U.S. patent application number 14/827270 was filed with the patent office on 2017-02-16 for polymer nanoparticle preparation by miniemulsion polymerization.
The applicant listed for this patent is King Abdulaziz City for Science and Technology (KACST). Invention is credited to AHMED ALI BASFAR, Klaus Jahnichen, Brigitte Voit.
Application Number | 20170044273 14/827270 |
Document ID | / |
Family ID | 56888906 |
Filed Date | 2017-02-16 |
United States Patent
Application |
20170044273 |
Kind Code |
A1 |
BASFAR; AHMED ALI ; et
al. |
February 16, 2017 |
POLYMER NANOPARTICLE PREPARATION BY MINIEMULSION POLYMERIZATION
Abstract
The present disclosure relates to a composition and a method to
prepare a polymer nanoparticle using miniemulsion polymerization
(MEP) comprising a monomer, a reactive co-stabilizer and a reactive
surfactant. The reactive co-stabilizer as disclosed is a
methacrylate containing perfluorinated or semifluorinated side
chains like 1H,1H,2H,2H-perfluorodecyl methacrylate
(H.sub.2F.sub.8MA). Further, the reactive stabilizer as used in the
preparation is cetyl trimethyl ammonium chloride (CTAB). The
polymer nanoparticle as formed has an enhanced stability and low
VOC as compared to a pure polymer prepared by MEP.
Inventors: |
BASFAR; AHMED ALI; (RIYADH,
SA) ; Jahnichen; Klaus; (Dresden, DE) ; Voit;
Brigitte; (Dresden, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
King Abdulaziz City for Science and Technology (KACST) |
RIYADH |
|
SA |
|
|
Family ID: |
56888906 |
Appl. No.: |
14/827270 |
Filed: |
August 14, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 3/04 20130101; G03G
9/08706 20130101; C08F 212/08 20130101; G03G 9/08708 20130101; G03G
9/08711 20130101; C08F 112/08 20130101; C08F 112/08 20130101; C08K
3/04 20130101; C08F 212/08 20130101; C08F 212/08 20130101; C08F
2/44 20130101; C08F 220/1804 20200201; C08F 2/24 20130101; C08F
220/22 20130101; C08F 112/08 20130101; C08F 2/24 20130101; C08L
25/06 20130101; G03G 9/0806 20130101; C08F 212/08 20130101; C08F
220/1804 20200201 |
International
Class: |
C08F 2/24 20060101
C08F002/24; C08K 3/04 20060101 C08K003/04; C08F 12/08 20060101
C08F012/08; C08F 2/44 20060101 C08F002/44; G03G 9/087 20060101
G03G009/087 |
Claims
1. A composition, comprising: a monomer; a reactive co-stabilizer;
and a reactive surfactant; wherein a polymer nanoparticle is
prepared using miniemulsion polymerization (MEP) wherein the
reactive co-stabilizer is a methacrylate derivative, wherein the
methacrylate derivative is a methacrylate containing perfluorinated
alcohol.
2. (canceled)
3. (canceled)
4. The composition according to claim 1, wherein the methacrylate
derivative is a methacrylate containing semi-fluorinated
alcohol.
5. The composition according to claim 1, wherein the reactive
surfactant is sodium dodecyl sulphate (SDS).
6. The composition according to claim 1, wherein the monomer is
styrene.
7. The composition according to claim 1, wherein the polymer
nanoparticle has a particle size in between 20 nm to 1000 nm.
8. The composition according to claim 1, wherein the composition
further comprise of a second monomer.
9. The composition according to claim 8, wherein the second monomer
is n-butyl acrylate (n-BuA).
10. A composition, comprising: a reactive co-stabilizer; a reactive
surfactant; a carbon black; and a polymer, wherein a polymer/carbon
black composite particle is prepared using MEP wherein the reactive
co-stabilizer is a methacrylate derivative, wherein the
methacrylate derivative is a methacrylate containing perfluorinated
alcohol.
11. (canceled)
12. (canceled)
13. The composition according to claim 10, wherein the methacrylate
derivative is a methacrylate containing semi-fluorinated
alcohol.
14. The composition according to claim 10, wherein the reactive
surfactant is cetyl trimethyl ammonium chloride (CTAB).
15. The composition according to claim 10, wherein the composite
particle is a polystyrene-carbon black (PSt/CB) composite
particle.
16. The composition according to claim 10, wherein the composite
particle has a particle size in between 20 nm to 1000 nm.
17. The composition according to claim 10, wherein the composite
particle has a zero volatile organic content (VOC).
18. The composition according to claim 10, wherein the composition
is used as a basic resin in a material for toner application.
Description
FIELD OF TECHNOLOGY
[0001] This disclosure relates generally to a polymer nanoparticle
preparation by microemulsion polymerization. More specifically,
this disclosure relates to a polymer nanoparticle by microemulsion
polymerization using reactive co-stabilizer and surfactant.
BACKGROUND
[0002] Nearly 40 years ago a special kind of emulsion
polymerization was firstly reported: the miniemulsion
polymerization (MEP) (Ugslstad et al., 1974). In this technique a
co-stabilizer, sometimes also called hydrophobe is used to retard
the diffusion of monomer molecules from smaller droplets to larger
ones (Ostwald ripening effect). Kinetically stable small monomer
droplets are formed in the presence of co-stabilizer and the
polymerization process can run in these droplets. Using this method
it is possible to polymerize water insoluble monomers because there
is no need to diffuse from the monomer droplets to the micelles
like in emulsion polymerization. In most of MEP a droplet
nucleation dominates. That means the polymerization takes place
inside the monomer droplets like in a suspension polymerization. As
a consequence very small particles can be obtained by this method
(<500 nm).
[0003] Besides the commonly used hydrophobic hexadecane (HD) as
co-stabilizer in MEP a large variety of substances was used as
co-stabilizer in MEP. However, there is still a lack of
co-stabilizers in the process of MEP that can provide enhanced
stability and low volatile organic content (VOC) to a polymer as
prepared by MEP.
SUMMARY
[0004] The present disclosure related to a composition and a method
of preparation of a polymer particle by MEP. Further, the present
disclosure relates to a composition and a method of preparation of
a polymer nanoparticle by MEP in the presence of reactive
co-stabilizer. In yet another embodiment, the present disclosure
relates to a composition and a method of preparation of a polymer
nanoparticle by MEP in the presence of a reactive surfactant. In
most embodiments, the reactive co-stabilizer comprises of a
methacrylate derivative.
[0005] In one embodiment, the present disclosure relates to a
composition comprising, a monomer, a reactive co-stabilizer and a
reactive surfactant, wherein a polymer nanoparticle is formed by
MEP. In another embodiment, the composition further comprise of
methacrylate containing perfluorinated alcohol as a co-stabilizer.
In yet another embodiment, the composition further comprise of
semi-fluorinated alcohol as a co-stabilizer. The perfluorinated or
semifluorinated co-stabilizer comprise of a side chain like
1H,1H,2H,2H-perfluorodecyl methacrylate (H.sub.2F.sub.8MA) as
reactive hydrophobe or co-stabilizer.
[0006] In one embodiment, the polymer particle as prepared has an
enhanced hydrophobicity owing to the formation of co-polymers
between styrene and co-stabilizer as compared to pure polymer by a
miniemulsion process using HD as a co-stabilizer. In another
embodiment, the polymer particle as prepared has a low VOC owing to
the polymerization of co-stabilizer as compared to a pure polymer
by a miniemulsion process using HD as a co-stabilizer.
[0007] In one embodiment, a preparation of a polymer nanoparticle
using a monomer, In another embodiment, the monomer is styrene (St)
is disclosed. In one embodiment, a second monomer may be introduced
along with St to prepare a polymer nanoparticle. In another
embodiment, the addition of the second polymer results in a tunable
glass transition temperature (Tg). The second monomer may be
n-butyl acrylate (n-BuA).
[0008] In one embodiment, a composition and a process of MEP of St
using H2F8MA as a co-stabilizer is disclosed. In another
embodiment, the process further comprise of using SDS as a reactive
surfactant.
[0009] In one embodiment, the polymer nanoparticles as produced by
MEP using reactive co-stabilizer such as perfluorinated or
semifluorinated alcohol. In another embodiment, the polymer
nanoparticles are produced by using a reactive surfactant. The
reactive surfactant may be a sodium dodecyl sulfate (SDS) or a
cetyl trimethyl ammonium chloride (CTAB).
[0010] In one embodiment, the size of polymer nanoparticles as
prepared is in the range of 20 nm to 1000 nm. In another
embodiment, the size of the polymer nanoparticles as prepared is in
the range of 50 nm to 300 nm. To obtain a range of 50 nm to 300 nm,
reactive co-stabilizer is added in 0.5 to 15 mol %, preferably 2-7
mol %, with regard to the primary monomer such as styrene.
[0011] In one embodiment, the present disclosure also relates to a
composition and a process of preparation of a polymer/carbon black
(CB) composite particle using MEP in the presence of a reactive
co-stabilizer and a reactive surfactant. In another embodiment, the
reactive co-stabilizer comprise of a methacrylate derivative. In
yet another embodiment, the reactive surfactant may be a sodium
dodecyl sulfate (SDS) or a cetyl trimethyl ammonium chloride
(CTAB). The composite particle as prepared is in the size range of
20 nm to 1000 nm in the presence of CB.
[0012] In one embodiment, the composition further comprise of
methacrylate containing perfluorinated alcohol as a co-stabilizer.
In yet another embodiment, the composition further comprise of
semi-fluorinated alcohol as a co-stabilizer. The perfluorinated or
semifluorinated co-stabilizer comprise of a side chain like
1H,1H,2H,2H-perfluorodecyl methacrylate (H.sub.2F.sub.8MA) as
reactive hydrophobe or co-stabilizer.
[0013] In one embodiment, the polymer/CB composite particle was
based on a polystyrene or a polystyrene dominated copolymers. In
another embodiment, the polymer/CB composite particle size was in
the range of 20 nm to 1000 nm and a low VOC content. The CB content
is in the range of 0.5-20 wt %, preferably 2-10 wt %, and the CB
has primary particles sizes between 20 and 60 nm, is high or low
structured, oxidized or non-oxidized, and shows pH values between 3
and 10.
[0014] In one embodiment, the polymer/CB composite particle
prepared in the presence of a reactive co-stabilizer and a reactive
surfactant has a low VOC. In another embodiment, the polymer/CB
composite particle as prepared has a zero VOC.
[0015] The above mentioned summary presents a simplified version of
one or more embodiments in order to provide a basic understanding
of such embodiments. This summary is not an extensive overview of
all contemplated embodiments, and is intended to neither identify
key or critical elements of all embodiments nor delineate the scope
of any or all embodiments. Its sole purpose is to present some
concepts of one or more embodiments in a simplified form as a
prelude to the more detailed description that is presented later.
Other aspects will be apparent from the following description,
figures and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 shows SEM picture of PSt/CB composite (5 wt %
PRINTex.RTM.150) using H.sub.2F.sub.8MA as co-stabilizer and CTAB
as surfactant.
[0017] FIG. 2 shows SEM picture of PSt/CB composite (5 wt %
PRINTex.RTM. 35) using H.sub.2F.sub.8MA as co-stabilizer and CTAB
as surfactant.
DETAILED DESCRIPTION
[0018] In the present invention, hydrophobic polymer nanoparticles
were prepared by the MEP technique using methacrylates based
semifluorinated or perfluorinated alcohols as the only
co-stabilizer or hydrophobe. Methacrylate containing perfluorinated
or semifluorinated alcohol comprise of side chains like
1H,1H,2H,2H-perfluorodecyl methacrylate (H.sub.2F.sub.8MA) (Formula
1) with the primary goal to act as reactive hydrophobe or
co-stabilizer and not as comonomer.
##STR00001##
[0019] Formula 1: Structure of 1H,1H,2H,2H-perfluorodecyl
methacrylate.
[0020] There is a significant difference between the mechanism of a
conventional emulsion and a MEP. MEP involves the use of an
effective surfactant and a co-stabilizer system to be in place and
produces very small monomer droplets. There can be a variety of
monomers and one can also use the prepared monomers as carriers.
The presence of surfactant and a co-stabilizer system retards
monomer diffusion from the submicron droplets. Both are necessary
to effect predominant droplet nucleation. A number of studies have
been conducted showing use of different types of surfactants and
co-stabilizers to carry out polymer formation with MEP.
[0021] The papers of Crespy (Crespy and Landfester, 2010) and
Antonietti (Antonietti and Landfester, 2002) give an overview about
the use of different co-stabilizers: reactive or unreactive low
molecular weight, oligomeric or polymeric substances.
[0022] Few papers described the preparation of fluorine containing
latexes by MEP and in those cases, the fluorinates compounds were
commonly used as classical comonomers, not as reactive
co-stabilizers or hydrophobes. Co-stabilizers and hydrophobes are
interchangele term and used in the same context throughout the
specification. Landfester (Landfester et al, 2002) described the
synthesis of latexes from the perfluorinated methacrylate
C.sub.2F.sub.6MA by MEP using SDS as surfactant and different
non-reactive perfluorocarbons as well as the classical HD as
co-stabilizer. It was a very convenient way to get latexes from
fluorinated monomers with a particle size ranging between 100 and
200 nm, which are usually not so easy to prepare. HD was not
suitable to prepare stable miniemulsions because of the
incompatibility with the fluorinated monomer. Also copolymers of
C.sub.2F.sub.6MA with St, MMA or n-BuA were synthesized by MEP. In
these experiments a 1:1 weight ratio between fluorene containing
monomer and non-fluorinated monomers was applied. SDS or CTAB were
used as surfactants. The experiments with St as comonomer and SDS
resulted in spherical particles (120-240 nm) with a relatively
broad particle size distribution. For all of the other recipes the
formation of non-spherical or open particles was observed. The
films formed from the latexes showed very high contact angles with
water as measuring liquid.
[0023] The preparation of a fluorinated acrylate latex was also
reported by Guo (Guo et al, 2014) using octamethyl
cyclotetrasiloxane and tetravinyl tetramethyl cyclotetrasiloxane as
co-stabilizers in MEP of MMA, n-BuA and dodecafluoroheptyl
methacrylate. The authors used 10, 20, and 40 mass % of the
fluorine containing monomers based on MMA/n-BuA.
[0024] Li (Li et al, 2008) reported in another paper the
copolymerization of MMA and n-BuA by MEP in the presence of
dodecafluoroheptyl methacrylate. It was discussed that the
co-stabilizer is formed during the polymerization. However, no
stable miniemulsions were formed with these systems. The final
products showed relatively broad particle size distributions or
even bimodal distributions.
[0025] Block copolymers from 2,3,4,5,6-pentafluorostyrene and St
were used together with perfluoromethyl cyclohexane as non-reactive
co-stabilizers for the MEP of Olefins using metallocenes as
catalysts by Nenov (Nenov et al, 2009). The resulting particles
showed a size of about 100 nm.
[0026] Pich (Pich et al, 2005) investigated the MEP of St and n-BuA
in the presence of a fluorine containing surfmer (ester made from
maleic anhydride and a perfluorinated C.sub.8 alcohol). In all of
the MEP experiments HD was added as co-stabilizer. It was found
that the maleic acid monoester was incorporated into the polymer
chain during the polymerization. With increasing amount of the
surfmer the particle size could be reduced as expected.
Furthermore, the preparation of very hydrophobic latexes could be
realized even at relatively low content of fluorine containing
surfmer when compared to a latex made from the fluorine containing
monomer C.sub.2F.sub.8MA in the presence of HD as
co-stabilizer.
[0027] Suzuki (Suzuki et al, 2005) investigated the preparation of
poly (C.sub.2F.sub.8MA) using SDS as surfactant and KPS as
initiator. No co-stabilizer was added. The particle size of the
droplets (standard experiment gave 190 nm) could be further
influenced by the variation of [SDS]. A range between 118 and 315
nm was realized. The reaction time until 100% conversion was
dependent on the particle size and ranged between 10 mm and 30 min.
The MEP of different acrylates from semifluorinated alcohols with
MMA and dodecyl methacrylate (LMA) in the presence of
CTAB/ethoxylated nonyl phenol mixtures as surfactant was also
investigated by Zhang (Zhang et al, 2007). The weight ratio of
F-acrylate to LMA to MMA was 4:3:3. Relatively broad particle size
distribution was reported for the obtained latex.
[0028] The commonly used low molecular weight co-stabilizers like
HD or hydrophobic oils have the drawback that they retain only
physically bound in the products after the polymerization reaction.
Finally, polymeric nanoparticles were obtained which still contain
volatile substances. Despite the boiling point of HD is relatively
high with about 287.degree. C., the thermogravimetric analysis of
pure HD showed evaporation at temperatures up to 200.degree. C.
with a T.sub.onset of 89.degree. C. and T.sub.10% of 133.degree. C.
(TGA under N.sub.2, 10K/min). The liberation of volatile substances
cannot be excluded in applications where higher temperatures are
not unusual. In order to reduce the VOC reactive co-stabilizers
replace the "volatile" HD.
[0029] The use of reactive co-stabilizers like H.sub.2F.sub.8MA
offers the possibility to get products with reduced VOC when
compared to the often used HD as co-stabilizer. Furthermore, it is
also possible to prepare polymer/CB composites by MEP using these
semifluorinated co-stabilizers. The T.sub.g of a copolymer depends
on the composition of the copolymers. Depending on the ratio of the
monomers used the T.sub.g of the final polymer can be tuned.
Furthermore, the addition of a second monomer like n-butyl acrylate
(n-BuA) resulted in the formation of copolymers of styrene and
n-BuA. T.sub.g of these formed copolymers can be tuned by the ratio
of St and n-BuA. Zero emission polymer or polymer/composite
particles can be achieved by replacing non only the co-stabilizer
but also the primary surfactant by a reactive, meaning
polymerizable surfactant.
[0030] The reactive co-stabilizer is incorporated by covalent bonds
into the polymer chain after the polymerization. Polymeric
particles of a highly hydrophobic nature in the range of 50 nm to
several 100 nm containing bound methacrylates with perfluorinated
or semi-fluorinated alcohols can be obtained by the described
process. The addition of a further monomer like n-BuA allows the
tuning of the T.sub.g of the copolymers if it is desired. The
replacement of the commonly used non-reactive surfactants SDS or
CTAB by a reactive surfactant like NaSS is also possible for the
MEP of monomers using fluorinated methacrylates as co-stabilizer.
By doing this, the content of low molecular weight components can
be reduced to nearly zero. Furthermore, polymer/carbon black (CB)
composite formation with CB content up to 10 wt % is also
possible.
[0031] Thus, the present invention discloses MEP of hydrophobic
monomers such as (but not limited to) Styrene (St) with
methacrylates based semifluorinated or perfluorinated alcohols as
co-stabilizer in the presence of a reactive surfactant such as CTAB
or other such surfactants. These methacrylates open an interesting
alternative to the commonly used co-stabilizers like HD or
methacrylates containing long alkyl chains. The co-stabilizer is
covalently bound into the polymer particles through
copolymerization with the primary monomer such as St. The use of a
methacrylate containing perfluorinated or semifluorinated side
chains like 1H,1H,2H,2H-perfluorodecyl methacrylate
(H.sub.2F.sub.8MA) with the primary goal to act as reactive
hydrophobe or co-stabilizer and not as co-monomer and without
adding any additional non-reactive co-stabilizer enhanced stability
of prepared polymer with using MEP technique.
EXPERIMENTAL
[0032] The following samples describe the preparation of PSt
nanoparticles by MEP using methacrylates from semi-fluorinated or
perfluorinated alcohols, especially H.sub.2F.sub.8MA as
co-stabilizer. Furthermore, the preparation of PSt (Polystyrene)/CB
(Carbon Black) composites by MEP with these special co-stabilizers
is also described.
Reagents and Materials
[0033] H.sub.2F.sub.8MA was purchased from ABCR. Styrene, n-Butyl
acrylate, CTAB, Sodium styrene sulfonate, HD,
2,2'-Azobis(2-methylpropionitrile) (AIBN), Phosphorous pentoxide,
calcium hydride, tetrahydrofurane, hexane and chloroform were
purchased from Sigma-Aldrich. SDS was purchased from Fluka.
Hydroxyaluminium bis[2-hydroxy-; 3,5-di t-butyl salicyic acid
Zirconium salicylate were purchased from Korean Material
technology. Methanol was purchased from ACROS. Carbon blacks such
as NIPex.RTM. 35 and NIPex.RTM. 150 were purchased from Evonik.
MEP of St Using H.sub.2F.sub.8MA as Co-Stabilizer (Examples 1-8 as
Shown in Table 1)
[0034] 4.27 g of purified St, 0.378 g H.sub.2F.sub.8MA (98%), and
0.135 g AIBN were weighted. After mixing by shaking the organic
phase the required amounts of surfactant SDS (0.051 g) and water
(41.6 g) were added. Then the mixture was slowly stirred with ca.
150 rpm under N.sub.2 (the needle for purging with N.sub.2 was not
in the mixture, very small stream of N.sub.2) for 15 mm During this
time the SDS was dissolved in water. A formation of pre-emulsion
was not observed because of the slow stiffing. Then the mixture was
stirred under N.sub.2 at 800 min.sup.-1 for 30 mm to prepare the
pre-emulsion using a glass stirrer. The distance between top side
fastener stirrer and lower side of the fastener motor was measured
and used in further experiments. So the stirring conditions were
comparable. After 30 mm the mixture was transferred to the
sonifier. During this a moderate stream of N.sub.2 was applied. The
miniemulsion was prepared by sonication of the pre-emulsion for 600
s (level 7, pulse, duty cycle 50%) with an ultrasonic disintegrator
Branson 450 W using a 1/2'' minitip. The connection between vessel
and tip was realized by a special Teflon adapter. Due to the
adapter a tight connection between minitip and vessel could be
realized. During all operations the vessel was purged with a slight
stream of nitrogen. A cooling of the reaction vessel by ice water
was performed during the sonication in order to avoid a heating of
the mixture. The reaction vessel with the formed miniemulsion was
transferred to the preheated thermostat (66.degree. C.). The
reaction was performed at 400 min.sup.-1 for 3 h. Then the mixture
was cooled to room temperature within 5 min using ice-water. Before
the storage of the dispersion, ca. 200 mg of a 1 wt % solution of
HQ in water was added and the mixture was shaken.
[0035] For the samples 7 and 8 (Table 1) n-BuA was added to the St.
Then the experiments were performed as described above for 4 h
instead of 3 h without n-BuA. Dispersions with 20 wt % solid
content showed a very high viscosity. Following the addition of
n-BuA, resulting dispersion showed a very high viscosity. They were
hardly to stir. Consequently, the solid content of the total
mixture was reduced to 10 wt %, (see Table 1).
Removal of Coagulum
[0036] After the polymerization, the formed dispersion was poured
through a mesh (pore size 20 .mu.m.times.20 .mu.m) and then used
for the analytical investigations. Finally, the rest in the mesh
and the rests from the stirrer and the vessel were transferred into
a frit using water. The coagulum was washed with water and dried in
vacuum at room temperature in order to determine the quantity of
coagulum.
Determination of Conversion
[0037] Three samples of 2 g of the formed dispersion were weighted
in a petri dish and kept overnight at room temperature. The air
dried products were dried in vacuum at room temperature until the
weight was constant. P.sub.4O.sub.10 was used as drying agent in
the vacuum oven.
Size Exclusion Chromatography (SEC)
[0038] SEC measurements were performed with an apparatus of the
Agilent Series 1100 (RI detection, 1PL_MIXED-B-LS-column
(7.5.times.300 mm) and 10 .mu.m PSt gel Agilent column, Chloroform
1.0 mL/min). PSt was used as standard. This was the standard method
for all of the samples. The samples containing CB were filtrated to
remove the CB before the analysis. The error of the method is about
10%.
Particle Size Measurements
[0039] The particle size measurements were performed with a
Zetasizer NANO S (Malvern) at a fixed scattering angle of
173.degree.. The given values as shown in Table 2 are the Z.sub.ave
(intensity based). The error of the measurements is about 5%.
Higher values of particle size distribution index (PDI), as shown
in Table 2 mean that the particle size distribution becomes
broader.
Preparation of Samples for the DLS Measurements
[0040] The measurements were performed in 0.01 N NaCl solutions
according to the Malvern recommendation for the measurements of
latex standards. For the experiments with 20 wt % solid content ca.
250 mg of the dispersion was weighted and ca. 20 g of 0.01 N NaCl
solution was added. For the samples with lower solid content (10 or
15 wt %) the amount of NaCl solution was proportionally reduced to
keep the concentration of the thinned dispersions nearly constant.
The particle sizes of 3 samples were estimated, every of them was
consecutively measured twice. In few cases the application of NaCl
solution led to a precipitation of the dispersion. Therefore, the
dispersion was thinned only with pure Millipore water.
Scanning Electron Microscopy (SEM)
[0041] The SEM investigations were performed with an Ultra 55 plus
(Zeiss). The thinned dispersions from the DLS measurements were
used to prepare the samples. One drop was placed on a purified
silicon wafer mounted at a sample holder. After air drying the
samples were sputtered with 3 nm Pt. Preparation of PSt/CB
composites using H.sub.2F.sub.8MA and different surfactants such as
SDS, CTAB and NaSS (as shown in examples 9-11 in Table 1).
Following polymerization, a part of the resultant dispersion was
thinned with 0.01 normal NaCl solution in deionized water (200-250
mg dispersion were thinned with 10 g of NaCl solution). This
thinned dispersions were used for the particle size measurements as
well as for the SEM investigations. The picture shows the particles
of PSt/CB composite (5 wt % PRINTex.RTM.150) which were obtained by
the MEP of St in the presence of CB. The fluorinated monomer
H.sub.2F.sub.8MA was used as co-stabilizer instead of the often
used hexadecane as co-stabilizer. Most probably, the small
spherical particles consist of unmodified polymer particles (not
marked). Larger spherical and particles (white marked) and
asymmetrical (black marked) represent the formed St/CB composites.
Beside modified CB particles also unmodified CB was detected
(circled) (FIG. 1). As shown in FIG. 2, for the experiment with
PRINTex.RTM. 35 no unmodified CB was detected by SEM
investigations. It is assumed that the large particles contain the
CB.
[0042] In MEP experiments with St replacing HD by H.sub.2F.sub.8MA
a very stable miniemulsion was obtained and polystyrene particles
with diameters below 200 nm resulted. Best results are obtained
using 1-7 mol % H.sub.2F.sub.8MA (based on styrene) (Tables 1 and
2). For comparison, a reference sample using SDS as surfactant and
HD as co-stabilizer is given in Tables 1 and 2. The MEP of St in
the presence of HD resulted in small particles of 78 nm (z.sub.ave,
intensity based) with a PDI of 0.06. However, the SEM
investigations showed also a small amount of particles in the .mu.m
scale as unwanted side products. The replacement of HD by the
fluorinated monomer H.sub.2F.sub.8MA let to a nearly doubling of
the particle size from 78 to 126-135 nm. The PDI of the latexes
prepared with a comparable ratio of surfactant SDS and
co-stabilizer can be increased for the samples with
H.sub.2F.sub.8MA without compromising the positive MEP results. A
decrease of PDI was realized by the use of up to 4-7 mol %
H.sub.2F.sub.8MA (based on St, examples 3, 4 shown in Table 2). A
further improvement of PDI (reduction) can be realized by the
replacement of the commonly used SDS by the cationic surfactant
CTAB (examples 5, 6). Even with small amount of H.sub.2F.sub.8MA (3
mol % based on St) very nicely evenly distributed particles were
obtained. Generally, the conversion of the monomers was above 90%
in all of the runs with SDS or CTAB and the amount of coagulum was
nearly negligible. The incorporation of the fluorinated
methacrylate did not show any influence on the T.sub.g of the
resulting copolymers. In order tune the T.sub.g a 2.sup.nd monomer
can be incorporated. The copolymerization of St and nBuA (8 mol %
n-BuA) by MEP technique was also performed using H.sub.2F.sub.8MA
as co-stabilizer. Monomer conversion>95% was obtained after 4 h
polymerization time. The particle size of 121 nm (Z.sub.ave,
intensity based) was in a comparable range to the samples using
only St. The MEP of St was also performed using a reactive
surfactant like sodium styrene sulfonate (NaSS) and
H.sub.2F.sub.8MA as co-stabilizer (example 8). The particle size
increased from 121 to 157 but the particle size distribution
dropped from 0.06 to 0.02. This offers the possibility for the
preparation of F-containing latexes having ionic groups at the
surface of the particles. Samples containing NaSS were not soluble
in organic solvents like chloroform or THF. The use of a cationic
monomer vinyl benzyl trimethylammonium chloride as reactive
surfactant in the system St/H.sub.2F.sub.8MA is also possible.
[0043] For the first time MEP of St/CB composites were successfully
performed in the presence of a methacrylate based on fluorinated or
semifluorinated alcohol like H.sub.2F.sub.8MA as co-stabilizer.
CTAB was the most effective surfactant for the preparation of the
St/CB composites. The content of CB can be varied between 0 and 10
mass % (based on St). Spherical and asymmetric polymer particles in
the range between 100-200 nm were observed demonstrating effective
preparation of polymer composite particles and polymer covered CB,
see FIGS. 1 and 2. High monomer conversion>90% can be achieved
by further optimization of polymerization conditions.
Preparation of PSt/CB Composite Particle Using H.sub.2F.sub.8MA and
Different Surfactants (Examples 9-11 as Shown in Table 1)
[0044] Two different CB types (but not limited to) NIPex.RTM. 35
and NIPex.RTM. 150 were selected for the preparation of PSt/CB
composite particle. NIPex.RTM. 35 is a non-oxidized, low structure
furnace black with a mean primary particle size of about 31 nm and
a pH value of about 9 (according to DIN ISO 787/9). NIPex.RTM. 150
is a high structure oxidized gas black with a mean primary particle
size of about 25 nm and a pH value of about 4 (according to DIN ISO
787/9). The procedure as described for MEP of St using
H.sub.2F.sub.8MA as co-stabilizer is repeated using the recipe
described in the 2.sup.nd part of Table 1. The CB was added to the
organic phase at the beginning and the organic phase was shaken.
Then water and the surfactant were added to the mixture and was
processed. The polymer/CB composite particle as prepared using a
reactive, fluorinated co-stabilizer can be used as a basic resin in
materials for toner applications, however, the use is not limited
to the field of toner applications.
[0045] Table 1 shows recipes for the MEP experiments using
H.sub.2F.sub.8MA as co-stabilizer
TABLE-US-00001 Water Styrene Surfactant Hydrophobe AIBN Filler
Example [g] [g] Type [mg] Type [mg] [mg] Type [mg] [wt %]* 0 37.7
8.6 SDS 103 HD 359 269 without 0 0 Reference 1 41.7 4.3 SDS 51
H.sub.2F.sub.8MA 692 135 without 0 0 2 41.6 4.3 SDS 59
H.sub.2F.sub.8MA 1102 133 without 0 0 3 41.7 4.3 SDS 51
H.sub.2F.sub.8MA 1519 135 without 0 0 4 41.6 4.3 SDS 105
H.sub.2F.sub.8MA 1467 134 without 0 0 5 41.6 4.28 CTAB 131
H.sub.2F.sub.8MA 730 134 without 0 0 6 41.6 4.29 CTAB 132
H.sub.2F.sub.8MA 1460 133 without 0 0 7 41.6 3.9/0.46.sup.a CTAB
130 H.sub.2F.sub.8MA 731 134 without 0 0 8 37.7 7.8/0.8.sup.b NaSS
103 H.sub.2F.sub.8MA 357 134 without 0 0 9 41.6 4.28 CTAB 65
H.sub.2F.sub.8MA 731 133 CB150 214 5 10 41.6 4.28 CTAB 130
H.sub.2F.sub.8MA 731 134 CB150 214 5 11 41.6 4.28 CTAB 65
H.sub.2F.sub.8MA 730 133 CB35 214 5 *based on St .sup.a10 wt %
n-BuA based on St=, polymerization for 4 h .sup.b9 wt % n-BuA based
on St=, polymerization for 4 h
[0046] Table 2 shows results obtained for the MEP of St using
H.sub.2F.sub.8MA as co-stabilizer.
TABLE-US-00002 Particle size Con- DLS SEC ver- Coag- z-ave M.sub.n
M.sub.w M.sub.w/ sion ulum Example [nm] PDI [g/mol] [g/mol] M.sub.n
[%] [%] 0 78 0.06 149000 693000 4.7 94 0.3 (Reference) 1 126 0.10
76000 438000 5.8 92 0.7 2 135 0.08 72000 364000 5.1 95 0.6 3 134
0.05 77000 376000 4.9 94 0.1 4 135 0.04 71000 286000 4.0 97 0.1 5
.sup. 130.sup.a 0.04 68000 316000 4.6 94 0.1 6 .sup. 115.sup.a 0.05
99000 480000 4.8 97 0.1 7 121 0.06 69000 329000 4.8 99 0.2 8 157
0.02 not soluble 95 3 9 167 0.1 66000 341000 5.2 86 2.8 10 .sup.
141.sup.b 0.04.sup.b 105000 476000 4.5 89 3.6 11 133 0.11 82000
472000 5.8 67 3.5 .sup.avery nicely distributed particles with only
few medium sized particles .sup.bmeasurement of particle size was
performed in pure water. The use of NaCl solution resulted in
flocculation of latex.
[0047] Although the present embodiments have been described with
reference to specific example embodiments, it will be evident that
various modifications and changes may be made to these embodiments
without departing from the broader spirit and scope of the various
embodiments. Accordingly, the specification and drawings are to be
regarded in an illustrative rather than a restrictive sense.
* * * * *