U.S. patent application number 11/646856 was filed with the patent office on 2007-05-31 for continuous process for the production of combinatorial libraries of modified materials.
This patent application is currently assigned to 3M Innovative Propeties Company. Invention is credited to Jeffrey J. Cernohous, Ryan E. Marx, James R. McNerney, James M. Nelson.
Application Number | 20070122915 11/646856 |
Document ID | / |
Family ID | 31187533 |
Filed Date | 2007-05-31 |
United States Patent
Application |
20070122915 |
Kind Code |
A1 |
Nelson; James M. ; et
al. |
May 31, 2007 |
Continuous process for the production of combinatorial libraries of
modified materials
Abstract
A system is provided wherein a devolatilizing reactor is used to
make combinatorial libraries of materials. Examples of suitable
reactors include continuous high viscosity devolatilizers and
continuous devolatilizing kneaders.
Inventors: |
Nelson; James M.;
(Roseville, MN) ; Marx; Ryan E.; (Cottage Grove,
MN) ; Cernohous; Jeffrey J.; (Hudson, WI) ;
McNerney; James R.; (Inver Grove Heights, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Propeties
Company
|
Family ID: |
31187533 |
Appl. No.: |
11/646856 |
Filed: |
December 28, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10211219 |
Aug 2, 2002 |
7157283 |
|
|
11646856 |
Dec 28, 2006 |
|
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Current U.S.
Class: |
436/518 |
Current CPC
Class: |
C40B 40/14 20130101;
B01J 2219/0059 20130101; B01J 2219/00698 20130101; Y10T 436/25
20150115; B01J 2219/00481 20130101; B01F 15/0404 20130101; B01J
2219/00011 20130101; Y10T 436/2575 20150115; B01J 2219/0004
20130101; B01J 2219/00166 20130101; B29B 7/007 20130101; B01J
2219/00495 20130101; B01J 2219/00033 20130101; B01J 2219/00286
20130101; B01J 2219/00722 20130101; C40B 60/14 20130101; B01J
2219/00186 20130101; B01J 19/0046 20130101; B01J 2219/00189
20130101; B01J 2219/00716 20130101 |
Class at
Publication: |
436/518 |
International
Class: |
C40B 30/06 20060101
C40B030/06; C40B 40/04 20060101 C40B040/04 |
Claims
1. A continuous method of making a combinatorial library of
materials comprising: providing a plug flow mixing apparatus having
a high shear environment and devolatilization capabilities;
continuously introducing into the mixing apparatus a composition
containing at least one polymer that can be modified by a
thermally-induced reaction into the reactor; exposing the
composition to a high shear environment; and introducing or
changing over time at least one variable affecting the properties
of the at least one polymer that can be modified to produce a
combinatorial library of materials; wherein the thermally-induced
reaction comprises the elimination of isobutylene and water from
methacrylic and acrylic esters to produce one or both of acid and
anhydride functionalities.
2. The method of claim 1, wherein the composition is exposed to a
temperature of about 100.degree. C. to about 180.degree. C. while
it is exposed to a high shear environment.
3. The method of claim 1, further comprising evaluating the
materials of the library.
4. The method of claim 1, wherein the composition when introduced
into the apparatus comprises 90 weight % solids or less.
5. The method of claim 1, wherein the composition when introduced
into the apparatus comprises 80 weight % solids or less.
6. The method of claim 1, wherein the exposed functional group is
capable of undergoing a grafting reaction.
7. The method of claim 1, wherein the reaction is catalyzed.
8. The method of claim 7, wherein the reaction is
acid-catalyzed.
9. The method of claim 7, wherein the reaction is
base-catalyzed.
10. A continuous method of making a combinatorial library of
materials comprising: providing a plug flow mixing apparatus having
a high shear environment and devolatilization capabilities;
continuously introducing into the mixing apparatus a composition
containing at least one polymer that can be modified by a
thermally-induced reaction into the reactor; exposing the
composition to a high shear environment; and introducing or
changing over time at least one variable affecting the properties
of the at least one polymer that can be modified to produce a
combinatorial library of materials; wherein the thermally-induced
reaction comprises the elimination of trialkylsilanes from
trialkylsiloxy end or side group containing polymers to produce a
library of hydroxyl end or side group functional polymers.
11. The method of claim 10, wherein the composition is exposed to a
temperature of about 100.degree. C. to about 180.degree. C. while
it is exposed to a high shear environment.
12. The method of claim 10, further comprising evaluating the
materials of the library.
13. The method of claim 10, wherein the composition when introduced
into the apparatus comprises 90 weight % solids or less.
14. The method of claim 10, wherein the exposed functional group is
capable of undergoing a grafting reaction.
15. The method of claim 10, further comprising an in situ chemical
reaction at the functional group.
16. A continuous method of making a combinatorial library of
materials comprising: providing a plug flow mixing apparatus having
a high shear environment and devolatilization capabilities;
continuously introducing into the mixing apparatus a composition
containing at least one polymer that can be modified by a
thermally-induced reaction into the reactor; exposing the
composition to a high shear environment; and introducing or
changing over time at least one variable affecting the properties
of the at least one polymer that can be modified to produce a
combinatorial library of materials; wherein the thermally-induced
reaction comprises the elimination of trialkylsilanes from polymer
end or side groups to produce a library of amino end or sidegroup
functional polymers.
17. The method of claim 16, wherein the composition is exposed to a
temperature of about 100.degree. C. to about 180.degree. C. while
it is exposed to a high shear environment.
18. The method of claim 16, further comprising evaluating the
materials of the library.
19. The method of claim 16, wherein the composition when introduced
into the apparatus comprises 90 weight % solids or less.
20. The method of claim 16, wherein the exposed functional group is
capable of undergoing a grafting reaction.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/211,219, filed Aug. 2, 2002, the disclosure
of which is incorporated by reference in its entirety herein.
FIELD OF THE INVENTION
[0002] The present invention relates to a continuous process for
the production of combinatorial libraries of modified
materials.
BACKGROUND INFORMATION
[0003] A combinatorial approach for materials synthesis is aimed at
using rapid synthesis and screening methods to build libraries of
polymeric, inorganic or solid state materials. For example,
advances in reactor technology have empowered chemists and
engineers to rapidly produce large libraries of discrete organic
molecules in the pursuit of new drug discovery, which have led to
the development of a growing branch of research called
combinatorial chemistry. Robotic driven parallel synthesizers
consisting of arrays of small batch type reactors have been
designed for such efforts (e.g., Chemspeed, Endeavor, Neptune,
FlexChem, Reacto-Stations). These reactors synthesize milligram to
gram quantities of materials, which can rapidly be screened or
analyzed by various techniques including gas chromatography, FT-IR,
and UV-Visible spectroscopy.
[0004] The development and use of combinatorial methods to develop
new polymeric materials is a topic of considerable current
interest. A large portion of the current focus of this
material-based research is the synthesis of block, graft, dendritic
and functionalized polymers. For example, the production of
copolymer emulsions at temperatures well below 100.degree. C. in a
batch combinatorial chemistry system capable of evaluating 1,000
polymers/week has recently been demonstrated (see Fairley, P.,
"Symyx Makes `Living` Block Copolymer" Chemical Week 1999, 161, No.
17, 5 May, 1999, p. 13)
[0005] An important consideration in making these arrays is that
batch reactors suffer from poor heat transfer characteristics,
which may have a detrimental effect on the materials produced in
batch arrays. In addition, materials produced in small batch
reactors still need to be scaled to an appropriate level for
application testing and product qualification, requiring some
process development and scale up understanding.
SUMMARY OF THE INVENTION
[0006] There exists a need for a readily scalable, economical
method that can rapidly produce many combinatorial formulations in
quantities appropriate for application development. The present
invention provides a new method of preparing combinatorial
libraries of chemically-modified materials in a high throughput
fashion. It allows for library members to be continuously made and
collected. It also allows the option of later determining the
starting materials for a member by tracing back to the time when
the starting materials would have been input.
[0007] In one aspect the present invention provides a continuous
method of making a combinatorial library of materials comprising
providing a plug flow mixing apparatus having a high shear
environment and devolatilization capabilities, continuously
introducing into the mixing apparatus a composition containing at
least one polymer that can be modified by a thermally-induced
reaction into the reactor, exposing the composition to a high shear
environment, and introducing or changing over time at least one
variable affecting the properties of the at least one polymer that
can be modified to produce a combinatorial library of materials.
The composition may be exposed to a temperature of about
100.degree. C. to about 180.degree. C. while it is exposed to a
high shear environment. The materials of the library may further be
evaluated.
[0008] The composition when introduced into the apparatus comprises
90 weight % solids or less. The composition may comprise at least
one polymer that is temperature sensitive.
[0009] The thermally-induced reaction may remove at least one
protective group to expose a functional group. The exposed
functional group may be capable of undergoing a grafting reaction.
For example, the functional group may ethylenically or
acetylenically unsaturated. An in situ chemical reaction may be
caused to take place at the functional group. A library of graft
polymers may be made.
[0010] The thermally-induced reaction may comprise the elimination
of isobutylene and water from methacrylic and acrylic esters to
produce one or both of acid and anhydride functionalities. This
reaction may be catalyzed, optionally by an acid.
[0011] The thermally-induced reaction may comprise the elimination
of trialkylsilanes from trialkylsiloxy end or side group containing
polymers to produce a library of hydroxyl end or side group
functional polymers. The thermally-induced reaction may comprise
the elimination of trialkylsilanes from trialkylsilazane end or
side group containing polymers to produce a library of amino end or
sidegroup functional polymers.
[0012] The thermally-induced reaction may comprise a
deesterification reaction to produce a library of hydroxyl- or
carboxylic acid-functionalized polymers. This reaction may be
base-catalyzed.
[0013] The thermally-induced reaction may comprise the elimination
of N.sub.2 from acyl azides and subsequent rearrangement to form
isocyanate functionality.
[0014] The thermally-induced reaction may comprise the elimination
of benzenesulfenic acid from poly(vinyl phenyl sulfoxide) to
produce a library of polyacetylene-containing polymers.
[0015] The thermally-induced reaction comprises the elimination of
trialkylsilanes from trialkylsilthiane end or sidegroup containing
polymers to produce a library of thiol end or sidegroup functional
polymers. The thermally-induced reaction may comprise the
elimination of trialkylsilanes from trialkylsilyl-substituted
ethynyl monomers, such as 2-, 3- and
4-[(trimethylsilyl)-ethynyl]styrenes, to produce a library of
ethynyl-containing sidegroup or end functionalized polymers.
[0016] Variable that can be changed when conducting the method
include concentration of starting material, type of starting
material, pressure in the reactor, temperature profile in the
reactor, amount of energy supplied to a reaction zone, type of
energy supplied to a reaction zone, type of component mixing,
degree of component mixing, residence time, type and amount of
grafting agent, and where and when additional components are
introduced into the reactor. Other variables include physical
mixing of components and chemical reaction of components. The
variables may be changed in a continuous manner or a stepwise
manner.
[0017] The mixing apparatus may comprises a high viscosity
devolatilizer, such as a LIST apparatus. The mixing apparatus may
be operated in series with one or more other continuous reactors.
The ability to control feed flows, feed locations, and
compositional variations in a devolatilizing reactor provides an
opportunity to produce a variety of compositions in a continuous,
economical, and scalable fashion. A major advantage of producing a
combinatorial library of materials in a devolatilizing reactor is
that different library components need only be separated in time.
They do not need to be physically separated.
As used herein:
[0018] "actinic radiation" means electromagnetic radiation,
preferably UV and IR;
[0019] "axial mixing" means mixing in a direction parallel to the
overall direction of flow in a reactor;
[0020] "block copolymer" means a polymer having at least two
compositionally discrete segments, e.g., a di-block copolymer, a
tri-block copolymer, a random block copolymer, and a star-branched
block copolymer;
[0021] "combinatorial" means combining two or more components and
incrementally changing one or more variable(s) that can affect the
component(s) or how the components interact;
[0022] "continuous" means generally that reactants enter a reactor
at the same time (and, generally, at the same rate) that polymer
product is exiting the same reactor;
[0023] "devolatilizing kneader" means an apparatus that provides
mixing or kneading action and is capable of operation under vacuum
sufficient to remove volatile by-products;
[0024] "di-block copolymer" or "tri-block copolymer" means a
polymer in which all the neighboring monomer units (except at the
transition point) are of the same identity, e.g., -AB is a di-block
copolymer comprised of an A block and a B block that are
compositionally different, ABA is a tri-block copolymer in which
the A blocks are compositionally the same, but different from the B
block, and ABC is a tri-block copolymer comprised of A, B, and C
blocks, each compositionally different;
[0025] "end-functionalized" means a polymer chain terminated with a
single functional group on one or both chain ends;
[0026] "energy" means actinic radiation, thermal energy, and
electron beam;
[0027] "functional group" means an appended moiety capable of
undergoing a reaction;
[0028] "high shear environment" means mixing conditions in which
physical mixing elements provide shear stress and intense mixing to
blend materials having high melt viscosities;
[0029] "high viscosity devolatilizer" means an apparatus that
provides a high shear mixing environment and a vacuum sufficient to
remove volatile by-products from a material or mixture of
materials;
[0030] "hydrogenated" means fully or partially hydrogenated; i.e.,
hydrogen has been added to all or some double bonds of an
unsaturated molecule;
[0031] "in situ grafting" means a grafting reaction is carried out
on a material that has been functionalized during the same process
run; i.e., the material is not removed from the reactor between the
functionalizing and grafting reactions;
[0032] "living anionic polymerization" means, in general, a chain
polymerization reaction that proceeds via an anionic mechanism
without chain termination or chain transfer. (For a more complete
discussion of this topic, see Anionic Polymerization Principles and
Applications. H. L. Hsieh, R. P. Quirk, Marcel Dekker, NY, N.Y.
1996. Pg 72-127);
[0033] "living end" means a stable radical, cation, or anion
capable of undergoing further polymerization reactions;
[0034] "modify" means perform a reaction to change the chemical
nature of a material or a mixture of materials by physical and/or
chemical reactions;
[0035] "plug" means a theoretical slice of a reaction mixture cut
in a direction perpendicular the overall direction of flow in a
reactor;
[0036] "plug flow reactor (PFR)" means a reactor that ideally
operates without axial mixing (see An Introduction to Chemical
Engineering Kinetics and Reactor Design; Charles G. Hill J. Wiley
and Sons 1977, p. 251);
[0037] "polydispersity" means weight average molecular weight
divided by number average molecular weight; polydispersity is
reported as a polydispersity index (PDI);
[0038] "protected functional group" means a functional unit that is
reactive after the removal of a "protective" group that prevents
reaction at a particular site;
[0039] "radial mixing" means mixing in a direction perpendicular to
the overall direction of flow in a reactor;
[0040] "random block copolymer" means a copolymer having at least
two distinct blocks wherein at least one block comprises a random
arrangement of at least two types of monomer units;
[0041] "reaction zone" means a portion or portions of a reactor or
reactor system where at least one specific interaction of
components occurs such as physical reaction, e.g., mixing, or a
chemical reaction; it may also refer to one or more portion(s) of a
reactor that is independently controllable as to conditions such as
temperature;
[0042] "residence time" means the time necessary for a theoretical
plug of reaction mixture to pass completely through a reactor;
[0043] "star-branched polymer" means a polymer consisting of
several linear chains radiating from junction points (See Anionic
Polymerization Principles and Applications. H. L. Hsieh, R. P.
Quirk, Marcel Dekker, NY, N.Y. 1996. Pg 333-368);
[0044] "star-branched block polymer" or "hyper-branched block
copolymer" means a polymer consisting of several linear block
chains linked together at one end of each chain by a single branch
or junction point, also known as a radial block copolymer (See
Anionic Polymerization Principles and Applications. H. L. Hsieh, R.
P. Quirk, Marcel Dekker, NY, N.Y. 1996. Pg 333-368);
[0045] "temperature profile" means the temperature or temperatures
experienced by a reaction mixture plug over time as it moves
through a reactor (For example, if the temperature is constant
through the reactor, the temperature profile will have a zero
slope; if the temperature increases through the reactor, the
profile will have a positive slope);
[0046] "temperature-sensitive" means a monomer susceptible to
significant side reactions such as degradation, cross-linking, and
chain scission with reactive sites, such as carbonyl groups, on the
same, or different, polymer chain as the reaction temperature
rises; and
[0047] "thermally-induced reaction" means a reaction that is
induced or driven by heat.
[0048] An advantage of at least one embodiment of the present
invention is that a devolatilizing reactor may be operated as a
part of a continuous system. Accordingly, libraries formed with
this system can have members with masses greater than members made
in confined volumes, e.g., to the size of microtitre plates, and
can be made at higher process rates.
[0049] An advantage of at least one embodiment of the present
invention is the ability to scale libraries of compositions from
laboratory scale quantities to production-scale quantities.
[0050] An advantage of at least one embodiment of the present
invention is that multiple reagents can be added along the reactor
length with ease.
[0051] An advantage of at least one embodiment of the present
invention is that the possibility of exposing the reactor system to
potential contaminants is reduced (compared to using a batch
reactor) due to the ability to continuously feed reactants through
stable, enclosed feed systems.
DETAILED DESCRIPTION
[0052] The present invention provides continuous methods of making
a combinatorial library of materials using a devolatilizing
reactor. According to the present invention, at least one of one or
more components introduced into the reactor, or at least one
process variable affecting the component(s), is changed to produce
a combinatorial library of materials.
[0053] The methods of the present invention can be used in
combination with other batch or continuous combinatorial reactor
systems, including temperature-controlled, stirred tubular
reactors, shrouded extruders, static mixers, and pouch-based
systems such as those described in U.S. patent application Ser. No.
09/793,666 and U.S. Ser. No. 09/824,330.
[0054] Materials generally pass through the devolatilizing reactor
in a plug flow manner. In other words, due to the configuration
and/or operation of the reactor, any particular selected plug of
material traversing the reactor has minimal axial mixing with an
adjacent plug of material even though there will be radial mixing
within the plug. This aspect of the reactor allows samples to be
continuously and sequentially made with different starting
materials or under different processing conditions even though the
samples may not be physically separated. Such a system provides
many operating advantages such as the ability to make many samples,
including those obtained under non-steady state conditions, and no
"down time" when materials or operating conditions are changed.
This is because operation does not have to be stopped to change the
composition of, or conditions of making, the individual samples.
Changes can be made while the plug flow reactor is operating.
Samples can be continuously collected as they exit the reactor.
Additionally, one only needs to know the time that particular
starting materials are added (or the time at which another change
took place), the residence time of the material passing through
reactor (typically the flow rate), and the time a particular sample
is collected to be able to collect samples and later determine
their starting materials or the operating conditions they were
subjected to.
[0055] An advantage of the combinatorial approach to materials
synthesis of the present invention includes the ability to vary
components of a material without stopping the reaction process. The
material libraries synthesized may comprise any number of members,
depending on how many factors are varied during the operation of
the reactor.
[0056] A particular sample can be traced from the time it enters
the reaction system to the time it leaves the system, based on the
flow rate of the materials through the system. The time a sample
remains in the system is referred to as its residence time. When
the residence time and the time the raw material enters the reactor
are known, it can be determined when the sample will exit the
system. With this information, the resulting material can be
matched up with the starting materials and with changes in process
conditions or composition additions made as the material flowed
through the reactor. In-line analysis is not required to determine
where different plugs of materials are to be collected. Only
knowledge of the residence time of a particular interaction is
needed to collect distinct plugs after a variable has been changed.
However, reactor systems could be interfaced with on-line detection
capabilities (UV, IR, Raman, Viscometers) if desired. A
combinatorial library of materials generally refers to a group of
related samples of materials wherein each sample is different in
some way from the other samples. The difference may be, e.g., the
type of components, amount of components, or conditions to which
the sample is subjected, such as temperature and pressure. The
ability to rapidly and easily vary a number of aspects of the
reactor system, especially while it is being continuously operated,
can substantially increase the scope and number of different
samples in a library compared to libraries made by conventional
combinatorial methods.
[0057] Unlike typical combinatorial synthesis approaches, the
process of the present invention provides the capability to change
or adjust the process variables as well as the residence time of
each sample. The process of the invention also makes it possible
for instantaneous addition to, or alteration of, individual samples
during the reaction process. For example, additional reactive
components may be added at various points along the reaction
path.
[0058] Changes to the reactor system may be made in a variety of
ways. For example, if the effect of an amount of a particular
component is being studied, the amount added may be varied. The
variation may be done in a linear or stepwise manner. If the type
of component being added is being studied, different types of
components may be sequentially added at the entrance of the
reactor, or at some particular downstream point.
[0059] Operating conditions, such as pressure, or energy exposure
may also be changed for only a particular sample or set of samples.
For example, a section of the reactor, or the entire reactor, may
be cooled while some sample(s) pass through, then the temperature
may be raised for subsequent sample(s). Alternatively, a condition
can be continuously varied and the resulting material continuously
analyzed, even if steady state conditions are not reached.
[0060] The reactor system of the invention will also easily allow
for changing more than one component or operating condition at a
time. In addition, the reactor provides the advantage of being able
to control the size of a particular sample. Sample sizes can range
from, e.g., milligram to multi-kilogram, or whatever amount is
desired. This flexibility can allow for appropriately sized samples
to be made based on the intended screening method.
[0061] Within the reactor, chemical or physical reactions can occur
as a sample passes through a reaction zone. A reaction zone may be
the entire length of the reactor, or may be limited to a particular
section of the reactor. A reaction zone may be used to subject a
sample to at least one of, e.g., heat, cold, UV radiation, e-beam
irradiation, pressure, or vacuum. The duration for which each
sample is subjected to process variables may be controlled by
adjusting the length and/or diameter of the reaction zone(s) or the
rate at which components pass through the reaction zone. The
samples may be collected in separate or adjoining containers and
can be labeled and individually archived for subsequent or further
reaction or analysis.
[0062] Once the sample has been removed from the reaction zone and
the chemical and/or physical reaction has taken place, the sample
can be analyzed using techniques such as IR, far IR, UV, visible or
Raman spectroscopy, refractive index, acoustical measurement,
compression testing, viscometry, light scattering, nuclear magnetic
resonance (NMR), gel permeation chromatography (GPC), differential
scanning calorimetry (DSC), thermogravimetric analysis (TGA),
dynamic mechanical analysis (DMA), x-ray diffraction (XD), and mass
spectral analysis (MS), impedence measurements, ultrasonics, and
the like.
[0063] One aspect of the present invention employs
thermally-induced reactions to modify polymeric materials. Many
types of thermally-induced reactions are suitable for the present
invention. One suitable type of reaction is a rearrangement
reaction in which the substituents or moieties of a molecule are
rearranged to form a new molecule, i.e., the bonding site of a
substituent or moiety moves from one atom to another in the same
molecule. Another suitable type of reaction is an elimination
reaction in which one or more substituents is removed from a
molecule. Specific types of reactions that can be carried out
include, but are not limited to, pyrolysis reactions,
acid-catalyzed reactions, deprotection reactions, condensation
reactions, hydrolysis reactions, imidization reactions,
base-catalyzed reactions, and deesterification, e.g.,
deacetylation. In a pyrolysis reaction, a complex molecule is
broken into simpler units by the use of heat. In an acid-catalyzed
reaction, acid is used to drive or induce the thermal reaction. In
a deprotection reaction, a protecting group is removed to expose a
reactive functional group. In a condensation reaction, two
molecules react to form a new molecule and release a byproduct,
which is typically water. In a hydrolysis reaction, water reacts
with another molecule (e.g., ester) to form one or more new
molecules. In an imidization reaction, anhydrides react with
primary amines via an intermediate amic acid functionality to form
an imide ring and water. In a base-catalyzed reaction, base is used
to drive or induce the thermal reaction. In a deesterification
reaction, an ester is converted into a carboxylic acid or an
anhydride. In a deacetylation reaction, an ester is converted into
an alcohol with removal of an acetyl group. See, for example,
Hawker et al., Macromolecules, 1998, 31, 1024.
[0064] One type of reaction may be followed by a subsequent
reaction. For example, the acid catalyzed desterification or
modification reaction of poly(meth)acrylic esters to form
polymethacrylic acid is followed by a condensation reaction to form
polymethacylic anhydride or a functional group exposed by a
deprotection reaction may then be further reacted, e.g., by
grafting a moiety to the deprotected site.
[0065] Once the initial reaction has occurred, further reactions,
such as hydrolysis, condensation and in situ grafting may be
performed.
Reactor System
[0066] The thermally-induced reactions of the present invention are
carried out in a mixing apparatus that provides a high shear
environment and has devolatilization capabilities. The intensive
mixing provided by a high shear environment continually brings
different portions of the reacting mixture to the surface of the
bulk of mixture material. At the bulk surface, reaction products
are exposed to the vacuum in the apparatus. The vacuum causes the
lower molecular weight products, which are typically undesirable
by-products, to be drawn out of the reacting mixture. Removal of
the by-products causes the kinetics to favor additional reactions.
Accordingly, as the mixture moves through the mixing apparatus, the
desired (higher molecular weight) product is continuously produced,
and remains in the mixture, while undesired (low molecular weight)
by-products are removed from the mixture. The high shear and
devolatilization characteristics of the apparatuses used in the
present invention, which provide a favorable reaction equilibrium,
allow the thermally-induced reactions to be carried out at
temperatures lower than would otherwise be required. The ability to
use lower temperatures provides the added advantage of enabling the
production of molecules that could not be made previously due to
problems with, e.g., thermal degradation and crosslinking.
[0067] In the present invention, reactions are typically carried
out at temperatures of about 100.degree. C. to about 180.degree.
C., but may be carried out over a broader range of temperatures,
e.g., 50 to 250, and is only limited by the availability of
suitable heat transfer fluids. Many reactions that can be carried
out per the present invention normally require higher temperatures,
e.g., 200.degree. C. or higher because the apparatus used do not
provide efficient mixing and heat transfer. The higher temperatures
are needed to ensure that the inner portions of the bulk material
are sufficiently heated to drive the reaction. However, these
higher temperatures can have detrimental effects, such as polymer
degradation, as explained above.
[0068] Even though the high shear environment and devolatilization
characteristics of the apparatus of the present invention allow
reactions to be carried out at temperatures lower than would
otherwise be required, most of the processes are carried out at
above-ambient temperatures. When the polymer and/or the reaction
mixture is processed at above-ambient temperatures, addition of a
thermal stabilizer to the reaction mixture is preferred. A variety
of thermal stabilizers, including hindered phenols and phosphites,
are widely used in the industry. Whichever stabilizer is used, it
is preferably soluble in the reaction mixture and products;
otherwise, a solvent will be necessary as a delivery mechanism.
[0069] The methods of the present invention can be carried out
using batch or continuous processes. Methods of the present
invention are particularly advantageous for use with continuous
systems such as those described in copending U.S. patent
application Ser. No. 09/500,155, having the title "Continuous
Process for the Production of Controlled Architecture Materials,"
because the apparatus of the present invention can be set up in
series with a polymer-producing apparatus so that the starting
polymeric material is fed directly into the mixing apparatus.
[0070] The mixing apparatuses of the present invention are capable
of handling highly viscous polymer melts. For example, they can
process polymer melts having viscosities as high as about 500,000
cps (500 Pascal (Pa) seconds) and solids concentrations of about 1
to about 90 weight %. They can process these high viscosity
materials at residence times of about 10 to about 60 minutes. The
mixing apparatuses also have devolatilization capabilities. The
apparatuses may come standard with vacuum equipment or may be
fitted with vacuum equipment. The apparatuses can maintain a vacuum
of about 1 to about 200 torr (about 133 to about 26600 Pa) under
high viscosity mixing conditions.
[0071] The mixing apparatus are also, preferably,
temperature-controlled. The apparatuses may have one or more
temperature-controlled zones. If the apparatus has more than one
temperature-controlled zone, a temperature gradient can be
maintained through the mixing apparatus. This can be advantageous
in many situations, for example when carrying out an exothermic
reaction, because the need for heat removal can vary throughout the
reactor, depending on the reaction being carried out.
[0072] Apparatuses that are suitable for the present invention
include high viscosity processors and vacuum-fitted high
performance kneaders. These apparatuses provide a high shear
environment, devolatilization capabilities, and, optionally,
temperature-controlled zones.
[0073] A suitable high viscosity processor, which comes standard
with vacuum equipment, is a LIST Discotherm B processor (available
from List AG, Acton, Mass.). The LIST Discotherm B high viscosity
processor (described in more detail in the Examples section) is
ideally suited for use in the present invention. It provides
intensive mixing and kneading in combination with large
heat-transfer surfaces and long residence times thereby enabling
the reaction and the removal of by-products to take place with
great ease. The heat transfer surfaces are continuously swept by
kneading elements, which increases thermal efficiency and ensures
high heat transfer rates. The LIST's inner cavity also provides a
large working volume (i.e., volume occupied by the reaction
mixture) and fill level, thus allowing for high throughput and long
retention times. Also, the working volume occupies only about 60%
of the total volume of the reactor, which provides ample room to
allow for disengagement and flashing of off-gases and vapors as
they are brought to the bulk surface by the intensive mixing.
[0074] Suitable kneaders, fitted with a vacuum system, include an
MKD 0,6-H 60 IKA kneader (described in more detail in the Examples
section), Buss kneaders (available from Coperion Buss AG, Pratteln,
Switzerland), and Srugo Sigma kneaders (available from Srugo
Machines Engineering, Netivot, Israel). The kneaders are fitted
with vacuum equipment by attaching a vacuum pump to vacuum ports on
the kneader.
Process Variables
[0075] The production of desired modified polymers can be obtained
by controlling various process variables. Process variables can
influence, for example, the speed at which, and extent to which, a
reaction takes place, and ratio of functional groups produced.
Variables that can be changed when conducting the method include:
concentration or composition of starting material, type of starting
material, pressure (i.e., vacuum) in the mixing apparatus,
temperature and/or temperature profile in the reactor, type and
amount of component or grafting agent added, degree of mixing,
residence time, and where and when additional components are
introduced into the high viscosity reactor. For example, the level
of deprotection can be increased by increasing the temperatures
and/or increasing the vacuum levels to affectively remove
byproducts. If less deprotection, modification or elimination is
desired the vacuum level can be lessened or the temperature can be
lowered.
[0076] The variables may be changed in a continuous manner or a
stepwise manner. The ability to control feed flows, feed locations,
and compositional variations in a high viscosity reactor provides
an opportunity to produce a variety of compositions in a
continuous, economical, and scalable fashion.
Starting Polymer Systems
[0077] Suitable starting polymeric materials include controlled
architecture materials (CAM), which are polymers of varying
topology (linear, branched, star, star-branched, combination
network), composition (di-, tri-, and multi-block copolymer, random
block copolymer, random copolymers, homopolymer, graft copolymer,
tapered or gradient copolymer, star-branched homo-, random, and
block copolymers), and/or functionality (end, site specific,
telechelic, multifunctional, macromonomers).
[0078] The invention allows the modification polymers synthesized
by step growth polymerizations, specifically tradition or
living/controlled free radical, group transfer, cationic or living
anionic polymerizations. Suitable starting polymers include the
fluorinated materials described in co-pending patent application
U.S. Ser. No. 10/211,096, incorporated by reference. Of most
industrially relevant are tradition or living/controlled free
radical and living anionic polymerizations.
[0079] The starting polymeric materials may be made by any method
known in the art. For example, the may be made by the method
described in copending U.S. patent application Ser. No.
09/500,155.
[0080] The starting polymer systems may be synthesized in processes
that are carried out in batch, semibatch, continuous stirred tank
reactor (CSTR), tubular reactors, stirred tubular reactors, plug
flow reactors (PFR), temperature controlled stirred tubular
reactors as described in WO 0158962 A1 and co-pending U.S. patent
application Ser. No. 09/824,330, static mixers, continuous loop
reactor, extruders, shrouded extruders as described in WO 9740929,
and pouched reactors as described in WO 9607522 and WO 9607674. The
media in which the polymerizations may take place are bulk,
solution, suspension, emulsion, ionic liquids or supercritical
fluids, such as supercritical carbon dioxide.
[0081] Specific methods of making the starting polymer systems
include atom transfer radical polymerization (ATRP), reversible
addition-fragmentation chain transfer polymerization (RAFT), and
nitroxyl or nitroxide (Stable Free Radical (SFR) or persistant
radical)-mediated polymerizations. These controlled processes all
operate by use of a dynamic equilibrium between growing radical
species and various dormant species (see Controlled/Living Radical
Polymerization, Ed. K. Matyjaszewski, ACS Symposium Series 768,
2000).
[0082] Suitable starting materials include those with a terminal
unsaturated carbon-carbon bond, such as anionically-polymerizable
monomers (see Hsieh et al., Anionic Polymerization: Principles and
Practical Applications, Ch. 5, and 23 (Marcel Dekker, New York,
1996) and free radically-polymerizable monomers (Odian, Principles
of Polymerization, 3.sup.rd Ed., Ch. 3 (Wiley-Interscience, New
York, 1991)).
[0083] At least one aspect of this invention provides utility in
particular for temperature-sensitive monomers. Examples of
temperature sensitive monomers include styrenes, dienes,
(meth)acrylates, and mixtures thereof, as well as polymeric systems
that degrade at elevated temperatures over long periods of
time.
[0084] Other suitable monomers include those that have multiple
reaction sites. For example some monomers may have at least two
anionically-polymerizable sites. This type of monomer will produce
branched polymers. This type of monomer preferably comprises less
than 10 molar percent of a given reaction mixture because larger
amounts tend to lead to a high degree of crosslinking in addition
to branching. Another suitable monomer is one that has at least one
functionality that is not anionically-polymerizable in addition to
at least one anionically polymerizable site.
[0085] Polyolefin-based CAM's are also suitable materials for the
modification reactions of the present invention. These polyolefin
CAM's may be made by hydrogenation of polydiene systems.
Particularly useful are hydrogenated poly(butadiene), polyisoprene
poly(1,3-pentadiene), and poly(1,3-cyclohexadiene), which can be
synthesized via "living" anionic polymerization. Hydrogenation of
such polydienes produces various polyolefins, the nature of which
is controlled by the polymer backbone microstructure. For example
hydrogenation of poly(1,4-butadiene) produces a polyethylene-like
structure, while hydrogenation of poly(1,2-butadiene) produces a
polyethylethylene (ie. polybutylene) structure.
[0086] This ability to hydrogenate and subsequently modify
polyolefin-based CAM's can be used to produce dispersants,
compatibilizers, tie layers, and surface modifiers that are unique,
polyolefin-miscible, and industrially-useful.
[0087] Hydrogenation of polymer blocks can be performed by various
routes including homogeneous diimide reduction as described by Hahn
in J. Polym. Sci: Polym Chem. 1992, 30, 397, and by heterogeneous
Pd catalyzed reduction as described by Graessley J. Polym. Sci;
Polym Phys. Ed. 1979, 17, 1211. The diimide reduction involves the
use of organic reducing agents such as p-toluenesulfonhydrazide in
the presence of a trialkyl amine (e.g., tripropyl amine) and xylene
as a solvent at temperatures of 140.degree. C.
[0088] Fluorinated materials, such as fluorinated (meth)acrylates,
are also suitable for use in the present invention. Fluorinated
monomer units may comprise co-monomers in the materials of the
present invention. The fluorinated materials may comprise, for
example, a backbone mer unit having the following Formula I
##STR1##
[0089] where represents a bond in a polymerizable or polymer chain;
R.sub.f is --C.sub.6F.sub.13, --C.sub.4F.sub.9, or
--C.sub.3F.sub.7; R and R.sub.2 are each independently hydrogen or
alkyl of 1 to 20 carbon atoms; n is an integer from 2 to 11; and x
is an integer of at least 1. The fluorinated materials may be
end-functionalized at one or both terminus with reactive end
groups. If there are two reactive end groups, they may be the same
or different. Fluorinated diene, methacrylate and styrenic homo and
block copolymers end-functionalized with alcohol(s), thiol(s),
and/or amine(s) may be synthesized anionically by the use of
suitable anionic initiators which contain protected functional
groups that can be removed by post polymerization techniques.
Suitable functional initiators are known in the art and are
described in, e.g., U.S. Pat. No. 6,197,891, U.S. Pat. No.
6,160,054, U.S. Pat. No. 6,221,991, and U.S. Pat. No.
6,184,338.
[0090] The fluorinated materials may be made by the same living
anionic polymerization methods previously described. A more
detailed description of some suitable fluorinated materials is in
co-pending patent application U.S. Ser. No. 10/211,096.
Thermally-Induced Reactions
[0091] As previously stated, a variety of thermally-induced
reactions may be carried out on starting materials using the
processes of the present invention. This section provides
non-limiting examples of reactions that can be carried out.
[0092] One suitable reaction is the rearrangement of an acyl azide
to provide an isocyanate group (i.e., a Curtius rearrangement) as
shown in Formula I ##STR2##
[0093] In this reaction N.sub.2 is eliminated and a nitrogen atom
replaces the carbon atom that is attached to the polymer backbone
to form an isocyanate functionality.
[0094] Various reactions may be carried out to produce
acetylene-containing polymers. In these reactions, a sulfoxide is
pyrolyzed to give the polyactylene and a sulfenic acid byproduct
(RSOH) as shown in Formula II. For example, a benzenesulfenic acid
may be eliminated from poly(phenyl vinyl sulfoxide)-containing
copolymers to produce polyacetylene-containing copolymers, such as
poly(styrene-acetylene) block copolymers. Polyacetylene is
typically difficult to work with because it is very insoluble in
other materials. However, including it in a block structure allows
the final structure to remain soluble.
[0095] Vinyl sulfoxides having the general structure
CH.sub.2.dbd.CH--SOR are suitable for polymerization. Applicable R
groups include primary alkyl, aryl, and alkylaryl-amines, for
example, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl
group having 5 to 12 carbon atoms, an aralkyl group having 7 to 22
carbon atoms or an aryl group having 6 to 12 carbon atoms.
##STR3##
[0096] In other suitable reactions, polymeric materials containing
methacrylic and acrylic esters can be modified, e.g.,
functionalized or deesterified, by treatment with catalytic amounts
of acid at above-ambient temperatures. The treatment with acid at
above-ambient temperature causes ester alkyl-oxygen cleavage,
resulting in the release of relatively volatile aliphatic reaction
products to form (meth)acrylic acid functionalized polymers,
followed by (in some cases) the release of water via a condensation
reaction to form (meth)acrylic anhydride functionalized polymers as
shown in Formula III. This method can be applied to a vast array of
polymeric reagents to produce acid and anhydride functionality.
##STR4##
[0097] Appropriate (meth)acrylic ester-containing polymers include
homopolymers, block copolymers, random copolymers, graft
copolymers, starbranched and hyperbranched polymers. Specific
examples include, but are not limited to, polymers containing
t-butyl methacrylate, t-butyl crotonate, t-butyl acrylate, t-pentyl
acrylate, 1,1-dimethylethyl-.alpha.-propylacrylate,
1-methyl-1-ethylpropyl-.alpha.-butylacrylate,
1,1-dimethylbutyl-.alpha.-phenylacrylate, t-hexyl acrylate, t-octyl
methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, and
t-pentyl methacrylate. The preferred systems include t-butyl
acrylate and t-butyl methacrylate.
[0098] The reaction may also be carried out on block copolymers
containing methacrylic or acrylic block segments. Block copolymers
containing poly(methacrylic acid) (PMAA), poly(acrylic acid) (PAA),
poly(methacrylic anhydride) and poly(acrylic anhydride) block
segments are typically difficult to introduce into a polymeric
material, particularly in block copolymer systems synthesized by
anionic routes, due to the inability of methacrylic/acrylic acid or
methacrylic/acrylic anhydride to participate in anionic
polymerizations. The present invention makes it easier to introduce
these groups because they are in a protected form, which is
amenable to conventional living polymerization techniques. These
protecting groups are readily removed using the procedures
described in this invention, resulting in a useful strategy to
introduce these reactive functional groups into a polymeric
backbone.
[0099] Polymeric materials containing t-butyl methacrylate groups
are attractive reagents for this acid-catalyzed pyrolysis reaction
because the t-butyl groups can be easily removed to produce
methacrylic acid (PMAA) and methacrylic anhydride (PMAn) moieties,
which may impart water solubility or provide reactive functionality
to polymer systems.
[0100] Suitable acids for the above modification or
deesterification include the aromatic sulfonic acids,
methanesulfonic, ethanesulfonic, 2-propanesulfonic,
benzenesulfonic, trifluoromethanesulfonic, and preferably,
toluenesulfonic acid.
[0101] In addition to the catalytic acid modification, the
methacrylate ester functionality may also be modified by the use of
an alkali metal superperoxide such as potassium superperoxide in a
suitable solvent such as a mixture of dimethyl sulfoxide and
tetrahydrofuran. This technique has been taught for example by R.
D. Allen, et al., Coulombic Interactions in Macromolecular Systems,
A.C.S. Symposium Series, #302, pg. 79-92 (1986). The resulting
modified product may be acidified with small amounts of an acid
such as hydrogen chloride to improve solubility. Due to the
difficulty in handling such reagents, the latter method is not
preferred for commercial use.
[0102] In processes other than those of the present invention,
typically, t-butyl methacrylate segments undergo thermally induced
deesterification, under solventless conditions at temperatures
above 200.degree. C., or in solution, in the presence of trace acid
for extended periods (8-12 hr) at 110.degree. C. These known
processes have several drawbacks such as: (1) in the bulk state,
anhydride formation is hampered by the inefficient removal of
by-products such as water, which can be trapped due to hydrogen
bonding with the newly formed methacrylic acid segments; and (2)
solution deesterification of (meth)acrylate materials often
requires long reaction times, rendering any industrial solution
process costly.
[0103] At least one aspect of the present invention overcomes these
drawbacks because it allows for a lower temperature solvent-free
reaction and it provides superior mixing and vacuum control, which
help to drive the above equilibrium reaction to form materials with
high anhydride levels.
[0104] In another aspect of this invention, polymeric materials
containing styrenic-ester monomers can be modified by treatment
with a base at above-ambient temperatures. Strong bases are known
in the art. See, for example, Hawker et al., Macromolecules, 1998,
31, 1024. Examples include potassium t-butoxide and sodium
t-butoxide and other alkyl metal oxide bases, amines, metal alkyls
known in the art. In reactions of this sort, a molar equivalent of
base is added to the reactor. Adding as little as 1/2 to 1 weight %
of base will induce the desired reaction. The treatment with base
at above-ambient temperature results in cleavage and the release of
relatively volatile aliphatic reaction products and the formation
of the desired hydroxyl functionalized polymers. For example the
deesterification of esters produces hydroxyl functionalized
species, e.g., the deesterification of poly(4-acetoxystyrene)
yields poly(4-hydroxystyrene). Deesterification of esters can also
lead to carboxylic functionalities, e.g., a poly(alkylbenzoate
ester) can yield a poly(alkylbenzoic acid). Formula IV shows a
base-catalyzed deesterification. ##STR5##
IV
[0105] For Formula IV, appropriate starting polymers include those
that contain, for example, para-, meta-, or ortho-acetoxystyrene. R
may be any alkyl ester or aryl ester, preferably a primary alkyl
ester.
[0106] Aspects of the present invention are also suitable to carry
out deprotection reactions. Polymeric systems containing latent or
protected functional groups can be synthesized, for example, in an
extruder or stirred tube reactor, or by other known methods. The
protecting groups are added to prevent the functional groups from
reacting until the desired stage of a reaction process. The
functional groups can be side groups or end groups. They can be,
e.g., ethylenically or acetylenically unsaturated. After being
incorporated into a polymer, these protected functional groups can
undergo deprotection, to expose or produce functionalities at
desired locations in the polymeric material. The functional groups
will be in various locations in the backbone if included in a
random polymer; will be in segments of the backbone if included in
a block copolymer; and will be at the terminus of a polymer chain
if included as a capping agent. An in situ formation of a block
copolymer consisting of reaction of functionalized polymers and
another polymer bearing acceptable terminal groups is also possible
during reactive blending. Reaction of amines with anhydrides
exhibit sufficiently fast kinetics in the melt state to provide
technologically useful, compatibilized polymer blends.
[0107] Diene, methacrylate and styrenic homo and block copolymers
end-functionalized with alcohol(s), thiol(s), and/or amine(s) may
be synthesized anionically by the use of suitable anionic
initiators which contain protected functional groups that can be
removed by post polymerization techniques. Suitable functional
initiators are known in the art and are described in, e.g., U.S.
Pat. No. 6,197,891, U.S. Pat. No. 6,160,054, U.S. Pat. No.
6,221,991, and U.S. Pat. No. 6,184,338.
[0108] End-functionalized materials can also be synthesized by
adding reagents that contain reactive halogen or unsaturated groups
capable of quenching a "living" anionic polymerization as described
above. Anionic polymerizations are not readily amenable to the
polymerization of monomers containing relatively acidic,
proton-donating groups such as amino, hydroxyl, thiol, carboxyl or
acetylene functional groups. However, these groups can be included
in the polymer via incorporation in functional quenching agents,
i.e., a reactive moiety containing a protected functional group
capable of quenching or terminating an anionically produced polymer
chain, if protected by suitable protecting groups that are stable
at the conditions of anionic polymerization and can be readily
removed by post polymerization treatments. Suitable functional
quenching agents include 1,3-bis(trimethylsilyl)carbodiimmide, and
1-(3-bromopropyl)-2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopentane.
[0109] Block copolymers containing hydroxyl, amino, or thiol
functionalities are difficult to introduce into a polymeric
material, particularly in systems synthesized by anionic routes,
due to the inability of compounds such as hydroxyethyl
methacrylate, 4 vinylphenylethyl amines, or 4-vinylphenyl thiol to
participate in anionic polymerizations. A popular route to these
block copolymers involves the polymerization of (meth)acrylic- or
styrenic-based monomers having protected functional groups. After
polymerization, a deprotection reaction is carried out to produce
hydroxyl, amine, and thiol functionalities. This method is an
attractive approach to imparting water solubility or providing
reactive functionality to polymer systems.
[0110] Tert-alkyl-protected groups can also be removed by reaction
of the polymer with para-toluenesulfonic acid, trifluoroacetic
acid, or trimethylsilyliodide to produce alcohol, amino, or thiol
functionalities. Additional methods of deprotection of the
tert-alkyl protecting groups can be found in T. W. Greene and P. G.
M. Wuts, Protective Groups in Organic Synthesis, Second Edition,
Wiley, New York, 1991, page 41. Tert-butyldimethylsilyl protecting
groups can be removed by treatment of the polymer with acid, such
as hydrochloric acid, acetic acid, para-toluenesulfonic acid.
Alternatively, a source of fluoride ions, for instance
tetra-n-butylammonium fluoride, potassium fluoride and 18-crown-6,
or pyridine-hydrofluoric acid complex, can be employed for
deprotection of the tert-butyldimethylsilyl protecting groups.
Additional methods of deprotection of the tert-butyldimethylsilyl
protecting groups can be found in T. W. Greene and P. G. M. Wuts,
Protective Groups in Organic Synthesis, Second Edition, Wiley, New
York, 1991, pages 80-83.
[0111] A number of trialkylsilane deprotection reactions are also
suitable for the present invention. These reactions include acid
and fluoride anion deprotection reactions that remove the
protecting trialkylsilane groups from terminal- or
side-chain-functionalized polymers, such as trialkylsilthiane end-
or side-group containing polymers. For example, trialkylsilanes can
then be removed by treatment of the polymer with acid, such as
hydrochloric acid, acetic acid, para-toluenesulfonic acid.
Alternatively, a source of fluoride ions, for instance
tetra-n-butylammonium fluoride, potassium fluoride and 18-crown-6,
or pyridine-hydrofluoric acid complex, can be employed for
deprotection. Hydroxyl end- or side-group functionalized polymers,
such as that shown in Formula V, can be readily accessed by anionic
polymerization of styrene derivatives such as
4-(t-butyldimethylsilyloxy)styrene, 5- or 4-vinyl-1,3-benzodioxoles
and 4-vinylphenyl ethanol protected with t-butyldimethylsilyl or
trimethylsilyl groups. Methacrylic hydroxyl-containing species can
be accessed by polymerization of 2-hydroxyethyl methacrylate
protected with a trimethylsilyl group or 2,3-dihydroxypropyl
methacrylate masked with a dioxolane ring. The trimethylsilyl group
or dioxolane ring can then be removed. ##STR6##
[0112] Thiol end- or side-group functionalized polymers can be
obtained by the polymerization of 4-vinylphenyl thiol and
4-vinylphenylethyl thiol protected with a t-butyldimethylsilyl
group. The t-butyldimethylsilyl group can then be removed.
[0113] Amino end- or side-group functionalized polymers can be
obtained by the polymerization of styrenic monomers derived from
4-vinylphenyl, 4-vinylphenylmethyl, and 4-vinylphenylethyl amines
protected with two trimethylsilyl groups. The trimethylsilyl groups
can then be removed.
[0114] Formyl (aldehyde) end- or side-group functionalized polymers
can be obtained by polymerizing styrenic systems derived from
dioxolane-functionalized benzaldehyde, and
N-[(4-vinylphenyl)methylene]-cyclohexamine. 3,4-Acyl substituted
styrenes can be incorporated by silyl enol ether routes such as the
t-butyldimethylsilyl protected enol ethers of vinylacetophenones.
The t-butyldimethylsilyl groups can then be removed.
[0115] Carboxy end- or side-group functionalized polymers can be
obtained by polymerizing 4-vinyl benzoic acid, protected with
oxazoline, ester, or amido functionalities such as in
N-(4-vinylbenzoyl)-N'methylpiperazine and t-butyl 4-vinylbenzoate.
Methacrylate based trimethylsilyl methacrylate can also be
employed. The oxazoline, ester, or amido functionalities can then
be removed by treatment with acid.
[0116] Ethynyl (acetylene) side-group or end-functionalized
polymers can be obtained. For example, ethynyl can be introduced as
part of a polymer's side chain structure through anionic
polymerization of 2-, 3- and 4-[(trimethylsilyl)-ethynyl]styrenes.
The trimethylsilane group(s) can then be removed.
Grafting
[0117] After materials have been deprotected such that a functional
group is exposed, subsequent reactions can be carried out
immediately in the apparatus of the invention. These subsequent
reactions can include grafting substituents onto the polymer
backbone. Various grafting reactions may be carried out. Typically,
these reactions could happen at room temp but occur faster at
higher temperatures.
[0118] The polymeric materials produced by acid-catalyzed pyrolysis
of methacrylic and acrylic esters are methacrylic/acrylic acid or
methacrylic/acrylic anhydride functionalized polymers. These acid-
and anhydride-functionalized polymers may participate in further
grafting reactions including esterification, amidation, and
imidization reactions.
[0119] In the case of esterification, the acid- or
anhydride-functionalized polymeric material is subjected to
reaction with small molecule nucleophiles, most preferably
alcohols. Suitable alcohols that participate in this reaction
consist of, but are not limited to C.sub.1, to C.sub.20, that can
contain one or a combination of alkyl, alkenyl, or alkynyl
moieties, and which can be straight, branched, or cyclic, or a
combination thereof. A lower aliphatic group is typically from
C.sub.1 to C.sub.5. The term alkyl, as used herein, unless
otherwise specified, refers to a saturated straight, branched, or
cyclic, primary, secondary, or tertiary hydrocarbon, preferably of
C.sub.1 to C.sub.20. Mixtures of the foregoing aliphatic alcohols
may also be employed. The preferred aryloxy groups (substituted or
unsubstituted) may be derived from aromatic alcohols including
among others phenol; alkylphenols such as cresols, xylenols, p-,
o-, and m-ethyl and propyl phenols and the like;
halogen-substituted phenols such as p-, o-, and m-chloro and bromo
phenols and di- or tri-halogen substituted phenols and the like;
and alkoxy-substituted phenols such as 4-methoxyphenol,
4-(n-butoxy)phenol and the like. Mixtures of the foregoing aromatic
alcohols may also be employed.
[0120] In the case of amidation or imidization, the acid- or
anhydride-functionalized polymeric material is subjected to
reaction with amine nucleophiles. Suitable amines that participate
in this reaction consist of, but are not limited to, typically
primary alkyl, aryl, and alkylaryl-amines. The primary amines
formula is RNH.sub.2 wherein R stands for an alkyl group having 1
to 10 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms,
an aralkyl group having 7 to 22 carbon atoms or an aryl group
having 6 to 12 carbon atoms.
[0121] In addition to small molecule nucleophiles, polymeric
nucleophiles can be used to add functionality to polymer systems
via grafting reactions. For example, hydroxyl-terminated
poly(lactide), poly(caprolactone), poly(dimethylsiloxane), and
polyethylene glycol can be synthesized by employing a protected
alcohol as part of the catalyst system, as known in the art. Amine
terminated poly(lactide), poly(caprolactone),
poly(dimethylsiloxane), polyethylene glycol, can be synthesized by
employing a protected alcohol as part of the catalyst system, as
known in the art. Amine and alcohol terminated polymers can be
purchased from Aldrich (Milwaukee, Wis.), Tomah (Tomah, Wis.),
Shearwater Polymers (Huntsville, Ala.), and Gelest (Morrisville,
Pa.).
[0122] Diene, methacrylate and styrenic homo and block copolymers
end-functionalized with alcohol(s), thiol(s), and/or amine(s) may
be synthesized anionically by the use of suitable anionic
initiators, which contain protected functional groups that can be
removed by post polymerization techniques. Suitable anionic
initiators are known in the art and are described in, e.g., U.S.
Pat. No. 6,197,891, U.S. Pat. No. 6,160,054, U.S. Pat. No.
6,221,991, and U.S. Pat. No. 6,184,338. Objects and advantages of
this invention are further illustrated by the following examples.
The particular materials and amounts thereof, as well as other
conditions and details, recited in these examples should not be
used to unduly limit this invention.
EXAMPLES
[0123] Time 0 in the Tables indicates the time at which the first
sample was taken.
Test Methods
Infared Spectroscopy
[0124] Samples were run by two methods: either by slicing small
slivers of the sample with a scalpel and examining them on an
IR.mu.S Spectra-Tech Fourier Transform Infrared Microscope
(available from Thermo Spectra-Tech, Shelton, Conn.) used in
transmission mode or as small slivers melt smeared onto CsBr or KBr
crystals and run by transmission on a Bomem MB-100 Fourier
Transform Infrared Spectrometer (available from ABB Bomen, Quebec
City, Canada).
NMR Spectroscopy
[0125] The concentration of each block and confirmation of
elimination or rearrangement was determined by Nuclear Magnetic
Resonance (NMR) spectroscopy analysis. A sample was dissolved in
deuterated chloroform to a concentration of about 10 wt % and
placed in a Unity 500 MHz NMR Spectrometer available from Varian,
Palo Alto, Calif. Block concentrations were calculated from
relative areas of characteristic block component spectra. All
spectra were with H.sup.1 NMR unless otherwise indicated.
Diffusion Ordered Spectroscopy
[0126] Diffusion experiments are currently run on a Varian INOVA
500 MHz NMR spectrometer using a NALORAC 5 mm dual broadband
gradient probe. The samples were submitted for diffusion analysis
via DOSY (diffusion ordered spectroscopy) to determine if
copolymerization and/or hydrolysis of t-butyl groups has occurred.
A DOSY Bipolar Pulse Pair Stimulated Echo pulse sequence was used
in this experiment, to permit separation of NMR signals in a
mixture based on the diffusion coefficients. The gradient was
applied to the sample for 50 msec before acquisition of the
spectrum. TABLE-US-00001 Materials Used Materials Description
Toluene Available from Worum Chemical, St. Paul, Minnesota. IRGANOX
1076 Octadecyl 3,5-di-tert-butyl-4 hydroxyhydrocinnamate available
from Ciba Specialty Chemicals Corp. Tarrytown, New York.
p-Toluenesulfonic acid Available from Aldrich Chemical Co.,
monohydrate Milwaukee, Wisconsin. THF Tetrahydrofuran, available
from ISP Technologies, Wayne, New York. Butylamine Available from
Aldrich Chemical Co. Ethanolamine Available from Aldrich Chemical
Co. Cyclohexylamine Available from Aldrich Chemical Co. Cyclohexane
Available from Worum Chemical. Isoprene Available from Aldrich
Chemical Co. Styrene Available from Ashland Chemical, Columbus,
Ohio. t-Butyl methacrylate Available from Sans Esters Corp., New
York, New York. Diphenylethylene Available from Acros/Fisher
Scientific, Itasca, Illinois. sec-Butyl lithium An anionic
initiator, 1.3 Molar in cyclohexane, available from Aldrich
Chemical Co.
Continuous Vacuum Reactor
[0127] Continuous synthesis reactions were performed in a high
viscosity devolatilizer reactor (LIST Discotherm B6 High Viscosity
Processor, available from List AG, Acton, Mass.). The reactor
consisted of a horizontal, cylindrical housing, comprising 3 zones.
Located in the center of the housing was a concentric main screw
agitator shaft. Mounted on the shaft (and extending perpendicular
to the shaft) were disk elements that had angled peripheral
mixing-kneading bars (extending generally parallel to the shaft).
Stationary hook-shaped bars mounted on the inside of the housing
interacted with and cleaned the shaft and disk elements as they
rotated. The arrangement of the disk elements and mixing-kneading
bars in concert with the stationary hook-shaped bars imparted a
substantially forward plug-flow movement to the material with
minimal axial intermixing. [The plug flow nature of the reactor was
quantified by using a dough-like product injected with a tracer to
obtain a residence time distribution curve. The curve was plotted
against a theoretical curve for 14 ideal continuous stirred tank
reactors in series. The data fit the theoretical curve well,
indicating plug-flow behavior.] Material was discharged from the
LIST by a twin-screw discharge screw.
[0128] The total volume in the reactor was 17.5 L, with a working
volume of 12 L. The housing, shaft, and disk elements were all
heated via a hot oil heating system. The heat transfer area in the
reactor was 0.67 m.sup.2. Temperature was controlled and monitored
in three locations within the reactor: (1) the reactor entrance
zone (temperature T1), (2) the reactor intermediate zone
(temperature T2) and (3) the reactor exit zone (temperature T3). A
variable speed motor drove the agitator shaft at speeds of 5 to 70
rpm and a maximum torque of 885 ft lbs (1200 Nm). A vacuum pump was
attached to the reactor for vapor removal. The condensate was
collected in two evacuated, high vacuum glass solvent traps, which
were submersed in a slurry bath consisting of a suitable coolant,
typically Isopar.TM. ((isoparaffin hydrocarbons C.sub.18-25)
available from Exxon Company USA, Houston, Tex.) and dry ice
(CO.sub.2).
Example 1
Continuous Synthesis of poly(styrene-methacrylic acid/anhydride)
via the p-toluenesulfonic Acid Catalyzed Hydrolysis of
poly(styrene-t-butyl methacrylate) (PS-t-BMA)
[0129] This example illustrates, among other things, (1)
continuously producing a library of materials (2) combining this
invention with other continuous reactor technology, e.g., a
temperature-controlled, stirred tubular reactor, and (3) achieving
the lower temperatures required for the deesterification reaction
in the LIST.
[0130] The starting material was a solution of PS-t-BMA in toluene,
made in a stirred tubular reactor (STR) according to WO0158962,
"Continuous Process for the Production of Controlled Architecture
Materials", Example 6, at a solids concentration of about 37 wt %.
The block copolymer composition was varied in both number average
molecular weight and polydispersity index as a function of time as
shown in Table 1. A solution of p-toluenesulfonic acid monohydrate
in toluene was prepared by mixing 463 g of p-toluenesulfonic acid
monohydrate in 4169 g toluene. The p-toluenesulfonic acid
monohydrate solution was pumped via peristaltic pump at a rate of
9.6 g/min into the last zone of the STR and mixed with the PS-t-BMA
solution in a ratio of 0.0083 to 1. TABLE-US-00002 TABLE 1 Time
Styrene t-BMA Example (min) mole % mole % M.sub.n .times. 10.sup.4
PDI 1A 0 92.8 7.2 2.59 2.43 1B 13 80.3 19.7 3.26 2.48 1C 30 76.7
23.3 3.12 2.68
[0131] The resultant solution was pumped (via a zenith pump at 19.7
rpm) from the STR to the first zone of the continuous vacuum
reactor. The main screw of the vacuum reactor was kept constant at
approximately 34 rpm, while the discharge screw of the vacuum
reactor was maintained at 47 rpm. The vacuum reactor was maintained
at a vacuum of about 2.7 kPa (20 torr) and at temperatures of T1 at
about 123.degree. C., T2 at about 174.degree. C. and T3 at about
174.degree. C.
[0132] The resulting material was tested with Infrared Spectroscopy
and NMR Spectroscopy. Results of the Infrared Spectroscopy
confirmed the presence of anhydride groups (1760 cm.sup.-1) in all
of the samples. Quantitative results illustrated in Table 2 showed
a comparison of the area under an Infrared Spectroscopy spectra
band at 1760 cm.sup.-1 (from the anhydride) to the area under a
spectra band at 1601 cm.sup.-1 (an aromatic ring absorption), which
was assumed to be constant. TABLE-US-00003 TABLE 2 Time PS Pt-BMA
Area Area Ratio of Areas Example (min) mole % mole % M.sub.n
.times. 10.sup.4 PDI 1601 cm.sup.-1 1760 cm.sup.-1 1760/1601
cm.sup.-1 1D 0 95.9 4.1 2.29 2.21 0.65 0.65 1 1E 30 97.8 2.2 2.28
2.18 0.54 0.59 1.09 1F 65 98.7 1.3 2.37 2.13 1.02 1.24 1.22 1G 105
99.2 0.8 2.51 2.13 1.48 1.6 1.08 1H 150 99.1 0.9 2.45 2.21 0.65
0.79 1.22
Results of NMR Spectroscopy revealed the significant decrease in
number of t-butyl groups, consistent with deesterification.
Example 2
Continuous Synthesis of poly(isoprene-methacrylic acid/anhydride)
via the p-toluenesulfonic Acid Catalyzed Hydrolysis of
poly(isoprene-t-butyl methacrylate) (PI-t-BMA)
[0133] This example illustrates (1) synthesis using temperature
sensitive materials, such as polyisoprene-based copolymers that are
susceptible to crosslinking at elevated temperatures and (2)
producing libraries of materials with differing acid to anhydride
ratio through variation of temperature.
[0134] Example 2 was made in a manner similar to Example 1 except
different materials were used and some conditions were changed. A
reactant, p-toluenesulfonic acid monohydrate (76 g), was added to a
solution of (PI-t-BMA) in toluene (19 kg at solids of 40 wt %) in a
wt ratio of reactant to solution of 1:100. The mixture was agitated
with an air-powered stirrer operated at 100 rpm at room temperature
for 20 minutes. The resultant solution was pumped (via a zenith
pump at 19.7 rpm) to the first zone of the continuous vacuum
reactor. The temperature settings in the vacuum reactor were varied
to explore the effect of temperature on extent of deesterification
and crosslinking. Table 3 shows the temperature settings and vacuum
readings.
[0135] Samples were tested continuously with Infrared Spectroscopy.
The continuous process was stopped once crosslinking was observed.
The continuous run was started again after temperatures decreased
to a range where crosslinking would not be evident.
[0136] Results of Infrared Spectroscopy revealed the presence of
characteristic bands at 1801 and 1758 cm.sup.-1 associated with an
anhydride, at 1709 cm.sup.-1 associated with an acid functionality
and at 1736 cm.sup.-1 associated with an ester carbonyl as in a
methacrylate moiety. The ratio of the anhydride to the acid and the
ratio of the ester to acid was calculated from areas under various
bands of the infrared spectra. The ratios, which are given in Table
3, show that, under different temperatures, different ratios are
obtained for the same polymer. TABLE-US-00004 TABLE 3 Time T1 T2 T3
Vacuum Ratio of Ratio of Example (min) .degree. C. .degree. C.
.degree. C. kPa (Torr) Anhydride:Acid Ester:Acid 2A 0 91 100 103
19.2 (144) 0.08 0.73 2B 10 91 100 110 19.2 (144) 0.10 0.72 2C 25 99
110 116 18.0 (135) 0.16 0.75 2D 32 104 112 124 17.6 (132) 0.29 0.83
2E 56 113 120 136 16.9 (127) Crosslinked Crosslinked 2F 270 88 100
113 16.0 (120) 0.49 0.90 2G 280 88 100 113 16.0 (120) 0.30 0.91 2H
290 88 100 113 16.0 (120) 0.33 0.91 2I 300 88 100 102 16.0 (120)
0.14 0.75
Example 3
Continuous Synthesis of poly(styrene-methacrylic acid/anhydride)
via the p-toluenesulfonic Acid Catalyzed Hydrolysis of PS-t-BMA,
and Grafting of Amine Groups
[0137] This example illustrates an ability to create libraries by:
(1) varying the composition of the starting methacrylate copolymer
to be functionalized, (2) hydrolyzing high mol % P(t-BMA) content
block copolymers, (3) affecting the extent and nature of the
reaction products of deesterification by controlling pressure and
temperature and (4) varying the nature of reagents during
performance of in-situ grafting of acid and anhydride containing
materials with suitable nucleophiles. The continuous vacuum reactor
was modified by adding an entry port in Zone 3 of the LIST.
[0138] Six different samples of PS-t-BMA in toluene were made in a
stirred tubular reactor (STR) according to WO0158962, Example 6,
except the mole ratio of PS and t-BMA was varied, and the polymers
were dried. Each polymer was resolvated in toluene (19 Kg at solids
of 40 wt %) in a separate container. A reactant, p-toluenesulfonic
acid monohydrate (76 g), was added to each polymer solution in a wt
ratio of 1:100. The mixture was agitated with an air-powered
stirrer operating at 100 rpm at room temperature. The resultant
solutions were sequentially pumped (via a zenith pump at ca. 19.7
rpm) to the first zone of the continuous vacuum reactor. The mole
ratio of methacrylate (in the t-BMA) to PS and the time of entry
for each of the starting materials are shown in Table 4.
TABLE-US-00005 TABLE 4 When Fed Example (min) PS mole %
Methacrylate mole % 3A 0-120 95.3 4.7 3B 120-155 96.8 3.2 3C
155-201 78.0 22.0 3D 201-247 87.0 13.0 3E 247-296 80.1 19.9 3F
296-end 66.6 33.4
[0139] The speed of the main screw of the vacuum reactor was
maintained at approximately 34 rpm and the speed of the discharge
screw was maintained at approximately 136 rpm. Temperature and
vacuum settings were varied over time as shown in Table 5. At
different time intervals, various nucleophiles (cyclohexylamine,
butyl amine, ethanolamine) were fed into the start of zone 3 via a
reciprocating piston pump (at a rate of 10.0 g/min). The residence
time of the materials in the vacuum reactor was 35 minutes
[0140] Samples were tested with Diffusion Ordered Spectroscopy and
Infrared Spectroscopy. The results of the Diffusion Ordered
Spectroscopy showed the remaining levels of TBMA and levels of PS
in the reactor exit over time. These results are also shown in
Table 5. TABLE-US-00006 TABLE 5 Time Vacuum T.sub.1 T.sub.2 T.sub.3
TBMA TBMA PS Sample (min) kPa (torr) .degree. C. .degree. C.
.degree. C. Addition Mole % In Mole % Out Mole % 3G 0 26.8 (201)
128 171 166 3.2 0.20 99.80 3H 13 25.6 (192) 127 171 171 22.0 0.10
99.90 3I 18 18.0 (135) 127 172 169 0.30 99.69 3J 28 18.4 (138) 126
174 170 Cyclohexylamine 0.20 99.80 on 3K 37 17.5 (131) 128 174 172
0.20 99.80 3L 49 26.7 (200) 142 175 173 Cyclohexylamine 0.20 99.80
off 3M 63 26.8 (201) 146 176 174 13.0 1.65 98.35 3N 73 27.1 (203)
135 177 176 13.0 6.00 94.00 3O 84 27.3 (205) 132 176 176 Butylamine
on 13.0 7.15 92.85 at 89 min. 3P 99 27.1 (203) 135 181 178
Butylamine off 19.9 7.99 92.01 at 94 min. 3Q 117 24.9 (187) 141 183
181 Ethanolamine on 19.9 5.51 94.49 at 110 min. 3R 124 26.9 (202)
138 182 181 Ethanolamine off 19.9 2.27 97.73 at 133 min. 3S 143
20.8 (156) 138 189 182 33.4 0 100 3T 153 11.7 (83) 132 191 183 33.4
2.26 97.74 3U 172 6.5 (49) 127 188 184 33.4 0.51 99.42 3V 196 7.5
(56) 121 183 177 33.4 6.38 93.62 3W 206 7.7 (58) 131 175 168 33.4
12.07 87.93 3X 225 12.1 (91) 137 158 151 33.4 15.67 84.33
[0141] The data in Table 5 indicates that by varying temperature
and pressure in the process of the present invention, libraries of
materials can be made. Results of Infrared Spectroscopy indicated
characteristic bands for various functional groups. All samples
displayed the characteristic frequencies for anhydride (1802
cm.sup.-1 and 1760 cm.sup.-1) and acid (1710 cm.sup.-1 indicative
of a carboxylic acid). Ester groups (1736 cm.sup.-1 indicative of a
carboxylic ester) were also noted.
[0142] Grafting of an amine on the acid or anhydride sites was seen
after addition of cyclohexylamine. Sample 3M and 3N displayed new
bands indicative of amide formation (about 1671 cm.sup.-1) in
addition to anhydride (1803 cm.sup.-1 and 1760 cm.sup.-1).
[0143] The relative anhydride concentration was quantitatively
estimated by a ratio of the area under the pronounced anhydride
band at 1802 cm.sup.-1 with the area under the aromatic peak at
1600 cm.sup.-1, which was assumed to be constant. The anhydride
presence was seen to decrease with lower processing temperature.
Similarly the relative ester concentration was quantitatively
estimated by a ratio of the area under the pronounced ester band at
1736 cm.sup.-1 with the area under the aromatic peak at 1600
cm.sup.-1. The ester presence was seen to increase with lower
processing temperature. Data is shown in Table 6. TABLE-US-00007
TABLE 6 Anhydride Ester Sample Ratio of 1802 cm.sup.-1:1600
cm.sup.-1 Ratio of 1740 cm.sup.-1:1600 cm.sup.-1 3U 1.2 1.6 3X 0.5
3.2
[0144] Various modifications and alterations that do not depart
from the scope and spirit of this invention will become apparent to
those skilled in the art. This invention is not to be unduly
limited to the illustrative embodiments set forth herein.
* * * * *