81-106, wherein the
relative viscosity of the fluid increases or decreases a factor of
at least 500.
110. The invention of any one of claims 81-106, wherein the
relative viscosity of the fluid increases or decreases a factor of
at least 1,000.
111. The invention of any one of claims 81-106, wherein the
relative viscosity of the fluid increases or decreases a factor of
at least 5,000.
112. The invention of any one of claims 81-106, wherein the
relative viscosity of the fluid increases or decreases a factor of
at least 50,000.
113. The invention of any one of claims 81-106, wherein the
relative viscosity of the fluid increases or decreases a factor of
at least 500,000.
114. The invention of any one of claims 81-113, wherein at least
two mixing stages occur after the first mixed stream is
created.
115. The invention of any one of claims 81-113, wherein at least
three mixing stages occur after the first mixed stream is
created.
116. The invention of any one of claims 81-113, wherein at least
four mixing stages occur after the first mixed stream is
created.
117. The invention of any one of claims 81-113, wherein at least
five mixing stages occur after the first mixed stream is
created.
118. The inventions substantially as shown and described herein.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part of my co-pending U.S. patent
application Ser. No. 09/404,484, filed 23 Sep. 1999, which is a
continuation-in-part of U.S. patent application Ser. No.
08/969,386, filed Nov. 13, 1997, now U.S. Pat. No. 6,052,184.
[0002] This is also a continuation-in-part of my co-pending U.S.
patent application Ser. No. 09/690,099, filed 16 Oct. 2000.
[0003] Priority of my U.S. Provisional Patent Application Serial
No. 60/031,095, filed 13 Nov. 1996, incorporated herein by
reference, is hereby claimed. Priority of my U.S. Provisional
Patent Application Serial No. 60/159,839, filed 15 Oct. 1999,
incorporated herein by reference, is hereby claimed. Priority of my
U.S. Provisional Patent Application Serial No. 60/382,213, filed 21
May 2002, incorporated herein by reference, is hereby claimed.
[0004] My International Publication No. WO 01/29534 A1 is
incorporated herein by reference.
[0005] All of my patents and patent applications mentioned herein
are incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0006] Not applicable
REFERENCE TO A "MICROFICHE APPENDIX"
[0007] Not applicable
BACKGROUND OF THE INVENTION
[0008] 1. Field of the Invention
[0009] The present invention relates to the absolute
characterization of microscopic particles in solution. More
particularly, the present invention relates to the absolute
characterization of microscopic particles, such as polymers and
colloids using static light scattering (SLS) and time-dependent
static light scattering (TDSLS). In principle, the size range of
detectability should run from about 20 Angstroms to 100 microns,
with useful measurability in the range from 20 Angstroms to 2
microns, and a preferred range from about 20 Angstroms to 5000
Angstroms. Stated in terms of molar mass, the detectable range of
particles should run from about 500 g/mole to 10.sup.14 g/mole,
with useful measurability in the range of 500 g/mole to 10.sup.9
g/mole, with a preferred range from about 1000 g/mole to 10.sup.7
g/mole.
[0010] The preferred use of this invention is the determination of
average particle masses, static dimensions, interaction
coefficients, and other properties, as well as their changes in
time, when scattering is from a very large number of particles.
This is to be distinguished from turbidometric and nephelometric
techniques, in which turbidity or relative scattering of solutions
is measured and compared to relative reference solutions, in order
to obtain concentrations of particles. The SLS technique employed
refers to absolute macromolecular characterization, and not to
determinations of concentrations of particulates with respect to
specific relative calibrations, etc. This is also to be
distinguished from devices which count and characterize single
particles, although the present invention can count and
characterize single particles, in addition to making SLS
measurements. The least number of particles whose scattered light
would be detected in the scattering volume (the volume of
illuminated sample whose scattering is measured by a given
photodetector) would be on the order of 20 and the maximum on the
order of 4.times.10.sup.17, with the preferred range being from
about 15,000 to 1.5.times.10.sup.13 particles. In terms of
concentration of solute (dissolved polymer or colloid) the range
would be from about 10.sup.-8 g/cm.sup.3 (for very large particles)
to 0.2 g/cm.sup.3 (for very small particles) with the preferred
range being from about 10.sup.-6 to 10.sup.-1 g/cm.sup.3. It should
be pointed out that SLS in the absolute mode requires optically
transparent solutions in which single, not multiple, scattering
dominates. Many particle concentration detectors actually work in
turbid solutions, which is a different range of conditions
entirely.
[0011] SLS has proven to be a useful technique not only for
characterizing equilibrium properties of microscopic particles,
such as molar mass, dimensions and interactions, but also for
following time-dependent processes such as polymerization,
degradation and aggregation. Measuring the time-independent angular
distribution and absolute intensity of scattered light in the
equilibrium cases allows the former properties to be determined,
according to procedures set forth by Lord Rayleigh, Debye, Zimm and
others (e.g. ref. 1). In particular, this invention can be used in
conjunction with the well known procedure of Zimm to determine
weight average molar mass M.sub.w, z-average mean square radius of
gyration <S.sup.2>.sub.z and second virial coefficient
A.sub.2. Measuring the time-dependent changes in the scattered
intensity allows calculation of kinetic rate constants, as well as
deduction of kinetic mechanisms and particle structural features
(e.g. refs. 2,3). TDSLS can be used to monitor polymerization and
degradation reactions, aggregation, gelling and phase separation
phenomena (e.g. ref. 4).
[0012] In addition to absolute SLS and TDSLS measurements, the
present invention can also simultaneously count and characterize
individual particles which are much larger than the principal
polymer or colloid particles; e.g., the large particles may have a
radius of 5 microns, whereas the polymer may have an effective
radius of 0.1 micron. The large particles may represent a
contaminant or impurity, or may be an integral part of the
solution, e.g., bacteria (large particles) produce a desired
polymer (e.g., a polysaccharide) in a biotechnology reactor. The
number density of bacteria can be followed in time, and the
absolute macromolecular characterization of the polysaccharide
could also be made (an auxiliary concentration detector would also
be necessary if the polysaccharide concentration changes in
time).
[0013] The present invention involves automatic online mixing
and/or dilution of solutions containing polymers and/or colloids in
order to provide relative and/or absolute characterization of these
microscopic particles in solution. In the following, the term
`dilution` will be used, because, whenever two or more solutions
are mixed, as described herein, the solutes in each will become
dilute. The automatic dilution is intended to replace the
traditional prior art of manually diluting such polymer/colloid
solutions in order to make characterizing measurements, and to
extend measurement capabilities to novel situations, especially
those involving non-equilibrium (that is, time-dependent)
processes, such as polymerization, degradation, aggregation and
phase separation. The method can be used in conjunction with a
variety of detectors, such as static light scattering (SLS),
time-dependent static light scattering (TDSLS), heterogeneous time
dependent light scattering (HTDSLS), dynamic light scattering,
refractometry, ultraviolet and visible spectrophotometry,
turbidometry, nephelometry, viscometry and evaporative light
scattering. The automatic, online dilution of polymer and/or
colloid solutions will be shown to have broad applicability in many
sectors. In referring to the ensemble of SLS, TDSLS and HTDSLS
detectors and methods in the following, the term light scattering
(LS) will be used for brevity.
[0014] In principle, the size range of detectability of the
polymers and/or colloids should run from about 20 Angstroms to 100
microns, with useful measurability in the range from 20 Angstroms
to 20 microns, and a preferred range from about 20 Angstroms to
5000 Angstroms. Stated in terms of molar mass, the detectable range
of particle molar masses should run from about 500 g/mole to 1014
g/mole, with useful measurability in the range of 500 g/mole to
1011 g/mole, with a preferred range from about 1000 g/mole to 1010
g/mole.
[0015] This invention focuses on automated methods that are used to
characterize equilibrium and non-equilibrium properties of
solutions containing polymers and/or colloid particles.
Characterization of polymers and colloids via LS detectors is in
terms of average particle masses, static dimensions, interaction
coefficients, and other properties, as well as their changes in
time, when scattering is from a very large number of particles.
When large colloidal particles are present, the use of the method
in conjunction with HTDSLS also allows the determination of the
number density of these particles, information on their dimensions,
and, when the system is not in equilibrium, how these properties
change in time.
[0016] SLS has proven to be a useful technique for characterizing
equilibrium properties of microscopic particles, such as molar
mass, dimensions and interactions, and TDSLS and HTDSLS for
following time-dependent processes such as polymerization,
degradation and aggregation. Measuring the time-independent angular
distribution and absolute intensity of scattered light in the
equilibrium cases allows the former properties to be determined,
according to procedures set forth by Lord Rayleigh, Debye, Zimm and
others (e.g. ref. 1). In particular, this invention can be used in
conjunction with the well known procedure of Zimm to determine
weight average molar mass Mw, z-average mean square radius of
gyration <S2>z and second virial coefficient A2. Measuring
the time-dependent changes in the scattered intensity allows
calculation of kinetic rate constants, as well as deduction of
kinetic mechanisms and particle structural features (e.g. refs.
2,3). TDSLS can be used to monitor polymerization and degradation
reactions, aggregation, gelling and phase separation phenomena
(e.g. ref. 4).
[0017] In addition to absolute SLS and TDSLS measurements, use of
the present invention in conjunction with HTDSLS allows
simultaneous counting and characterization of individual particles
which are much larger than the principal polymer or colloid
particles; e.g., the large particles may have a radius of 5
microns, whereas the polymer may have an effective radius of 0.1
micron. The large particles may represent a contaminant or an
impurity, or may be an integral part of the solution, e.g.,
bacteria (large particles) produce a desired polymer (e.g., a
polysaccharide) in a biotechnology reactor. The number density of
bacteria can be followed in time, and the absolute macromolecular
characterization of the polysaccharide could also be made (an
auxiliary concentration detector would also be useful if the
polysaccharide concentration changes in time).
[0018] The method whereby simultaneous, absolute characterization
of polymers and number counting of large particles is carried out,
is described in U.S. patent application Ser. No. 08/969,386. To
optimize the technique, one should make the sample liquid flow
relative to the irradiating laser beam (or other light source) in
the scattering chamber, so as to produce countable scattering
spikes as each large particle passes through the detected portion
of the illuminated volume (the `scattering volume`), while
ensuring, via correct design of the optical and electronic
detection system, that there is on the average less than one large
particle in the scattering volume at any given time. This allows
the scattering level to recover to the baseline scattering of the
pure polymer between the scattering spikes due to the large
particles, so that the polymer can be absolutely characterized. The
fraction of baseline time termed herein `clear window time`, and is
detailed mathematically in ref 5, wherein the method has recently
been demonstrated. In this demonstration, it was first shown that
useful characterization of a polymer solution could be made even in
the presence of a large amount of particulate contamination. The
contaminant was a known amount of 2 micron latex spheres introduced
in increasing amounts to an aqueous polymer solution containing the
polymer poly(vinyl pyrrolidone), or PVP. Secondly, the ability to
simultaneously make absolute characterization of the polymer while
the change in time of the large particle population was monitored
was demonstrated by monitoring the growth of E. Coli bacteria
amidst an aqueous solution of PVP polymer.
[0019] The present invention also involves the automatic extraction
and dilution of high viscosity fluids.
[0020] More particularly, the present invention also includes a
device for automatically and continuously sampling and diluting
liquids of high viscosity, normally containing synthetic and/or
biological polymers, to such an extent that absolute light
scattering and/or other optical and physical measurements can be
made. In many cases the viscosity in the vessel containing the
fluid will vary continuously from a low value to a high value
(polymerization reaction), or vice versa (degradation or phase
separation reaction). In some instances it will be desirable to
manually or automatically change the dilution factor during the
course of a reaction or monitoring process.
[0021] 2. General Background of the Invention
[0022] There is currently considerable interest in the polymer
industry for finding a means of monitoring and controlling, in
real-time or near real-time, the progress of polymerization and
other reactions. Here, `polymer industry` is understood to mean all
industries producing synthetic polymers (e.g. polyolefins), as well
as those producing or modifying biological or bioactive polymers,
whether for food, pharmaceutical, cosmetic, or other applications.
`Polymer reaction` is understood to mean polymerization,
copolymerization, degradation, or any means of modifying the
chemical or physical properties of polymers.
[0023] Currently, the state of the polymer reaction can be found by
manually sampling the reactor and making any number of analytical
tests on the contents. This, however, leads to long delay times in
obtaining results, usually too long to make useful adjustments to
the reaction. Often times the analytical laboratory facilities are
located remotely from the reactor. Such manual sampling also does
not yield a continuous enough record of the reaction to follow the
time course quantitatively. There can also be safety issues
involved when workers expose themselves to hazardous reactor
environments to obtain samples.
[0024] A step towards automation has been proposed recently by
Symyx Technologies, Inc. (Ca.) and others, wherein a discrete,
automatic sampling of reactor contents occurs, followed by
injection of a finite volume of the extracted material into an
analytical system, which contains a series of detectors, and,
optionally, a chromatographic column to perform some separation of
the injected material. This type of procedure leads to signal peaks
in the detectors each time a sample is injected. The peaks are then
normally analyzed using standard analytical practice to obtain
molecular masses, degree of monomer conversion, and, sometimes,
reduced viscosity. The actual sampling and dilution is normally
carried out by a robotic system. For example, Waters introduced
such an auto sampling system. All these techniques involve
injection of a material to produce peaks, and yield data points
separated by significant dead-times, during which the sampling and
detector system recover in preparation for the next injected pulse
of material. These techniques, including the manual one, can be
termed `discrete sampling` techniques.
[0025] The current invention builds off of an alternative sampling
and analysis method, previously introduced by this inventor. This
method is a continuous one, and does not involve injecting pulses
of material and subsequently obtaining detector peaks for analysis.
Recently, the inventor has coined the term Automatic, Continuous,
Online Monitoring of Polymerization Reactions (ACOMP) for this
method. In ACOMP a stream of material from the reactor is
continuously mixed with a solvent, and the diluted mixture flows
through the detector train, providing a continuous record of the
reaction. In ACOMP no chromatographic columns are used, finite
pulses of material are not injected into the detector train
(although they may be injected into the mixing chamber), and
detector signal peaks are not obtained.* ACOMP theory, practice and
instrumentation, and related techniques, have been extensively
described by the inventor and his
co-workers..sup.1,2,3,4,5,6,7,8,9,10,11,12,13 The single greatest
problem in the practical use of ACOMP is the automatic, continuous
preparation of the mixed or diluted sample which continuously feeds
the detector train. The problem is due chiefly to the high
viscosities which develop during many polymerization reactions, as
well as the bubbles that can occur. Commercially available mixers
are available, that use either high pressure (e.g. Dionex, Waters)
or low pressure mixing schemes (e.g. Isco). The problem with these
devices is that they are designed and built to handle only low
viscosity liquids. When one of the feeds to a low pressure mixing
pump is a reactor whose viscosity increases during a polymerization
reaction, the mixing pump is incapable of maintaining a fixed
volume withdrawal rate percentage. The result is that the lag time
between withdrawal from the reactor and arrival of the mixed
solution at the detectors becomes longer and longer as the reaction
proceeds, often times to unacceptable levels. When a high pressure
mixing scheme is used, bubbles produced either by the reaction
itself, or due to cavitation during pump withdrawal, lead to the
depriming of the withdrawal pump, and failure to continue
monitoring. The check valves and other plumbing in such pumps is
also susceptible to becoming frozen by plugs of polymeric material
that can solidify in the pumps during operation. It is apparent
that pumps that rely on pulling reactor material with a vacuum (1
atmosphere or less) are wholly unsuitable for ACOMP when
viscosities are above about 150 centipoise (cP); i.e. arrangements
of such pumps can typically follow a reaction from about 1 cP to
about 150 cP. * Another area of reaction monitoring involves in
situ probes, such as near Infra-red and rheometers. While these
probes allow real-time or near real-time data on the reaction to be
gathered, they are inevitably empirical methods, largely based on
chemometric approaches, which show a statistical relationship
between a desired polymer property and an instrument's signal.
ACOMP, in contrast, involves absolute measurements of molecular
properties.
[0026] On the other hand, a variety of pumps exist that can handle
highly viscous materials. Certain peristaltic pumps, for example
can pump liquids up to tens of thousands of cP, whereas gear, lobe
and screw pumps can move liquids of millions of cP. Whereas this
latter technology is highly developed for industries involving, for
example, plastic injection and synthetic fiber production, there is
no available system that can accomplish the prerequisite of ACOMP:
Continuously withdraw a very small flow rate of material and mix it
homogeneously with a solvent.
[0027] More information about the background of the inventions
disclosed and claimed herein can be found in my patent applications
mentioned herein.
[0028] Incorporated by reference are the following papers:
Florenzano, Strelitzki and Reed, Macromolecules, vol. 31, pp.
7226-7238, 1998, "Absolute, On-line Monitoring of Molar Mass during
Polymerization Reactions"; Strelitzki and Reed, Journal of Applied
Polymer Science, vol. 73, pp. 2359-2368, 1999, "Automated Batch
Characterization of Polymer Solutions by Static Light Scattering
and Viscometry"; Schimanowski, Strelitzki, Mullin, and Reed,
"Heterogeneous Time Dependent Static Light Scattering",
Macromolecules, (copy attached to U.S. patent application Ser. No.
09/404,484).
SUMMARY OF THE INVENTION
[0029] The present invention is the first fully submersible SLS
probe for absolute macromolecular characterization (as opposed to
particle counting, nephelometry, dynamic light scattering, or
relative concentration measurements). The optical assembly of the
present invention can be completely immersed in the scattering
medium. Thus, the present invention includes a scattering probe
which can `go into` the medium to be measured (e.g. into test
tubes, production vats, etc.), and samples of the scattering medium
need not be introduced into a transparent sample cell remote from
the medium itself, as is done in current systems. In the present
invention the probe can be submerged in a variety of harsh
environments, as concerns temperature, pressure and solvents, and
communicates to the remote electronic and signal processing portion
via a harness containing fiber optic cables.
[0030] The present invention can be used in several distinct modes
(immersion, fill mode, insert mode and flow mode), giving it wide
versatility. The probe of the present invention is not constrained
to be immersed in order to function. A small quantity of sample can
also be placed in the optical assembly compartment for measurement
in a `fill mode`. A sample in a transparent vial or cell can also
be placed in the chamber or ring member for measurement. Also, the
probe can be hooked into a flowing stream of sample liquid for use
in different applications such as polymer separation (e.g. size
exclusion chromatography), and on-line, unfractionated flows of
polymers in a vessel in equilibrium, or undergoing polymerization,
aggregation, cross-linking or degradation processes.
[0031] The present invention can respond to the needs of a wide
variety of users and applications by simply changing the
inexpensive optical assembly, since the detection, electronics,
computer interfacing and basic software are all the same. For
example, a miniature probe with a 10 microliter channel could plug
into the same `detection/analysis` back-end as a 50 milliliter
optical probe designed for immersion at high temperatures. There is
wide room for substitution of different diameter fibers with
different acceptance angles, number of photodetectors on the
`detection/analysis` back-end, etc.
[0032] The present invention does not require a transparent sample
cell for the scattering solution. Unlike all current SLS systems
for absolute macromolecular and colloidal characterization, no
glass or other transparent cell need intervene between the sample,
the detection fibers and the fiber or lens used for introducing the
incident beam. Major advantages which this confers includes
avoiding the expense, maintenance and cleaning of transparent
cells, and minimizing glare and stray light, because the optical
assembly is preferably made from a very dark or black material, and
hence does not have highly reflective glass and/or other dielectric
surfaces causing spurious glare and reflections.
[0033] The optical probe portion of the present invention is
preferably miniature in scale. Whereas other devices also use only
small sample volumes, those devices require that the sample be
pumped or injected in through appropriate plumbing. In the present
invention, when used in the fill mode, small quantities of sample
can be simply pipetted or dropped into the optical assembly
compartment, where they reside during the measurement.
[0034] The probe can achieve both absolute calibration and
self-cleaning simultaneously when immersed in a proper solvent,
such as toluene. Furthermore, because of the direct immersion there
are no problems with index of refraction corrections associated
with cells which do not maintain cylindrical symmetry about an axis
perpendicular to the scattering plane. Hence, well-known,
non-proprietary standard calibration procedures can be used for
each detector.
[0035] The versatile scattering chamber is very inexpensive to
fabricate and, in some instances, can be even treated as
disposable. This contrasts to the generally high cost of the
scattering cell/detector assembly in prior art units.
[0036] Unlike existing SLS units, the use of fiber optic detectors
and narrow beam focusing make the system quite insensitive to
alignment. This has the significant advantage of allowing the unit
to operate with a simple coarse alignment, whereas a high degree of
alignment is normally required in existing systems. This is
achieved because the acceptance cone of the fibers is fairly large
(typically 9.degree.) and the beam is collimated to usually less
than 100 microns. Hence, at a remove of 3 mm from the fiber, the
beam can be moved up and down approximately 0.5 mm for a 9.degree.
acceptance angle fiber, without significantly changing the amount
of scattered light entering the fiber.
[0037] Properly minimizing the scattering volume with a focused
beam and using fiber optic detectors and fast detection electronics
allow unfiltered samples to be measured, even when no flow or other
relative motion between sample and detector exists. This is a major
advance, considering that SLS in conventional instruments only
became reliable after chemical filtration technologies improved
considerably.
[0038] The present invention includes a submersible device, which
measures relative light scattered at various angles from a large
number of scattering particles, from which absolute macromolecular
and colloidal characterization is made, via well known,
non-proprietary calibration procedures and the well known
procedures of Zimm and others. The device need not contain an
optically transparent cell interposed between the scattering medium
and the incident optic delivering the incident beam and the optical
fibers used for detection.
[0039] The submersible absolute macromolecular characterization
device described in the previous paragraph preferably consists of a
completely solid or perforated, or striated or otherwise partially
open solid piece, a ring member or a cylinder with a channel inside
into which sample liquid enters upon immersion. In this device,
polarized or unpolarized incident light (provided by a laser or any
other source of visible or ultraviolet light) is led into the
channel and spatially filtered with any suitable optical elements
such as a tubular lens, miniature convex lens, flat window, fiber
optic, irises, etc., or any suitable combination. The light so led
in can undergo any necessary degree of collimation, including none,
in order to make as narrow an incident beam waist in the detected
scattering volume as desired. Scattered light detection is
preferably achieved by fiber optic strands, or other fiber optic
light conduits, which are exposed to scattered light in the
channel, either by virtue of being recessed into the walls of the
channel, being flush with the walls of the channel, or protruding
into the channel. The degree of collimation of incident light and
the diameter of the detecting fibers are combined to optimize the
detected scattering volume for the particular sample to be
measured. The transmitted incident light is preferably `dumped`
using any standard beam dump arrangement, such as a hole, Rayleigh
horn, prism, etc. The channel is preferably black or blackened to
reduce glare and stray light from the incident beam. The delivery
and detection optical train elements are preferably gathered into a
harness leading to the photodetectors, amplifiers and computer
external to the light scattering probe.
[0040] Instead of the probe mentioned above which can be immersed
in sampling liquid, a different probe can be provided, into whose
channel, plugged at one end, rather, a small quantity of sample
liquid can be transferred (e.g. by pipette, or by scooping) and
therein reside while the scattering measurements are made.
[0041] Likewise, a third probe having suitable liquid flow
connectors need not be immersed in sampling liquid; instead,
through its channel the sample liquid can be made to flow for
scattering measurements.
[0042] The submersible absolute macromolecular characterization
device described above can consist of a ring member, not
necessarily closed or circular (e.g. rectangular, elliptical,
horseshoe, or any other shape capable of holding the light source
fixed relative to the detection fibers (or photodetector when
detection fibers are not used)) containing the incident beam
delivery optics, beam dump and detection fibers, and which can be
immersed directly in a sample liquid for scattering measurements.
Alternatively, the submersible absolute macromolecular
characterization device described above can consist of a ring
member, not necessarily closed or circular (e.g. rectangular,
elliptical, horseshoe, etc.) which can be placed inside of a
chamber in a cell of appropriate dimension, so as to protect it
from the liquid it is immersed in, ambient light or other factors,
or to otherwise control how sample liquid reaches the ring member
for scattering measurements.
[0043] The present invention includes a method whereby any of the
devices described above, with appropriately small scattering
volume, can be used to measure sample solutions which may contain
significant numbers of large scattering contaminants by using fast
enough photodetector response to identify, count and eliminate
scattering intensity spikes produced by the contaminants, thereby
enabling the recovery of the uniform scattering background due to
the population of polymers or colloids in the sample. The sample
may be either stationary or flowing to accomplish this. Very
roughly, the number density of contaminant particles can be on the
order of one per scattering volume, so that very tiny scattering
volumes allow for relatively higher concentrations of impurity to
be present. The identified spikes can be counted and used to assess
the particle density of large particles in a solution, and how this
number may change in time, as well as simultaneously determining
the absolute uniform scattering from a population of polymer or
colloids.
[0044] The present invention also includes a method whereby the
flow mode of the present invention described herein can be used to
measure, in real-time, the increase of the weight average molecular
weight of polymers being produced in a solution of chemicals
undergoing polymerization reactions. This method preferably
includes the on-line dilution of the polymer containing solution to
bring it into a concentration range where useful, absolute
scattering can be measured. This range is where the quantity
2A.sub.2cM.sub.w is preferably smaller than 1, but can actually be
as much as 10. Such dilution can be achieved by the use of
hydraulically pulling polymer solution and pure solvent through an
hydraulic `T` or other mixing chamber via a pump or other
flow-causing device. A concentration sensitive detector is
preferably installed in the line of fluid flow so as to determine
in real-time the actual concentration of polymer in the diluted
solution. Such a detector may be a refractive index monitor,
ultraviolet or visible spectrophotometer, etc.
[0045] The present invention also includes a method whereby any of
the devices herein described are used to monitor the changes in
time of polymer solutions which are undergoing degradation,
polymerization, aggregation, gelling, or phase separation.
[0046] The present invention also includes a method whereby any of
the devices herein described are used to usefully characterize
heterogeneous solutions, containing populations of both polymers or
colloids and large particulate scatterers, whether either or both
of these changes in time or not.
[0047] The present invention comprises a kit including light
scattering devices of the type described herein, whereby a wide
variety of optical probes (with widely varying dimensions, sample
capacities, fiber optic types, numbers of angles) made of different
materials to withstand different environments can be connected to
the same `back-end` of detection electronics, signal processing and
data analysis. The kit can also include the detection electronics,
signal processing and data analysis.
[0048] The present invention also includes a submersible light
scattering probe for the absolute characterization of polymer and
colloid solutions which includes a ring member made of a preferably
dark, opaque material, having embedded therein a plurality of
optical fibers which can be connected to optical detectors remote
from the probe. The ends of the optical fibers are preferably in
direct contact with the fluid being tested. Instead of submersing
the probe in a fluid, fluid can be caused to flow through the
probe, placed in the probe, or placed in a transparent vessel
placed in the probe. Individual large scattering particles can also
be detected, counted, and characterized at the same time absolute
characterization of the polymer or colloid solution is
performed.
[0049] This method preferably includes the on-line dilution of the
polymer-containing solution to bring it into a concentration range
where, useful, absolute scattering can be measured. This range is
where the quantity 2A2cMw is preferably smaller than 1, but can
actually be as much as around 10 (or even higher). Such dilution
can be achieved by the use of hydraulically pulling polymer
solution and pure solvent through an hydraulic `T` or other mixing
chamber via a pump or other flow-causing device. A concentration
sensitive detector is preferably installed in the line of fluid
flow so as to determine in real-time the actual concentration of
polymer in the diluted solution. Such a detector may be a
refractive index monitor, ultraviolet or visible spectrophotometer,
etc.
[0050] FIG. 16 illustrates the scheme used by the inventor et al.
(ref. 6) for the online monitoring of a poly(vinyl pyrrolidone), or
PVP, reaction.
[0051] The present invention also includes a method whereby
heterogeneous solutions, containing populations of both polymers or
colloids and large particulate scatterers, can be characterized,
whether either or both of these changes in time or not.
[0052] FIG. 17 shows a three vessel scheme, wherein one vessel
contains the polymer or colloid to be characterized, and two other
vessels are used, each of which contains different solvents. For
example, the polymer might be electrically charged (i.e. a
polyelectrolyte) and be dissolved in pure water in the first
vessel, whereas solvent #1 might be pure water, and solvent #2 an
aqueous solution containing salt. With such an arrangement it would
be possible to maintain a fixed polymer concentration by pulling a
fixed fraction from the first vessel, while the total salt
concentration that the polyelectrolyte is subjected to is
continuously changed from pure to very salty water (e.g. 4 molar
NaCl). Since the concentration of polyelectrolyte is fixed, and
known, a LS detector alone would furnish online information on how
the polyelectrolyte conformations and interactions are changing as
the solvent becomes more salty. Adding a viscometer would further
indicate how the polyelectrolyte hydrodynamic properties are
changing with salt concentration.
[0053] Similarly, other types of polymers and/or colloids could be
in the first vessel, and solvent #1 could be of one type (e.g. pure
water) and solvent #2 could be of another type (e.g. an alcohol or
other solvent miscible in water). In this way the effects of
changing solvent composition on the polymer and/or colloid could be
continuously assessed online. Many other variations are possible,
since the second solvent could also contain a polymer and/or
colloid which interacts with the first polymer and/or colloid
solution. The three vessel arrangement hence allows complete phase
diagrams to be obtained online. Another area of use would be to
determine under what solvent conditions globular polymers, such as
proteins, become denatured into random coils.
[0054] Extension to more than three vessels is straightforward and
is contemplated by the inventor.
[0055] The device of one embodiment of the present invention
consists of a pump capable of continuously pumping fluids of
arbitrarily high viscosities at a fixed or programmably changing
dilution factor, even when the viscosity of the fluid varies
immensely (e.g. six orders of magnitude) over time. Such a pump
will normally be of the gear, lobe, screw or peristaltic type. This
primary pump may optionally use a recirculation of the vessel
fluid, to insure fresh sampling at every moment, in which a
fraction of this recirculating flow is either continuously, or at
intervals, mixed with a larger volume of solvent, which is pumped
by a separate pump, for which less stringent specifications are
required, since it always pumps a low viscosity fluid. The fluids
emanating from the primary and solvent pumps are mixed via a mixing
chamber which can take any number of forms; e.g. a microbore `T`
type mixer, an actively stirred micro-chamber, a passive mixer, or
combination of the above. Either during or directly after mixing
the liquid passes through a vented chamber at atmospheric pressure
so that bubbles of gas will be exhaled and not introduced into the
detector feed. After mixing, debubbling, and any other conditioning
stages (e.g. heating to evaporate monomer), the mixed liquid is
pumped by a final pump through the detector train, whose output
optionally incorporates another dilution stage, either at high or
low pressure, before pumping to the detector train. The detector
train itself contains means of determining the concentration, if
necessary, of the polymeric or colloidal solute, such that it is
not imperative that the dilution be performed to high accuracy.
[0056] Because all the pumps used are potentially controllable by a
programmable logic controller, personal computer, palm pilot, or
other electronic device containing a microprocessor the ability to
control both the dilution factor and various flow rates is
straightforward.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0057] For a further understanding of the nature, objects, and
advantages of the present invention, reference should be had to the
following detailed description, read in conjunction with the
following drawings, wherein like reference numerals denote like
elements and wherein:
[0058] FIG. 1 is a perspective view of the preferred embodiment of
the apparatus of the present invention;
[0059] FIG. 2 is a side view of the preferred embodiment of the
apparatus of the present invention immersed in a sample liquid;
[0060] FIG. 3 is a side view of the preferred embodiment of the
apparatus of the present invention being used in a flow mode;
[0061] FIG. 4 is a perspective view of the preferred embodiment of
the apparatus of the present invention being used in a fill
mode;
[0062] FIG. 5 is a perspective view of the preferred embodiment of
the apparatus of the present invention being used in an insert
mode; and
[0063] FIG. 6 is a perspective view of an alternative embodiment of
the apparatus of the present invention;
[0064] FIG. 7 is a schematic of how a diode laser might be
incorporated into a base plate in a ring member version of the
present invention;
[0065] FIG. 8 is a schematic representation of a `pinhole mode` of
detection;
[0066] FIG. 9 is a schematic representation of an `acceptance angle
mode` of detection;
[0067] FIG. 10 shows a fill mode Zimm plot for high molecular
weight PVP irradiated with a 10 mW Argon ion laser and each angle
calibrated to pure toluene;
[0068] FIG. 11 shows an immersion mode Zimm plot for unfiltered
solutions of high molecular weight PVP ("1.3MD" PVP) irradiated
with a 10 mW Argon ion laser, using 150 micron optic fiber in 3
inch diameter vessels of solution;
[0069] FIG. 12 shows a flow mode Debye plot for high molecular
weight PVP at .theta.=90.degree. irradiated with a 488 nm Argon ion
laser, compared to the results of a Wyatt Dawn-F at 144.degree.
(633 nm He--Ne laser), with error bars;
[0070] FIG. 13 shows a flow mode measurement of a 0.5 mg/ml high
molecular weight PVP (1.3MD PVP) solution with "contamination" by
10 micron latex spheres, using a 300 micron optic fiber at
90.degree. and a 5 mW diode laser;
[0071] FIG. 14 shows a flow mode measurement of a polymerization
reaction;
[0072] FIG. 15 shows the relative intensity converted to apparent
mass (Kc/I) using equations (1)-(3), plotting approximate apparent
mass versus real-time for PVP polymerization using a flow mode,
using a 300 micron optic fiber at 90.degree. and a 5 mW diode
laser, and starting with 300 mg/ml VP diluted to about 6 mg/ml
on-line;
[0073] FIG. 16 illustrates the scheme used by the inventor et al.
(ref. 6) for the online monitoring of a poly(vinyl pyrrolidone), or
PVP, reaction;
[0074] FIG. 17 shows a three vessel scheme, wherein one vessel
contains the polymer or colloid to be characterized, and two other
vessels are used, each of which contains different solvents;
[0075] FIG. 18 shows typical online, electroviscous data for
hyaluronic acid.
[0076] FIG. 19 shows a typical embodiment of the apparatus of the
present invention; a two stage, recirculating mixer.
[0077] FIG. 20 shows data from a styrene polymerization reaction,
using a Greylor peristaltic pump.
[0078] FIG. 21 shows data from a styrene polymerization reaction,
using a custom-built Zenith Corporation gear pump.
[0079] FIG. 22 shows raw data for the reaction from the detector
train.
[0080] FIG. 23 shows the fraction of monomer converted as a
function of time.
[0081] FIG. 24 shows the reduced viscosity of the polymer, and the
weight averaged polymer mass M.sub.w.
DETAILED DESCRIPTION OF THE INVENTION
[0082] The preferred embodiment of the present invention is a
submersible light probe 20 (see FIG. 1) including a ring member 21
made of a preferably dark, opaque material, having embedded therein
a plurality of optical fibers 41 which can be connected to optical
detectors 118 (see FIG. 7) remote from the probe 20. The ends 44 of
the optical fibers 41 are preferably in direct contact with the
fluid 51 (see FIG. 2) being tested. In a first variation of the
invention (see FIG. 3), fluid is caused to flow through the probe
20. In a second variation (see FIG. 4), a base plate 81 is added so
that the ring member 21 can contain a fluid to be tested. In a
third variation of testing (see FIG. 5), a clear container
containing fluid to be tested is placed through the ring member 21.
In yet another variation of the invention (preferably only when the
probe is not submersible), photodetectors can replace the optical
fibers.
[0083] The purpose of the probe is to measure light scattering by
particles in a fluid (static light scattering (SLS)).
[0084] It is believed that this is the first probe for SLS or TDSLS
where light detectors (the optical fibers) are actually in the
fluid, as opposed to being separated from the fluid by glass or
some other media.
[0085] FIG. 1 is a perspective view of the minimal ring member
version 20 of the present invention. FIG. 1 shows the essential
layout of the ring member-version optical assembly 20, with fiber
optic detectors 41, beam dump 32, and a laser beam 31 entering a
chamber 22 through a window 23, either through local mounting and
lensing, or via fiber optic transfer through one of the harness
fibers. The ring member channel 22 may alternatively have a square
or polygonal cross-section, instead of circular, which may be
particularly useful for single or few angle detection. Such single
or few angle detection may warrant simply mounting photodiodes on
the side of the chamber, rather than using fiber optics. The ring
member o.d. and i.d. can vary widely, depending on the application
(specific dimensions for test versions are given in the
"Experimental Verifications of the Invention", below). The range of
i.d. can be, for example, from about 2 mm to 50 cm, with the o.d.
being determined by desired wall thickness, which can, for example,
range from about 1 mm to 10 cm. The length of the ring member can
also, for example, vary from about 3 mm to 10 cm. Optionally a cowl
114 (see FIG. 7) made of rigid or flexible dark material can be
placed over the ring member in any of its modes of operation to
shield against ambient light.
[0086] FIG. 2 shows the immersion mode of the present invention.
The ring member assembly 20 is attached to a handle 61. The hollow
handle 61 contains an optical harness 43, which has been formed by
drawing all the optical fibers 41 together. A sheath 45 on the
outside of the ring assembly 20 protects the fibers 41 that are led
into the harness 43. A diode laser 62 can be mounted directly on or
to the handle 61 for an integral optical assembly/light source
version, or the beam can be led in through a fiber optic in the
harness 43.
[0087] FIG. 3 shows the flow mode of the present invention. Ring
member assembly 20 is sandwiched between two end-pieces 71, each of
which has a hydrodynamically shaped flow channel 72, and standard
HPLC tubing and fittings 73 for liquid to be injected through the
ring member assembly 20 via syringe, pump, etc. There are
preferably O-rings 74 between the ring member 20 and the end-pieces
71, and the three pieces are held together by through-bolts 75, or
a bracket.
[0088] FIG. 4 shows the fill mode of the present invention. Ring
member assembly 20 can have a base plate 81 attached, so that
sample solutions can be pipetted, scooped, or otherwise introduced
into the channel, as with dropper 85. A simple modification of ring
member assembly 20 could involve not boring the channel 22 all the
way through the ring member assembly 20 instead of using a
removable base plate 81.
[0089] FIG. 5 shows the insert mode of the present invention. A
cylindrical vial or cell 92 containing sample solution 91 is simply
inserted into ring member assembly 20. This can be advantageous
where the sample 91 may be damaging to the ring member assembly 20,
or where multiple samples are prepared and stored in vials and are
to be measured individually on multiple occasions.
[0090] FIG. 6 shows the integral chamber version 100 of the probe
of the present invention. By lengthening the ring member version, a
one piece unit 100 can serve for both the flow chamber, to which
HPLC connections are directly made, and for fill and immersion
modes. Chamber o.d. and i.d. follow the ranges mentioned above,
whereas the length for any given chamber can considerably exceed
the ring member lengths; e.g., lengths can be from about 1 cm to 30
cm. Channel bore 102 can optionally be tapered. In FIG. 6, the
laser input 31 can either be through lensing or via fiber.
[0091] FIG. 7 is a schematic of how a diode laser 62 might be
incorporated on or into a base plate 161 in the ring member version
20 (applicable also to the chamber version 100). Also shown is an
optional cowl or hood 114 to cover the ring member assembly 20 to
reduce any effects of ambient light. Also shown is the overall
schematic of the optical assembly attached via optical harness 43
to the photodiode/electronic assembly 111, which then transmits
scattering signals to a microcomputer 112. If a remote laser is
used, instead of on the base plate 161, then the laser would
normally be housed with the photodetectors 118, and the beam led
into the ring member assembly 20 or chamber 100 via a fiber in the
optical harness 43. In FIG. 7, a converging lens 63 is used to
focus the laser beam.
[0092] FIGS. 8 and 9 are schematic representation of detection
modes. The `pinhole mode` (FIG. 8) occurs when the fiber 41 is not
completely inserted into the through-hole 42 in the chamber wall,
and the angle defined by the end 44 of the fiber 41 and the end of
the hole is less than the acceptance angle of the fiber 41 in the
particular solvent in which it is immersed. The "acceptance angle
mode" (FIG. 9) is when said angle is larger than the acceptance
angle of the fiber, which means the acceptance angle of the fiber
itself will define the scattering volume 121.
[0093] FIG. 10 shows a fill mode Zimm plot for high molecular
weight PVP.
[0094] FIG. 11 shows an immersion mode Zimm plot for high molecular
weight PVP.
[0095] FIG. 12 shows a flow mode Debye plot for PVP at
.theta.=90.degree..
[0096] FIG. 13 shows a flow mode measurement of a 0.5 mg/ml high
molecular weight PVP solution with `contamination` by 10 micron
latex spheres. The spheres were in a concentration of 40,000
particles/cc. It is possible both to count the number of spheres
passing through the scattering volume, and obtain the absolute
scattering due to the PVP, when using the program REEDFLO (see
Appendix A of parent patent application Ser. No. 08/969,386) on
DT2801a. Thus, the present invention can simultaneously conduct
absolute macromolecular characterization of one substance and
individual particle counting and characterizing techniques on
another substance in the same fluid.
[0097] FIG. 14 shows a flow mode measurement of a polymerization
reaction. Vinyl pyrrolidone monomer at 300 mg/ml at T=80.degree. C.
is polymerized using hydrogen peroxide initiator. The polymerizing
mixture is withdrawn by a mixing pump, which dilutes the PVP to
about 6 mg/ml. The diluted mixture is then pumped through the flow
cell where the scattering is monitored continuously. Optionally, a
concentration detector, such as an index of refraction detector, or
ultraviolet or visible spectrophotometer, can be placed in the line
of sample flow.
[0098] FIG. 15 shows the relative intensity converted to apparent
mass (Kc/I) using equations (1)-(3).
[0099] The preferred embodiment of the present invention consists
of an optical assembly 20, from which a harness 43 of fiber optic
cables 41 leads out detected scattered light to a remote
photodetector and signal processing unit 111, 112, and optionally
brings in incident light. The signal processing unit 111, 112 is
itself composed of standard components such as photodiodes 118,
photomultiplier tubes, amplifiers, discriminators, microcomputer
112, etc.
[0100] The optical assembly 20 preferably consists of a solid
material. The minimal version consists of a ring member 21 around
which the fiber optic detectors 41, incident beam input optics 31,
and beam dump 32 are arrayed (see FIG. 1 for this embodiment). The
optical fibers 41 are either cemented into holes 42 in the ring
member 21, or are affixed with tiny optical fiber chucks (not
shown), and are gathered into a ruggedized harness 43, which is led
to the photodetector assembly 111, 112. The optical assembly 20 can
be connected to a handle 61, which may contain a laser 62, and can
be immersed directly in a sample solution 91 (see FIG. 2). The ring
member 21 can also be mounted on a base plate 161. The ring member
21 can also serve as a center portion for a segmented chamber, to
the endpieces 71 of which are connected hydraulic fittings 73 for
fluid to be pumped in and out through in the flow mode (FIG. 3). A
small baseplate 81 can be attached to the ring member assembly 20
for fill mode use (FIG. 4), or the bore 22 in the ring member
assembly 20 simply need not be perforated all the way through. For
insert mode, a sample vial 92 can be inserted directly into the
ring member assembly 20 (FIG. 5). In cases where ambient light
might give detectable interference, the ring 20 can be covered with
a simple cowl or hood 114 in both immersion, fill and insert modes.
In the tests presented below, ambient light was not a problem, and
no cowl or covering was used.
[0101] An integral chamber version 100 (see FIG. 6) can also be
made, and consists of a hollow channel or wall 101, normally
cylindrical, but which may also have elliptical, square or
polygonal cross section. The chief difference between the minimal
ring version 20 and integral chamber version 100 is that the
chamber 102 is simply longer than the ring chamber 22, so that
hydraulic fittings 73 can be directly connected. Furthermore, the
extra length provides additional shielding from ambient light, and
no cowl or other covering should generally be needed.
[0102] In either the ring version 20 or chamber version 100, the
internal diameter can be made over a wide range, depending on the
application. Typically this diameter will run from about 1 mm to 20
cm. The total channel volume may range, for example, from about 3
to 50,000 microliters, with a preferred range of 10 to 1000
microliters. The wider the channel diameter the less problem there
will be with stray light, but more sample solution will be
required. In industrial settings, for example, where large volumes
of sample are produced, and/or the samples are viscous, high volume
cells may be a convenient solution, and pose the most robust and
reliable means of achieving low stray light and highest ease of
alignment. In situations where sample volume is scarce, e.g. in
biotechnology research where only milligrams or less of substance
is available, the channel will be made much narrower. Because the
optical detection fibers 41 can plug into the same remote array 111
of photodetectors 118, the only change in fabrication in meeting
the demands of the high sample volume vs. the low volume user is in
the low cost optical probe assembly 20, 100. All photodetection,
electronics, computer interfacing and basic software 111, 112 can
remain the same.
[0103] In the walls of either the ring member or chamber versions,
are seated an optical window 23, lens, fiber, or other component
for delivering the incident beam into the channel, as well as
optical fibers 41 for detection of scattered light placed at any
number of scattering angles, usually from about 10.degree. in the
forward direction to about 170.degree. in the backscattering
direction. A detection fiber can also be placed at the site of the
beam dump (0.degree.). The fibers 41 can be cemented into holes 42
in the chamber 22, 102, or held in with tiny optical fiber chucks.
Hence, the delivery element for the incident light and the optical
fibers are in direct contact with the sample solution, or may be
coated with a suitable transparent material, including glass, for
protection against deleterious sample solutions. In the case for
example where only a single or few angles are desired, small
photodetectors (such as photodiodes) can be affixed directly to the
outside wall of the chamber, thus eliminating the optical fibers
41.
[0104] The body of the optical assembly in either ring member or
chamber versions can be constructed of any material suitable to
withstand the nature of the sample solution, such as stainless
steel, black anodized aluminum, ceramic, Teflon, nylon,
polycarbonate, or other plastics. The material is preferably
opaque, preferably black or blackened, to minimize glare and stray
light.
[0105] The power of the incident light is arbitrary, but will
typically range from 0.1 to 100 mW. For good detectability and
economy, the power range will preferably be from 0.25 to 50 mW. The
wavelength can likewise fall anywhere in the visible or ultraviolet
range. Since there are no requirements for coherence (unless a
single mode optical fiber is installed optionally to collect light
for dynamic light scattering, in which case a laser light source
would be required), nor does the incident light have to be
extremely monochromatic (a bandwidth of 50 nm would not be
excessive), the light source does not have to be a laser. As such,
conventional white light, broad band, or discrete line sources,
such as arc lamps, light emitting diodes, vapor lamps and
incandescent sources are all possible candidates for the incident
light. By the same token, if a multiple wavelength source is used,
it is possible to vary the scattering vector q 1 ( q = 4 n sin ( 0
/ 2 ) )
[0106] by introducing different discrete wavelengths and detecting
at a single angle; e.g. by selecting wavelengths with a
monochromator in front of a white light source and introducing
these into the input optics. Using light from around 200 to 800 nm
could yield a factor of four variation in q. This could avoid use
of multiangle detection, and require only a single fiber optic for
detection and single photodetector/amplifier. On the other hand, if
both multi-angle detection and multiple wavelengths are used then,
say, for wavelengths from 200 to 800 nm, and scattering angles from
15.degree. to 170.degree., the factor of q can be varied by as much
as a factor of 30. Appropriate collimation and/or focusing optics
are usually needed to introduce the source beam into the
channel.
[0107] In many applications use of a laser may be preferred. A
laser source would preferably be around 200-1000 nm, and more
preferably 450 to 780 nm, where the majority of economical, low
power, commercial lasers operate. The laser beam is preferably
focused at or near the center of the hollow channel, although an
uncollimated, or reduced and re-collimated beam will also work. The
beam waist can range from the diffraction limit of Gaussian beams
(.lambda.f/D, where .lambda. is the incident wavelength, D the
unfocused laser beam waist diameter and f the lens focal length)
typically on the order of 1 to 200 microns, up to a 2 mm unfocused
beam. The preferred beam waist diameter will depend on the intended
application, and would be given as an option to a potential user of
the invention, according to their needs. For example, measurement
of dilute solutions of small, clean solutions would tend to use a
wider beam waist, whereas concentrated solutions containing
significant stray scatterers would preferably use a very highly
collimated beam. Use of a highly focused beam and detectors
defining a small scattering volume allows less probability of
finding large particles in the scattering volume at any instant.
When a large particle enters, either with the sample stationary or
under flow, a large spike is produced which can then be recognized
and discriminated against, in order to recover the absolute
scattering from the desired scatterers. Sufficiently fast detector
response allows spikes to be identified, counted (for purposes of
large particle counting), and eliminated, to recover the desired
background scattering.
[0108] The method of delivering the beam can be directly through an
optical window on the chamber, via a tubular transfer lens, such as
the endo-index type, or via an optical fiber, either flexible or
rigid, with such lenses, pinholes and other light handling
components as is necessary to deliver the beam in focused or
collimated fashion, with the desired beam waist, and with a minimum
of glare and stray light. If the beam is delivered by optical
fiber, the laser can be remote from the optical assembly.
Alternatively, the laser can be mounted directly to the optical
assembly (FIG. 7).
[0109] Directly across from the incident beam is a beam dump 32 for
the incident beam 31 to minimize `glare` and stray light. This beam
dump 32 may be of any standard type, ranging from a hole, to a
`Rayleigh horn`, to a complete sub-system involving coated or
un-coated lenses, and/or prisms, mirrors, a photodetector, or other
optical components.
[0110] The optical fibers 41 may be of the multimode variety, whose
inside diameter may range from 10 to 1000 microns, the smaller
sizes being preferred where highly scattering samples are being
measured, or for subsequent use with dynamic light scattering. In
fact, a single, relatively large fiber diameter may be selected,
such as 500 microns, and a rotatable, annular mask can be affixed
to the channel wall, which would have varying diameter pinholes for
defining the field of view of each optical fiber. Alternatively,
the cell interior may be permanently outfitted with sets of
different diameter fibers, spaced closely about each selected
scattering angle, all of which could be continuously monitored. The
fibers themselves can be of virtually any commercial or research
grade. They must be chosen, however, so as to be compatible with
the solvent and sample conditions where the invention will be
applied. Where toluene is used, for example, the fibers must
withstand that solvent, so glass core fibers with glass cladding
and buffer would be preferred, or some similar substitute, such as
glass core with CPE (chloropolysulfatal ethylene) jacket from
Belden corporation.
[0111] The way the optical fibers 41 are attached to the cell 21,
101 helps to define the scattering volume. If the fibers reach
through the cell to the surface of the channel (chamber) 22, 102,
then the scattering angle will be defined by both the acceptance
angle of the fiber in the particular solvent the cell contains, and
the beam waist. Definition of the scattering volume in this way can
be termed the `fiber acceptance angle mode`. If the fiber 41 is
recessed back into a hole 42 in the chamber to the point where the
angle subtended by the two ends of the cylindrical hole 42 is less
than the acceptance angle of the fiber 41, then detection can be
said to be in the `pinhole mode`. The difference in detection modes
is shown schematically in FIGS. 8 and 9.
[0112] The optical harness 43 leads all the detection fibers to a
remote bank 111 of photodetectors 118. The fibers 41 can be coupled
to their respective detectors 118 by inserting them into
permanently aligned quick connect optical fiber connectors, as are
commercially available (e.g. Newark Corp. or Amphenol Corp.),
positioned in front of the detector surfaces.
[0113] The optical assembly can be used in several modes. In one of
its submersible modes, the assembly 20, with no additional
modifications, can be directly submerged into a sample solution 91
contained in a test tube 92, industrial tank, etc. As a remote,
fill mode unit, the channel may be capped at one end (or the
channel simply does not have to be bored completely through), which
allows a small quantity of sample to be pipetted, scooped, or
otherwise introduced into it and reside in it, remotely from the
main sample supply, if desired. Each end of the channel may also be
outfitted with a coupling to accept a fluid flow, so that the
assembly may also be used in flow mode, such as for monitoring,
optionally with on-line dilution, unfractionated polymers degraded
or produced in a vat, fractionated polymers from Size Exclusion
Chromatography, capillary hydrodynamic fractionation, etc. In this
mode of operation it may be desirable to hydrodynamically taper the
interior to optimize the flow past the plane of the optical fibers
and incident beam. The invention can also be used in insert mode,
whereby samples in sealed cells or vials can simply be inserted
into the ring member or chamber, in the traditional fashion. In
this case, one returns to the common situation in which there is a
transparent cell between the sample, incident beam and detection
optics.
[0114] The invention can be simultaneously cleaned and absolutely
calibrated by use of an appropriate solvent such as toluene, whose
absolute Rayleigh scattering ratio is known. The probe is immersed
in the solvent, or the solvent made to flow through it for cleaning
purposes. At the same time, the solvent scattering is monitored,
and when it reaches a steady value, this is used for determination
of the absolute calibration factors for each detection fiber.
[0115] As regards the minimal ring member version, it can be used
submersibly on its own or become a central portion of a three piece
unit. This may be desirable for purposes where quick interchange of
optical assemblies to different specifications, cleaner or newer
units are made, etc.
[0116] In both the ring member version 20 and integral chamber
version 100, an outer protective sheathing 45, such as a ring
member of plastic or metal may slip over the fiber optics 41
protruding externally from the ring member 21 or chamber wall 101.
Likewise, in all cases, the entire optical assembly, whether a ring
member or chamber, can be placed within a completely enclosed
housing, into which sample can be introduced either by flow or
immersion. Such a housing may be desirable when the optical
assembly needs special protection from a harsh (e.g. high
temperature) environment, or is immersed in turbulent or otherwise
potentially damaging or signal distorting liquids.
[0117] The present invention includes the aforementioned ring
member or integral chamber SLS probe. The incident beam 31 is
introduced into the device via optical window 23, or a fiber optic
and/or tubular lens and other optical elements, and scattered light
is taken out via fiber optics 41 whose tips 44 are arrayed at
various angles in the horizontal plane of the ring member 21 or
chamber wall 101. All the optical fibers 41 and elements are drawn
together into an `optical harness` 43, which is led to the `outside
world` through a hollow handle 61 on the device 20. The optical
fibers 41 carrying scattered light and issuing from the harness 43
are coupled to conventional optical detectors 118 (e.g. PIN or
avalanche photodiodes, photomultiplier tubes, etc.), whose voltage
or current signals are led to a conventional signal processing
device and/or into a computer 112. The optical probe portion
consists essentially of a piece of material, preferably dark, with
optical fibers and a few other inexpensive optical elements (such
as borosilicate windows 23) attached into a harness. As such, the
probe itself should be quite inexpensive and could even be
disposable. The photodetectors 118, signal processing and computer
analysis portions of the instrument are remote and permanent
(although quite portable), and represent the major cost. In some
cases, especially where few angles are involved, and submersible
operation is not a priority, photodetectors (e.g. photodiodes) can
be mounted directly to the chamber, thus avoiding use of the fiber
optic detectors.
[0118] In the submersible mode, calibration (and cleaning) can be
done by merely immersing the probe in a calibration solvent, kept
handy in a closed vessel. This could be toluene, or any other
solution whose absolute Rayleigh scattering ratio is known.
[0119] The software in Appendix A of parent patent application Ser.
No. 08/969,386 can serve as a basis for data reduction, analysis
and display. Data can be collected and reduced either on a standard
microcomputer, or by building a customized microprocessor based
unit. The software can include programmed criteria for averaging
scattering signals, identifying, counting and rejecting scattering
spikes from large, stray scatterers, and informing the operator
when signal collection is done. Software can access on-board
libraries to inform the operator of likely phenomena occurring in
the sample (e.g. aggregation, gelation, degradation), and problems
such as poor solution quality (e.g. too much `dust`), presence of
aggregates, or other anomalies.
Experimental Verifications of the Invention
[0120] I) Fill Mode Tests:
[0121] A) Transfer Lens Version/Single Angle
[0122] A first prototype of the invention in the integral chamber
version was made in order to assess whether absolute macromolecular
characterization, in terms of molecular mass, was feasible. This is
meant to be only a demonstration of the feasibility of the
invention, not a highly precise absolute molecular mass
determination nor critical comparison of the invention's
performance with a commercial instrument.
[0123] Dextran of nominal mass 200,000-300,000 g/mole was selected
for the measurement. It was mixed at 0.003 g/cm.sup.3 in an aqueous
solvent containing 0.1 Molar NH.sub.4NO.sub.3 and 0.1% sodium azide
for protection against bacterial contamination. There is nothing
special about this particular solvent, and even pure water would
have been adequate (since dextran is a neutral polymer and is not
subject to the unusual physical effects that charged polymers
display in pure water).
[0124] An optical unit was fabricated from a 17/8" inch long piece
of, e.g., black nylon round stock of 5/8" o.d. An inner,
cylindrical channel of diameter 7.7 mm was bored concentric with
the axis. The inner ends of the channel were tapped to accommodate
standard 3/8" plugs, barbs and other hydraulic fittings.
Perpendicular to the cylinder axis, a hole was drilled to
accommodate a 1.98 mm o.d. Endogrins.RTM. lens, obtained from
Edmund Scientific Co. Straight across from this hole on the
opposite side of the channel a larger diameter hole was drilled for
use as a beam dump. At 90.degree. to the incident light hole a
small hole was drilled to accommodate an optical fiber with inner
core 100 microns and cladding 140 micron o.d. The fiber was
inserted into the hole in the channel, and was found to work best
when protruding but slightly from the hole into the channel. Both
the fiber and lens were secured in their holes with optical putty.
The opposite end of the fiber, which was about two feet long, was
secured remotely from the optical assembly into a fiber optic chuck
from New Focus Co., and butted up against the photosensitive
surface of a Hammamatsu photodiode with integral FET op-amp,
contained inside a light-tight box, containing both the diode/FET
and an additional standard operational amplifier stage.
[0125] The amplified signal was fed into a Nicolet 4094B digitizing
oscilloscope, although any data collection device with a rate of 1
KHz or faster would have sufficed. Sampling at 1 KHz or faster
allows spikes from diffusing impurity particles and fluctuating
scattering levels to be recognized and rejected, leaving the
desired signal from the polymer or colloid scatterers. In fact,
spike and fluctuation rejection was used in this and other
tests.
[0126] Light of wavelength 488 nm and approximately 20 mW was from
a Coherent Corp. Argon ion laser, which had an output beam waist of
about 2 mm. The light could be delivered either highly focused or
uncollimated. For high focusing, a 5 mm lens with a focal length,
f=5 mm from Edmund Scientific was placed external to the optical
assembly, and led to a beam waist of about 1.5 microns. This was
transferred into the channel of the optical assembly via the 1.98
mm Endogrins.RTM. lens, which was 6 cm long. Alignment of the
delivered beam with respect to the detection fiber optic at
90.degree., and signal maximization for this arrangement was
achieved by using a solution consisting of a 1/40 dilution of 190
Angstrom latex spheres from Duke Scientific, although any
moderately scattering solution, such as water with a tiny drop of
milk or coffee creamer powder, would be adequate.
[0127] The system was then tested by measuring, sequentially, the
photodiode dark count (i.e. with no laser beam entering the optical
assembly), the photovoltage with pure water, with a 3 mg/ml
solution of dextran, and toluene. The various liquids were
introduced into and removed from the cell with a long, glass
pipette with a rubber suction bulb at one end. The photovoltages
are listed below:
1 Table of Photovoltages (accuracies are to about +/- 1 mV) app. M
volt. scattering Rayleigh ratio, app. M Wyatt Dawn measured (mV)
difference K I (cm.sup.-1) Kc/I (.theta. = 90.degree.) F (.theta. =
144.degree.)** Photodiode -65 NA NA NA NA NA NA dark voltage pure
water -57 NA NA NA NA NA NA 3 mg/ml -30 I.sub.dex - I.sub.water =
1.46 .times. 10.sup.-7 7.63 .times. 10.sup.-5 4.23 .times.
10.sup.-6 174,000 191,000 dextran 27 toluene -51 I.sub.tol -
I.sub.dark = NA 3.96 .times. 10.sup.-5* NA NA NA 14 dn/dc = 0.142
for dextran *This is the known Rayleigh ratio for toluene at T =
25.degree. C. for .lambda. = 488 nm. **This is the proper angle for
comparison, since the Dawn-F was used with a 632 nm He--Ne laser,
and the test chamber with a 488 nm Argon ion laser.
[0128] The Zimm equation for SLS, when
q.sup.2<S.sup.2><<1 is 2 Kc I = 1 M app = 1 M w ( 1 + q
2 < S 2 > z 3 ) + 2 A 2 c ( 1 )
[0129] where I is the excess Rayleigh scattering ratio from the
polymer solution (the total scattering minus the pure solvent
background). M.sub.app is the apparent mass, defined as per the
equation (i.e. it neglects the effects of finite 2A.sub.2c and
<S.sup.2>.sub.z effects). M.sub.w is the weight averaged
polymer mass, <S.sup.2>.sub.z is the z-averaged radius of
gyration, A.sub.2 is the second virial coefficient, c is the
polymer concentration in g/cm.sup.3, and K is given, for vertically
polarized light, 3 K = 4 2 n 2 ( n c ) 2 N A 4 ( 2 )
[0130] where n is the index of refraction of the sample solvent
(n=1.33 for water), and .lambda.=4.88.times.10.sup.-5 cm, is the
vacuum wavelength of the incident light.
[0131] The absolute scattering I was calculated according to 4 I (
q ) = V ( q ) - V s ( q ) V c ( q ) - V d ( q ) I c f ( 3 )
[0132] where V(q)is the photodetector voltage from the sample
scattering at wave vector q, V.sub.s(q) is the scattering voltage
at q of the pure solvent in which the polymer or colloid is
dissolved, V.sub.c(q) is the scattering voltage of the calibration
solvent scattering at q, and V.sub.d(q) is the dark voltage of the
photodetector at q. I.sub.c is the known, absolute Rayleigh
scattering ratio for the calibration solvent. For toluene at
25.degree. C., I.sub.c=1.406.times.10.sup.-5 cm.sup.-1 at 633 nm,
and 4.96.times.10.sup.-5 cm.sup.-1 at 488 nm. In equation 3, f is
an optical correction factor, given approximately as (n.sub.sample
solvent/n.sub.calibration solvent).sup.3. This accounts
approximately for the difference in field of view and detector
solid angle for optical fibers in the chamber.
[0133] For water n=1.333 and for toluene n=1.494 so that f is
approximately 0.71.
[0134] The results for the dextran are shown in the above table.
The apparent mass of 174,000 (at .theta.=90.degree.) is obtained
from the invention and 191,000 from the Wyatt Dawn F (at
.theta.=144.degree.). At these angles, q.sup.2 is approximately the
same for each instrument. At any rate, R.sub.g=225 Angstroms for
this Dextran (as measured on the Dawn F), so that there is very
little q.sup.2 dependence over the visible light range.
[0135] The fact that the apparent mass from the invention is within
10% of the value of that obtained from an established instrument
clearly demonstrates the feasibility of making absolute molecular
mass determinations. Refinement of the instrumentation should make
results even more accurate. At any rate, it is generally recognized
in the SLS field that molecular weights of polydisperse samples are
seldom accurate to more than a few percent.
[0136] B) Multiple Angles
[0137] A similar chamber (with no hydraulic fittings) was made
except that it was outfitted with detection fibers at 70.degree.,
90.degree. and 135.degree., and two opposed 3 mm sapphire windows,
glued into holes in the chamber, were used for beam ingress and
egress. Toluene was used for absolute calibration at each angle.
Zimm plot results from a solution of high molecular weight PVP are
shown in FIG. 10. Ten mW of argon ion laser power were used, and a
50 mm focal length lens was used to focus the laser beam through
the window in the chamber.
[0138] II. Immersion Mode Test:
[0139] An immersion cell was constructed from nylon roundstock of
16 mm outer diameter and 12 mm i.d. and 8 mm long. 150 micron
optical fibers were glued in with epoxy at 45.degree., 90.degree.
and 150.degree., with their front surfaces at the level of the
inner cell diameter face. Two 3 mm holes were cut in opposite ends
of the cylinder, and were left empty for the tests (i.e. neither
entrance window nor beam dump were used). The optical fibers
leading to the remote detector were secured so that no additional
bending or deformation of them occurred, since additional bending
or deforming leads to large losses in transmitted light. A tubular
stainless steel handle was attached to the cylinder to allow for
manipulation. The cylinder was immersed in 3" diameter beakers
containing the test liquids, and the handle, protruding from the
solution, was secured with a ringstand. 20 mW of Argon ion laser
power were delivered in a beam from above the beakers, and a 50 mm
focal length lens was used to focus the light in the center of the
cylindrical chamber.
[0140] Scattering tests at the three angles were carried out using
0.2, 1.0, 1.5 and 2.0 mg/ml solutions of a high molecular weight
polymer, PVP. A digitizing oscilloscope was again used to monitor
the detected light at each angle, one at a time. These solutions
were unfiltered. Identification and rejection of spikes from large
impurity particles diffusing through the scattering volume and
fluctuating signals from other causes allowed this unusual series
of measurements on unfiltered solutions to be made. The scattering
voltage of toluene at each angle was used to find the absolute
calibration factor at each angle. FIG. 11 shows typical results.
These compare quite favorably with the results for the fill mode
example above (I-B).
[0141] III. Flow Mode Tests
[0142] A 3-piece flow cell was constructed out of nylon roundstock
of 16 mm o.d The central portion was 8 mm long, with a 7 mm bore,
and contained a single 300 micron fiber epoxied in at a scattering
angle of 90.degree.. Two 3 mm sapphire windows were mounted on
opposite sides of the central bore, one for laser beam ingress, the
other for egress. Endcaps of the same material and o.d. pressed on
each side of the central portion and O-rings created a seal. Round
aluminum plates outfitted with long bolts served to clamp the
endcaps to the central piece. The endcaps each had a small hole
drilled in them for fluid to reach the bore of the central portion,
and each was outfitted with a standard GPC fitting, allowing
attachment of standard PEEK (polyethyleneethyleneketone) HPLC (high
performance liquid chromatography) tubing to allow liquid samples
to be pumped in and out.
[0143] The basic construction of the center portion can be
identical to that of the immersion cell, making the two ultimately
interchangeable, or at least slight modular variations of each
other. Also, these cells can easily become fill mode cells by
simply adding a base plate (as in the drawings).
[0144] A) Debye Plot at a Single Angle
[0145] Solutions of high molecular weight PVP of concentrations
0.25, 0.5, 1.5 and 2.0 mg/ml were pushed through the cell manually
with a syringe, at roughly 1 ml/min. The experiment was repeated
several times and error bars obtained. Kc/I at .theta.=90.degree.
is shown in FIG. 12, along with the associated error bars, and a
comparison with results from a Wyatt Dawn-F. Ten mW of argon ion
laser power were used, and a 50 mm focal length lens was used to
focus the laser beam through the window in the chamber.
[0146] B) Discrimination Against Large Particles
[0147] The present inventor wrote program REEDFLO (see Appendix A
of parent patent application Ser. No. 08/969,386) to capture data
through a DT2801-a analog-to-digital converter board and perform
averaging and data storage functions. Maximum speed is about 40
microseconds per point with this board, and up to eight separate
detectors can be monitored per board in the differential input
mode. The idea was first tested as to whether the flow cell with
small scattering volume could usefully measure both absolute
polymer scattering levels and identify and count spikes from large
particles. Ten mW of argon ion laser power were used, and a 50 mm
focal length lens was used to focus the laser beam through the
window in the chamber. The scattering volume was roughly
5.times.10.sup.-7 cc.
[0148] To this end a mixture of 0.5 mg/ml PVP of molar mass around
10.sup.6 grams/mole was mixed with Duke Scientific 10 micron latex
spheres such that the sphere concentration was 4.times.10.sup.4
particles per cc. This gave roughly an average of 0.02 particles
per scattering volume. The solution was pushed through the cell
manually using a syringe, roughly at a flow rate of 1 ml/minute.
The 5 mW diode laser (wavelength=635 nm) was used as the light
source.
[0149] FIG. 13 shows that the cell was capable of measuring both
the homogeneous background scattering from the polymers, and both
identify and count the number of large particles in the flowing
sample. Given the pure solvent level shown on the drawing, it is
hence possible to recover the absolute intensity scattered by the
homogeneous polymer background scattering. A significant degree of
contamination by large particles can hence be tolerated in this
system.
[0150] C) Kinetics of Polymerization
[0151] The kinetics of polymerization were carried out in real-time
using the flow cell. A 5 mW diode laser was used, and a 50 mm focal
length lens was used to focus the laser beam through the window in
the cell. A 30% solution of vinyl pyrrolidone (VP) monomer was
mixed in water with 0.1% ammonia, and the solution heated to
80.degree. C. The polymerization was initiated with 0.7% hydrogen
peroxide. At high concentrations, such as 30% VP, there is very
little change in light scattering intensity as polymerization
proceeds (i.e. in eq. (1) 2A.sub.2c is much larger than
1/M.sub.w(1+q.sup.2<S.sup.2>.sub.z/3)). (Hence the reaction)
solution must be diluted for TDSLS to be a useful monitor of
M.sub.w in real-time. To do this, concentrated reactant is
withdrawn with a pump and mixed with solvent from a separate
reservoir of pure solvent. This can be achieved by using a
hydraulic `T` one arm of which goes to the concentrated reaction
solution, and the other to the pure solvent, with the mixed output
being then pumped out by a pump and forced through the scattering
flow chamber. It turned out that use of a programmable mixer was
more convenient for mixing reactant and pure solvents. A standard
ISCO (corporation) 2350 HPLC pump was used to pull mixed material
from this pump and push it through the flow cell and refractive
index (RI) detector, which was placed in series with the flow to
measure the concentration, and any possible variations, of the
diluted sample. For this experiment the reaction mixture, initially
at 30% VP, was diluted so that the sample passing through the flow
chamber was at 6 mg/ml.
[0152] FIG. 14 shows the results of a polymerization reaction in
terms of scattered intensity in arbitrary units vs. time, whereas
FIG. 15 shows the approximate apparent mass, obtained by eqs.
(1)-(3). The apparent mass is simply I/Kc. For PVP of mass about 30
kD, there is no significant angular dependence, so
q.sup.2<S.sup.2>.about.0. Furthermore,
A.sub.2.about.5.times.10.sup.-4 so that at a PVP concentration of
0.006 g/cm.sup.3, 2A.sub.2cM.sub.w.about.0.18. Such a correction to
the apparent mass, about 18%, is easily taken into account.
[0153] Preferably, optical fibers 41 are attached to ring member 21
with fiber optic light chucks, such as those commercially available
from Upchurch Company.
[0154] FIG. 16 shows apparatus for an online measurement of
M.sub.w, monomer conversion, total solute concentration and reduced
viscosity during a polymerization reaction. The method and results
are described in detail in Florenzano, Strelitzki and Reed,
Macromolecules, vol. 31, pp. 7226-7238, 1998, "Absolute, On-line
Monitoring of Molar Mass during Polymerization Reactions". In
summary, vinyl pyrrolidone monomer at 200-300mg/ml at
T=60-80.degree. C. was polymerized using hydrogen peroxide
initiator. The polymerizing mixture is withdrawn by a mixing pump,
which dilutes the PVP to about 6 mg/ml. The diluted mixture is then
pumped through the light scattering, ultra-violet absorption,
viscosity and refractive index detectors, whence the mentioned
polymer properties are obtained online.
[0155] The reason the technique will not work for undiluted reactor
liquid is detailed in the cited reference. In brief, at high
concentrations of monomer and polymer, the total scattering from
the solution will usually be dominated by inter-polymer effects,
and will not accurately reflect the average molecular mass of the
individual polymer chains, which is the desired quantity.
Sufficient dilution, in this case, online, insures that the
scattering is dominated by the Mw of the polymers, and not
inter-polymer effects.
[0156] Automatic Characterization of Batch Solutions of Polymer
[0157] The two vessel scheme has been used by Strelitzki and Reed
(ref. 7) to automate batch characterization of polymer solutions,
in conjunction with refractive index, multi-angle LS and
viscometric detectors. The advantages over the manual dilution
methods have been detailed above.
[0158] Determination of the Electroviscous Effect.
[0159] The two vessel scheme has also been used by Strelitzki and
Reed (unpublished results) to investigate the electroviscous effect
in polyelectrolyte solutions. To accomplish this, polyelectrolytes
(hyaluronic acid, xanthan and poly(styrene sulfonate) were used)
were dissolved at about 1 mg/ml in a low strength NaCl solution
(these generally ran the range from 0M to 0.001M NaCl) and placed
in the first vessel. A stock solution of salt at the same
concentration as in the first vessel was placed in the second
vessel, and the gradient programmer was set to perform a continuous
dilution of the polyelectrolyte from its full concentration in the
first vessel to zero, or vice versa. Because the original
polyelectrolyte solution also contains the counterions of the
polyelectrolyte, the actual ionic strength of the solution is
higher than the nominal ionic strength due to the added NaCl. As
dilution of the polyelectrolyte takes place with pure solvent of
the same nominal ionic strength, the total ionic strength of the
diluted polyelectrolyte solution actually decreases, since the
counterion concentration decreases with dilution, which leads to
the electroviscous effect. Typical online, electroviscous data for
hyaluronic acid is shown in FIG. 18.
[0160] Table of Abbreviations
[0161] A.sub.2=second virial coefficient
(cm.sup.3.times.Mole/g.sup.2)
[0162] C=concentration (in g/cm.sup.3)
[0163] FET=field effect transistor
[0164] g/cm.sup.3=grams per cubic centimeter
[0165] g/mole=gram per mole
[0166] He--Ne laser=Helium Neon laser
[0167] HTDSLS=Heterogeneous time dependent static light
scattering
[0168] HPLC=High Pressure Liquid Chromatography
[0169] kD=kiloDalton (1,000 grams per mole)
[0170] .lambda.=wavelength
[0171] LS=light scattering
[0172] M=molarity
[0173] M.sub.w=weight average molecular mass (grams per mole)
[0174] mg/ml=milligram per milliliter
[0175] ml=milliliter
[0176] ml/min=milliliter per minute
[0177] mV=millivolt
[0178] mW=milliwatt
[0179] nm=nanometer
[0180] PVP=poly(vinyl pyrrolidone)
[0181] <S.sup.2>=mean square radius of gyration (in
Angstrom.sup.2, nm.sup.2, or cm.sup.2)
[0182] SEC=Size Exclusion Chromatography
[0183] SLS=Static light scattering
[0184] TDSLS=Time dependent static light scattering
[0185] VP=vinyl pyrrolidone
[0186]
2 PARTS LIST: The following is a list of parts and materials
suitable for use in the present invention: 10 optical assembly of
the preferred embodiment of the present invention 20 ring member
assembly of a first embodiment of the present invention 21 ring
member of the ring member assembly 20 of the first embodiment of
the present invention (such as nylon, polycarbonate, anodized
aluminum, kevlar or ceramic) 22 chamber of ring member 21 23
incident beam window of ring member 21 (e.g. Edmund scientific
borosilicate or sapphire circular windows) (e.g., 5 mm diameter, 2
mm thick) 24 beam dump window of ring member 21 (same as 23, or
similar) 31 incident beam (provided by, for example, a vertically
polarized 5 mW diode laser commercially available from Lasermax
Inc., Rochester, NY) 32 beam dump (such as a window or prism
followed by a Rayleigh horn or a detection fiber) 41 optical fibers
(such as optical fibers of 100, 150 and 300 micron core diameter,
commercially available from Polymicro Technologies as parts
FVP100110125, FVP 150165180 and FVP300330370, respectively.) 42
holes for optical fibers 41 43 optical harness (e.g. the fibers can
be `braided` together with semiflexible plastic tubes and covered
with a rugged sheath, such as is commonly done for
telecommunication fiber bundles) 44 ends of the optical fibers 41
45 outer protective sheathing 51 sample solution (for example 1
mg/ml Polyvinylpyrrolidone in water) 52 container for sample
solution 51 (glass beaker, for example) 61 handle for ring member
assembly 20 (stainless steel, for example) 62 light source (such as
a diode laser) 63 converging lens 70 flow mode assembly of the
present invention 71 end piece of flow mode assembly 70 (made of
nylon, ceramic, anodized aluminum, or kevlar, for example) 72
hydrodynamic tapered flow channels in end pieces 71 73 HPLC tubing
and fittings (e.g. Rainin Corp., or ISCO) 74 O-rings 75 retaining
bolts 80 fill mode assembly of the present invention 81 base plate
(made of plastic or anodized aluminum, for example) 91 sample
solution (1 mg/ml polyvinylpyrrolidone in water, for example) 92
container for sample solution 91 (glass, for example) 100 integral
chamber assembly of the present invention 101 integral chamber wall
(such as stainless steel, black anodized aluminum, ceramic, Teflon,
nylon, polycarbonate, or other plastics) 102 integral chamber 111
photodiode assembly (containing Hammamatsu Corp photodiodes, for
example) 112 computer for data collection and analysis (such as an
IBM personal computer clone such as a Starion 919 from Digital
Equipment Corp.) 113 strain relief loop 114 cowl 115 acceptance
angle of fiber optic 41 in FIG. 8 116 acceptance angle of fiber
optic 41 in FIG. 9 in water 117 acceptance angle of fiber optic 41
in FIG. 9 in toluene 118 optical detectors 161 base plate
[0187] References (Incorporated Herein by Reference)
[0188] 1. Zimm, B. H. J. Chem. Phys., 16, 1093-1116 (1948)
[0189] 2. W. F. Reed "Time-dependent light scattering from singly
and multiply stranded linear polymers undergoing random and endwise
scission", J. Chem. Phys., 103, 7576-7584, (1995)
[0190] 3. S. Ghosh and W. F. Reed "New Light Scattering Signatures
from Polymers undergoing Depolymerization w. App. to Proteoglycan
Degradation" Biopolymers, 35, 435-450 (1995)
[0191] 4. W. F. Reed "Time-Dependent Processes in Polyelectrolyte
Solutions", invited chapter for Berichte der Bunsen-Gesellschaft
special volume on Polyelectrolytes, 100, 6, 1-11, 1996
[0192] 5. Ruth Schimanowski, Roland Strelitzki, David A. Mullin and
Wayne F. Reed "Heterogeneous Time Dependent Static Light
Scattering", Macromolecules, in press (accepted Aug. 6, 1999)
[0193] 6. Fabio H. Florenzano, Roland Strelitzki and W. F. Reed,
"Absolute, Online Monitoring of Polymerization Reactions",
Macromolecules, vol. 31, no. 21, 7226-7238, 1998
[0194] 7. Roland Strelitzki and Wayne F. Reed, "Automated Batch
Characterization of Polymer Solutions by Static Light Scattering
and Viscometry", J. App. Polym. Sci., 73, 2359-2368 1999
[0195] All measurements disclosed herein are at standard
temperature and pressure, at sea level on Earth, unless indicated
otherwise. All materials used or intended to be used in a human
being are biocompatible, unless indicated otherwise.
[0196] Attached as Appendix A to parent patent application Ser. No.
08/969,386 is data collection and storage software which can be
used as a basis for more complex software to perform absolute
macromolecular characterization and electronically filter out,
count, and characterize large scattering particles.
[0197] As used herein, "large scattering particle" (LSP) means an
individual particle which would produce scattered light greater
than the noise level of the detector (in FIG. 13, for example, the
noise level is around 0.04V and the large scattering particles are
indicated at about 12 seconds, 26 seconds, 38 seconds, and 46
seconds, in addition to other locations). A LSP could be unwanted
impurities, aggregates of the polymer or colloid being studied, or
an integral part of the solution.
[0198] The detectors and interface operate at a rate fast enough to
resolve the residence time of a large scattering particle in the
scattering volume. The interface between the photodetector and the
computer can be a voltage-converting or a current-converting
interface.
[0199] Preferably, the scattering volume is chosen such that the
number of large scattering particles is small enough to not prevent
absolute macromolecular characterization of the substance being
studied, and preferably small enough to not significantly interfere
with absolute macromolecular characterization of the substance
being studied. For example, the average number of LSPs in the
scattering volume can be less than 1000, preferably less than 500,
more preferably less than 200, even more preferably less than 100,
still more preferably less than 50, even more preferably less than
20, even more preferably less than 10, most preferably less than 5.
The average number of LSPs in the scattering volume can be even 0
to 1.
[0200] The present invention is a relatively inexpensive, simple,
versatile apparatus for use in SLS and TDSLS.
[0201] The size range of detectability can be, for example, 20
Angstroms to 100 microns. The size range of detectability should
run from about 20 Angstroms to 100 microns, with useful
measurability in the range from 20 Angstroms to 2 microns, and a
preferred range from about 20 Angstroms to 5000 Angstroms. Stated
in terms of molar mass, the detectable range of particles should
run from about 500 g/mole to 10.sup.14 g/mole, with useful
measurability in the range of 500 g/mole to 10.sup.9 g/mole, with a
preferred range from about 1000 g/mole to 10.sup.7 g/mole.
[0202] The transmission means for transmitting light from the light
detection means to the photodetectors is preferably of a sufficient
length and flexibility to allow the submersible probe to be
submersed in the fluid to be sampled without submersing the
photodetectors, and to allow the other probes to be remote from the
photodetectors, which is helpful when the probe is to be used in
harsh environments which might damage the photodetectors and
associated electronics.
[0203] As used in the claims, "light source" can refer to a window,
lens, or optical fiber, for letting light in from a light
generator, such as a laser.
[0204] Novelty of the Apparatus of the Invention Related to
Dilution Apparatus
[0205] The novelty of one aspect of the present invention consists
in providing an automatically and continuously diluted or mixed
stream of polymer from polymer-containing vessels whose viscosity
is too high to allow current and conventional devices to provide
such streams.
[0206] While several devices for automatic dilution have been
patented, none appear to work over the wide viscosity ranges
encountered in the types of polymer systems of main interest in
this field. Most that are applicable in the polymer area are more
concerned with sampling and diluting relatively low viscosity
fluids containing a large amount of particulate matter; e.g.
polymer latex, microemulsions, and so on. For example, Garcia-Rubio
et al. (U.S. Pat. No. 5,907,108) have disclosed a sampling and
dilution system that provides a high degree of dilution, but is
oriented towards, e.g. emulsion polymerizations, where reactor
fluid viscosity is not high. Other devices include those of Nicoli
and Elings (U.S. Pat. No. 4,794,806), which again is oriented
towards low viscosity fluids. Bysouth's invention (U.S. Pat. No.
5,801,820) is chiefly concerned with dilution of concentrated, but
not viscous, liquids for absorption spectroscopic measurement.
[0207] Likewise, commercially available mixing units, such as the
ISCO, Waters, and the Dionex, are all incapable of mixing fluids
whose viscosities exceed two or three hundred cP. These latter are
all piston pumps, which cavitate and lose prime when the fluid
viscosity becomes high, and/or bubbles are introduced into their
input.
[0208] Thus, the current invention fills a need not currently
filled by existing patents or commercial devices.
[0209] All US Patents mentioned herein are incorporated herein by
reference.
[0210] Specific Embodiments
[0211] The device consists of the following elements: A pump for
withdrawing liquid from the polymer vessel, a pump for withdrawing
solvent from a solvent reservoir, a scheme for homogeneously mixing
the reactor contents and the solvent, and a means of pumping the
mixed solution to the detector train. Often times a secondary
dilution stage will be used to achieve even higher levels of
dilution than is feasible with a single stage.
[0212] Means of withdrawing the liquid from the reactor preferably
include, but are not limited to, peristaltic, lobe, gear and screw
pumps, and their variants, and certain specialty piston pumps (such
as are commercially available from Fluid Metering, Inc. of Syosset,
N.Y.). Means of pumping solvent include any of the above mentioned
pumps, but also piston and other pumps suitable for pumping low
viscosity liquids. Means for homogeneously mixing include
micro-mixing `T` type chambers, actively stirred microchambers,
mixing chambers with static mixing elements, or any combination of
these. The homogeneously mixed solution can be pumped to the
detector train with any of the above mentioned pumps, including the
low viscosity handling types, since the mixed solution will be of
low viscosity.
[0213] The following are possible embodiments.
[0214] Recirculating Gear-Pump Based Device:
[0215] The gear pump is fed from the reactor by gravity and pumps
the reactor liquid at a desired rate, such as 0.1 to 10 ml/minute,
and recirculates the majority of the liquid back into the reactor,
whereas a small amount is diverted, either continuously or in
discrete pulses, towards the mixing chamber. The diversion to the
mixing chamber can occur continuously by providing a `Y` fitting,
such that the resistances of the return and mixing chamber feed
paths have the desired relationship to feed the mixing chamber at
the desired rate. Alternatively the `Y` fitting can be replaced by
a solenoid valve with a diverter outlet, allowing pulses of
material to be output to the chamber while the diverter port is
electromechanically opened. This solenoid valve would be under the
control of a programmable logic controller (PLC).
[0216] In turn, the solvent is pumped to the mixing chamber by any
type of pump desired, such as a peristaltic pump. The mixing
chamber might receive the reactor/solvent flows with partial
pre-mix, e.g. by interposing a micro-mixing `T` between the two
pumps and the mixing chamber, or the chamber might accept the flows
directly.
[0217] The contents of the mixing chamber can feed the detector
train directly, or a second dilution stage might be used.
[0218] Recirculating Peristaltic Pump Based Device:
[0219] When viscosity does not become extremely high it may
sometimes be desirable to substitute a peristaltic or other lower
viscosity handling pump in place of the gear or screw pump. Two
main reasons for doing this are 1) a peristaltic pump can prime
itself and withdraw material from a reactor without gravity feed,
and 2) the peristaltic pumps are often more economical than gear
pumps.
[0220] Non-Recirculating Designs.
[0221] There are cases where recirculation may not be desired or
may not be necessary. In the former category might be found certain
high purity products, normally falling under governmental food and
drug guidelines, which cannot be re-introduced into a vessel or
reactor once withdrawn. In the latter category may fall cases where
lag-time is not a critical issue, and many minutes, possibly tens
of minutes, constitute acceptable lagtimes. In such cases the
mixing chamber can be fed directly by the reactor withdrawal pump,
at suitable low flow rates.
[0222] Pre-Mixing and Secondary Mixing/Diluting Schemes
[0223] Performing pre-mixing can be advantageous in certain
circumstances. For example, the reactor may contain highly
corrosive materials that should be diluted to a certain level
before allowing it to pass through any downstream pumps. Or, a
large dilution factor may be desired, in which case large dilutions
can be efficiently made as the product of two or more separate
dilutions. A predilution scheme allows both low and high pressure
mixing, since the first mixing stage can be made at low pressure,
exhaling bubbles in the process, and a second stage mixing can be
done at high pressure. Also, predilution can in some instances
reduce lag-time, especially if the low pressure mixing chamber is
allowed to fill more rapidly than it is pumped out by the detector
feed pump. In this case, there will normally be an overflow of
mixing chamber liquid to waste.
[0224] Y-Diversion Scheme Versus Solenoid Valve Diversion
Scheme
[0225] The `Y`-diversion scheme is based ideally on Poisseuille's
law which states that the flow rate Q of a liquid of viscosity
.eta. through a pressure drop .DELTA.P along a capillary of radius
R and length L, is given by 5 Q = R 4 P 8 L
[0226] The pressure difference for each outlet side of the L is the
pump output pressure minus the outlet pressure of the side. The
capillaries can be represented as two resistors in parallel, which
divide the flow rate of the pump outlet. For the case where both
the mixing chamber and the reactor return are at atmospheric
pressure .DELTA.P is the same and so the relative flow rates are
determined simply by L and R of each capillary. In all cases, the
ratios of the two resistances is independent of the changing
reactor viscosity .eta., which ensures a constant flow rate of
reactor liquid to the mixing chamber. The over-riding advantage of
this method is its simplicity, as it eliminates an
electromechanical device (the solenoid valve), which should give it
greater reliability in harsh environments, such as near industrial
reactors. Its drawback is that the ratio of flow rates of
recirculation to chamber is fixed, and hence not changeable by
programming. On the other hand, the absolute flow rate to the
mixing chamber can be changed simply by changing the gear pump flow
rate. Deviations from Poisseuille's law can be corrected
empirically. At any rate, it is expected that the ratio of
recirculation to chamber feed flow rates will be measured.
[0227] Mixing Chamber Considerations
[0228] ACOMP experiments have demonstrated the deleterious effects
of bubbles entering the detector train. In fact, bubbles in the
detector train must be avoided at all cost if reliable operation
and online analysis is to be maintained. The best safeguard against
bubbles is to perform the mixing of reactor liquid and solvent at
low pressure, so that the bubbles are exhaled and vented to
atmosphere, thus never entering the pump line to the detectors.
[0229] The mixing chamber itself can be of the active or passive
type. In either case, reactor fluid and solvent are led into the
chamber by tubing, either individually, or pre-mixed, where mixing
and any exhalation of bubbles takes place. An active mixer employs
a means of stirring, for example any sort of micro-propeller
mounted on a rotating shaft. Heating is optional. The mixed fluid
is automatically withdrawn from the chamber and pumped through the
detector train.
[0230] In a passive mixing chamber the reactor fluid and solvent
are led in either separately, or pre-mixed, and the static mixing
elements in the chamber ensure that mixing occurs.
[0231] Optionally, the mixing chamber can have a level sensor,
which, when coupled to a PLC will maintain a steady level. A
simpler embodiment is to simply equip the chamber with an overflow
outlet to waste, for maintaining a given level.
[0232] Lag-Time and Response Time Considerations
[0233] Inevitably, there is a lag-time between the reactor and the
detectors. Normally, a lag-time of up to several minutes is quite
acceptable, both for laboratory and plant-level ACOMP. The length
of the lag-time is purely a question of pump, chamber and tubing
volumes, and flow rates. In principle it can be made almost
arbitrarily small. For example, in a recirculating system, fresh
material can be continuously circulated to the diversion (of either
`y` or solenoid types) at a rate of several ml/min. This means that
fresh reactor fluid presents itself to the diversion within seconds
of withdrawal from the reactor. If the tubing connection to the
chamber has low dead volume (e.g. a few tens of microliters), then
the fresh reactor liquid will enter the chamber within seconds of
reaching the diversion. The time from the mixing chamber to the
detectors can likewise be on the order of seconds, so that the
entire lag-time can easily be kept under one minute.
[0234] The net dead volume from the diversion to the detectors will
determine the system response time, the dead volume of the mixing
chamber being the single largest source. Since the average, ideal
residence time is mixing chamber volume divided by the flow rate of
withdrawal from the chamber, the response time can be kept low. For
example, withdrawing from a 0.5 ml chamber at a rate of 2 ml/min
gives a 15 second response time. The response time sets the minimum
time interval over which a change in the state of reactor fluid can
be measured, whereas the lag-time is the delay between sampling an
instantaneous state and making a measurement on it.
Conditioning Stages
[0235] Because this device is designed to work on a wide variety of
polymeric and colloidal fluids, it will be desirable in certain
instances to provide further sampling conditioning before the
diluted fluid enters the detection train. Examples follow:
[0236] Debubbling. This is one of the most common forms of sample
conditioning, and is most easily accomplished by providing a
micro-mixing chamber vented to atmospheric pressure, so that
bubbles are exhaled.
[0237] Monomer and other small molecule evaporation. There will be
times when it is not desirable to have monomer in the dilution
stream along with polymer. An example is the case where there is
not a significant spectroscopic difference between the monomer and
polymer, so that the relative concentrations are not easily
determined. Because of the small volumes used by the device it is
easy to provide a small, heated, vented chamber for rapid
evaporation of small molecules either before or after the dilution
stage.
[0238] Breaking self-organizing microstructures. For monitoring
inhomogeneous phase reactions, such as those occurring in
self-organizing microstructures (SOM) like microemulsion or
micellar polymerization, it will be necessary to release the
contents of the SOM into the diluted sample stream. This might
occur by changing the solvent polarity, ionic content,
hydrophobicity, etc. in a conditioning module.
[0239] Filtration. Many reactors have large particles, such as
microcrystals, microgels, bacteria, aggregates, etc., which are a
desired or undesired part of the reaction itself. In many cases it
will be necessary to remove such particulates in order for the
detector train to function properly. Hence, a filtration device
mounted in line with the device may often be required. In some
cases hydrophobic or hydrophilic filtration may be used to block a
solvent component from entering the detector train.
[0240] In some cases filtration may occur after certain detectors
but before others. For example, in the Heterogeneous Time Dependent
Light Scattering (HTDSLS) case.sup.6 it may be necessary or
desirable to let large particles (e.g. up to several microns) pass
through the light scattering detector, and possibly also the
viscometer. Such particles, however, normally should not be let to
flow through the RI and UV detectors, as it might damage them or
lead to spurious signals. In such a case, a filter can be placed
after the light scattering (and viscometer, if desired) but before
the RI and UV detectors.
[0241] Sample dissolution. In some cases, e.g. fluidized bed
reactors and pressurized vessels producing slurries, the polymer of
interest may be produced in particulate or pelletized form. The
conditioning stage in this instance would dissolve the solid or
slurry material prior to or simultaneous to diluting it with
solvent.
[0242] FIG. 19 shows a typical embodiment of the apparatus of the
present invention; a two stage, recirculating mixer. A pump G is
capable of handling high viscosities; pump G could be a gear,
screw, or lobe pump. In the case of intermediate viscosities a
peristaltic pump can also be used. It extracts reactor fluid, with
a solute concentration Cr, at a flow rate of Qr. The majority of
this flow recirculates back to the reactor, whereas a desired
fraction is delivered to the mixing chamber (M) via a diverter (D),
at an average flow rate of Qc. The diverter can be of either an
active or passive type. A passive type can be simply a `Y`, where
the lengths and inside diameters of the capillaries going from the
Y back to the reactor and into M controls the fluid flow split. An
active diverter D might be a three-way solenoid valve, which
normally delivers back to the reactor, but can be actuated by a
programmable logic controller (PLC) or similar electronic device,
so as to periodically divert flow into M, to achieve the average
Qc. Pump P1 withdraws solvent from a solvent reservoir at a rate
QS1 and delivers it to M, where both the reactor fluid and solvent
are mixed, yielding a concentration 6 Cc = Cr Qc Qc + Qs1
[0243] At this point, a single stage mixer would simply feed the
detector train with fluid of concentration Cc, via pump P2 at a
flow rate Qp2. In the two stage dilutor the compound secondary
stage S contains a third pump P3 that withdraws solvent from the
solvent reservoir at a rate Qs2. The outlets of P2 and P3 are mixed
with a very low volume microbore high pressure mixing T (e.g.
Upchurch, Inc.), for example, or other passive or active mixing
device. The flow rate to the detector train is hence Q=Qs2+Qp2, and
the concentration of solute reaching the detector train is 7 Cd =
Cc Qp2 Qp2 + Qs2
[0244] The detector train in this embodiment consists of a single
or multi-angle light scattering detector LS, a refractometer RI, a
viscometer V, and an ultra-violet/visible spectrophotometer UV.
Other types and combinations of detectors are possible. For
example, one or more of these measuring devices could be
omitted.
[0245] A non-recirculating embodiment would simply withdraw reactor
fluid at a rate Qc and feed M directly. All other flow rates and
concentrations remain as stated above. The main difference in this
approach is that there will be a longer delay time between the
sampling of a fluid element and its measurement by the detector
train.
[0246] An active mixing element M, such as a rotary vane turned by
a miniature motor, is shown in FIG. 19. In the case of low
viscosity fluids a passive element may be substituted. Mixing
element M is normally vented to atmosphere so as to allow any
bubbles coming from the reactor to be exhaled, and not drawn into
the detector stream. An active or passive overflow O, and/or a
level sensor, is preferably included in the apparatus (see FIG.
19). In the latter case, the level sensor will work in conjunction
with the PLC to control an active D. In this case, a solvent
recirculation loop may be introduced, whereby a second active
diverter, also operated by the PLC, will deliver, at intervals, the
desired average Qs1. In the case of an active overflow without a
level sensor, a certain amount of the mixed fluid in M will be
pumped away by another low viscosity pump at a rate Qw, such that
Qw+Qp2=Qc+Qs1. The volume V, of M, together with the combined flow
rate Qs1+Qc determines the average residence time t.sub.r, (and
hence response time of the chamber), of a fluid element in the
mixing chamber, according to 8 t r = V Qc + Qs1
[0247] t.sub.r sets the lower limit of the time for a reaction to
occur that can still be monitored by ACOMP. Typically, t.sub.r is
on the order of tens or hundreds of seconds. If the chamber is fed
in pulses by an active diverter(s) at intervals of .DELTA.t, then M
smoothes out the discrete injections of reactor fluid and/or
solvent as long as t.sub.r>>.DELTA.t. Commercial solenoid
type diverters typically have response times on the order of
milliseconds or tens of milliseconds, so the latter criterion is
not hard to satisfy, and so the total solute concentration in M can
be maintained constant, such that the detector signals do not
display peaks or pulsations due to concentration fluctuations in
M.
[0248] Notes:
[0249] 1) P1, P2 and P3 do not have to pump highly viscous liquids,
G being the only high viscosity pump in the embodiment. P1 does not
have to work against any significant back-pressure since M is
vented to atmosphere, and so a very inexpensive peristaltic,
piston, diaphragm, or other type pump can be used. P2 and P3 must
be able to pump the low viscosity, mixed sample fluid against the
detector train back-pressure, typically on the order of 20 psi to
1000 psi. Many commercially available piston pumps exist for this
application.
[0250] 2) CM in the drawing is a conditioning module. It can
perform functions such as heating the reactor fluid to evaporate
solvent and/or monomer, or filtering the reactor fluid. CM can also
be place at other points in the diagram, such as at the outlet of
M.
Preliminary Data
[0251] I) Non-Recirculating, Two Stage Mixer with a Peristaltic
Pump for G.
[0252] In this experiment (see FIG. 20) a Greylor peristaltic pump
G (Qc=0.08 ml/min) withdrew reactor fluid from a polystyrene
polymerization reaction to feed M. In this reaction, 94% by weight
styrene was mixed with 6% by weight ethylbenzene, and a free
radical initiator (Luperox TAEC, Atofina), was used at 517 ppm, and
the reaction was carried out at 117.degree. C. A second Greylor
pump P1, operating at Qs1=0.8 ml/min was used to feed solvent
(tetrahydrofuran, or THF) to M. P2 and P3 were both Agilent 1100
isocratic HPLC (high pressure liquid chromatography) pumps. Qp2 was
set at 0.2 ml/min, and Qs2 at 1.8 ml/min, so that Q=2.0 ml/min,
feeding the detector train with a solute concentration of
approximately Cd=0.01 g/cm.sup.3; i.e. roughly a 100 fold dilution.
The reaction proceeded until the final viscosity was several
thousand cP.
[0253] The mixing chamber was a 2 cm diameter scintillation vial
atop a magnetic stirrer. A magnetic stir bar in the vial provided
the mixing action. A vented cap was made for the vial which held
the tubes providing Qc, Qs1, Qw, and Qp2.
[0254] The detector train consisted of a homebuilt, single
capillary viscometer V, a prototype multi-angle light scattering
unit of the inventor's design (U.S. Pat. No. 6,052,184) LS, a
Waters 410 RI, and a Shimadzu SPD-10AV UV. These instruments and
methods have been previously described (see endnotes 1-13).
[0255] Over the first 2500 s pure THF flowed through the system and
established the baseline of each detector. At 2500 s Cd of
unreacted styrene in the detector began to flow. The increase in UV
and RI show the arrival of styrene in the THF at the detector
train. V and LS (90 degree signal shown, data from six other angles
were simultaneously collected) do not respond to the monomeric
styrene. Initiator was added at about 8,500 s. At 10,000 s the
beginning of the polymerization is seen via the increase in LS and
V. At the end of the reaction the fall off in each of the detector
signals show that the reactor fluid viscosity due to the
polystyrene produced is too high for G. The delay time in this
configuration was quite long, and was estimated at about 20
minutes.
[0256] II) Non-Recirculating, Two Stage Mixer with a Gear Pump for
G.
[0257] The second experiment shown here (see FIG. 21) was also a
styrene polymerization reaction, under the same conditions as the
first. The main difference was the use of a custom-built Zenith
Corporation gear pump (with stepper motor drive) as G.
[0258] The results of the gear pump are clearly superior to those
from the peristaltic pump. The RI is much more steady, showing the
ability of the gear pump to pump the higher viscosities, and the
ability of the mixing chamber to deliver a smooth, well-mixed
fluid. Even at the highest viscosities the gear pump continued to
deliver reactor fluid to M, whereas the peristaltic pump lost its
ability to pump. The delay time with the gear pump was
substantially lower, on the order of 5 minutes.
[0259] Another example of data collected using the same pumping
scheme shown for the polystyrene data above is now given. The
reaction was a free radical polymerization of two water soluble
vinyl polymers at a high weight concentration in pure water. The
starting viscosity was around that of water. By the end of the
polymerization the viscosity in the reactor was over 100,000 times
greater than that of water. The flow rate was 2.0 ml/minute. A
50-fold dilution of the reactor contents occurred in the low
pressure mixing chamber, and a subsequent 10-fold dilution in the
high pressure mixing chamber.
[0260] FIG. 22 shows raw data for the reaction from the detector
train, consisting of a homebuilt viscometer, a Brookhaven
Instruments BI-MwA seven angle light scattering detector, a
Shimadzu ultra-violet absorption spectrometer (UV) set to 234 nm,
and a Waters 410 refractive index detector.
[0261] Pure solvent (water) flows through the detector train
initially, after which the diluted monomer stream flows, up until
about 7,000 s, at which point the results of initiating the
polymerization about 15 minutes earlier (15 minutes is the
approximate delay time from reactor to detector train) are seen.
The 90 degree light scattering (LS) data are shown (data from the
other six angles are not shown), which reflects the increasing
concentration of polymer as the monomer is converted during the
reaction. The refractometer rises modestly during the reaction,
reflecting the fact that the differential index of refraction of
the polymer is greater than that of the monomer. The decay of the
ultra-violet absorption at 234 nm directly measures the conversion
of the monomer, since the absorption is due to the double bond in
the monomer, which is lost once incorporated into the polymer, and
the absorption is lost. The rise in the viscometer shows the
increase in polymer concentration.
[0262] These raw data were evaluated according to the methods of
Florenzano et al..dagger..dagger. Fabio H. Florenzano, Roland
Strelitzki and W. F. Reed, "Absolute, Online Monitoring of
Polymerization Reactions", Macromolecules, vol. 31, no. 21,
7226-7238, 1998
[0263] FIG. 23 shows the fraction of monomer converted as a
function of time. Full conversion of monomer occurs by the end of
the reaction.
[0264] FIG. 24 shows the reduced viscosity of the polymer, and the
weight averaged polymer mass M.sub.w. Because the solution is so
dilute in the detector train (0.0004 g/ml), the reduced viscosity
measured is very close to the value of the intrinsic viscosity
(e.g. see Grassl and Reeds.dagger-dbl.), which is purely a
characteristic of the individual polymer chains' mass,
conformation, and hydrodynamic interaction with the solvent
(water). It is seen that both M.sub.w and reduced viscosity
increase during the reaction, although with different trends. This
reflects the fact that M.sub.w and reduced viscosity have separate
functional relationships to the polymer population's mass
distribution. It is also noted that these quantities, which measure
their respective averages of the entire polymer population at any
instant during conversion, need not
increased.sup.1,.sctn..dagger-dbl. Bruno Grassl and Wayne F. Reed,
"Online polymerization monitoring in a continuous tank reactor",
Macromolecular Chemistry and Physics, 203, 586-597, 2002 .sctn. A.
Giz, H. Giz, J. L. Brousseau, A. Alb, and W. F. Reed, "Kinetics and
Mechanism of Acrylamide Polymerization by Absolute, Online
Monitoring of Polymerization Kinetics", Macromolecules, vol. 34, 5,
1180-1191, 2001
[0265] Examples of polymerization reactions and dilution solvents
are as follows.
[0266] Typical solvents which can be used for dilution include, but
are not limited to: water and other aqueous solvents such as those
containing simple and complex electrolytes and buffering agents.
Also a wide variety of non-aqueous solvents, toluene, chloroform,
tetrahydrofuran, butyl acetate, dimethyl sulfoxide, ether,
methanol, ethanol, other alcohols, ethylene glycol, n-methyl
pyrrolidone, etc., as well as mixtures of such solvents.
[0267] Typical polymer reactions that can be monitored by ACOMP
include:
[0268] 1) Chain growth reactions, such as those initiated by free
radicals, or in anionic, controlled radical, atom transfer radical,
and other polymerization reactions, to produce such polymers as
polystyrene, polyacrylamide, poly(vinylpyrrolidone), poly(butyl
acrylate), etc.
[0269] 2) Step growth reactions, such as those used to produce such
polymers as polyurethane, polyamines, nylons, etc.
[0270] 3) Polymerization reactions wherein copolymers are formed,
whether such copolymers consist of two or more comonomers, and
whether they are formed as strictly alternating, random, blocks,
grafts, etc.
[0271] 4) Polymerization reactions in which a pre-dissolution stage
may be necessary as part of the conditioning system. Such examples
may include cases where there is a slurry formed, such as from a
high pressure or phase separating reactor, or solid polymer pellets
are formed, such as from a fluidized bed reactor.
[0272] 5) Polymerization reactions whether they occur in batch or
continuous reactors.
[0273] 6) Degradation reactions in which agents such as acids,
bases, ultrasound, enzymes, heat, radiation, etc. degrade
biological polymers such as polysaccharides, proteins, and nucleic
acids, or synthetic polymers, such as those mentioned above.
[0274] `Computer` used throughout the description of this invention
refers to any device capable of receiving signals from detectors
described herein, and performing the required data reduction and
analysis on these signals. Hence, `computer` can refer to any
commercially available computer (e.g. such as those sold by IBM,
Dell, Apple, etc.), including workstations (e.g. Sun Microsystems),
as well as any microprocessor-based device whether commercially
available or designed specifically for the data acquisition and
analysis functions described herein.
[0275] All measurements disclosed herein are at standard
temperature and pressure, at sea level on Earth, unless indicated
otherwise. All materials used or intended to be used in a human
being are biocompatible, unless indicated otherwise.
[0276] The foregoing embodiments are presented by way of example
only; the scope of the present invention is to be limited only by
the following claims.
* * * * *