Latex copolymerization

Stage, more methyl methacrylate and ethyl acrylate were added. The resultant latex was dried, ground to a fine powder and with melting and kneading combined with a methyl methacrylate-co-ethyl acrylate resin. The final composition was said to exhibit improved physical properties [79]. While this patent is somewhat overly complex, our main point is that evidently allyl methacrylate may be incorporated readily in a conventional latex copolymerization process. 

The latex copolymerization of styrene with A -methylacrylamide does not follow the three stage process observed with the other acrylamide derivatives. 

Frequent high salinity levels as a result of certain processes (alkylation, latex copolymerization, chlorohydrin process, etc.). Salinity can range from 5 to 25 g l of NaCI- base, CaCl2 base or less often NH Cl-base salts. Salinity is lowered if effluents are mixed 50% with cooling blowdown water (salinity from 0.6 to 3 g l ) ahead of general biological purification. 

AH-acryHc (100%) latex emulsions are commonly recognized as the most durable paints for exterior use. Exterior grades are usuaHy copolymers of methyl methacrylate with butyl acrylate or 2-ethyIhexyl acrylate (see Acrylic ester polymers). Interior grades are based on methyl methacrylate copolymerized with butyl acrylate or ethyl acrylate. AcryHc latex emulsions are not commonly used in interior flat paints because these paints typicaHy do not require the kind of performance characteristics that acryHcs offer. However, for interior semigloss or gloss paints, aH-acryHc polymers and acryHc copolymers are used almost exclusively due to their exceUent gloss potential, adhesion characteristics, as weU as block and print resistance. 

Vinyl acetate is another monomer used in latex manufacture for architectural coatings. When copolymerized with butyl acrylate, it provides a good balance of cost and performance. The interior flat latex paint market in North America is almost completely dominated by vinyl acetate—acryHc copolymers. Vinyl acetate copolymers are typicaHy more hydrophilic than aH-acryHc polymers and do not have the same ultraviolet light resistance as acryHcs as a result. 

Almost all synthetic binders are prepared by an emulsion polymerization process and are suppHed as latexes which consist of 48—52 wt % polymer dispersed in water (101). The largest-volume binder is styrene—butadiene copolymer [9003-55-8] (SBR) latex. Most SBRlatexes are carboxylated, ie, they contain copolymerized acidic monomers. Other latex binders are based on poly(vinyl acetate) [9003-20-7] and on polymers of acrylate esters. Poly(vinyl alcohol) is a water-soluble, synthetic biader which is prepared by the hydrolysis of poly(viayl acetate) (see Latex technology Vinyl polymers). 

Continuous emulsion copolymerization processes for vinyl acetate and vinyl acetate—ethylene copolymer have been reported (59—64). CycHc variations in the number of particles, conversion, and particle-size distribution have been studied. Control of these variations based on on-line measurements and the use of preformed latex seed particles has been discussed (61,62). 

Continuous polymerization systems offer the possibiUty of several advantages including better heat transfer and cooling capacity, reduction in downtime, more uniform products, and less raw material handling (59,60). In some continuous emulsion homopolymerization processes, materials are added continuously to a first ketde and partially polymerized, then passed into a second reactor where, with additional initiator, the reaction is concluded. Continuous emulsion copolymerizations of vinyl acetate with ethylene have been described (61—64). Recirculating loop reactors which have high heat-transfer rates have found use for the manufacture of latexes for paint appHcations (59). 

T and are the glass-transition temperatures in K of the homopolymers and are the weight fractions of the comonomers (49). Because the glass-transition temperature is directly related to many other material properties, changes in T by copolymerization cause changes in other properties too. Polymer properties that depend on the glass-transition temperature include physical state, rate of thermal expansion, thermal properties, torsional modulus, refractive index, dissipation factor, brittle impact resistance, flow and heat distortion properties, and minimum film-forming temperature of polymer latex... 

Table 9 The Dispersion Copolymerization Procedures Used for the Synthesis of Uniform Latex Particles...

As shown for the synthesis of PS [291], the monomer may be localized in the vicinity of the filler surface by previously grafting a polymer capable of swelling in the base monomer. Copolymeric latex of polychloroprenemethacrylic acid was added to the aqueous dispersion of chalk. The acid groups reacted with chalk and the latex particles became chemically grafted to chalk. When further portions of styrene were added they were completely absorbed by modified chalk. 

Data of Nomura and Funita (12). The predictive capabilities of EPM for copolymerizations are shown in Figures 8-9. Nomura has published a very extensive set of seeded experimental data for the system styrene-MMA. Figures 8 and 9 summarize the EPM calculations for two of these runs which were carried out in a batch reactor at 50 °C at an initiator concentration of 1.25 g dm 3 water. The concentration of the seeded particles was 6x10 dm 3 and the total mass of monomer was 200 g dm 3. The ratio of the mass of MMA to the total monomer was 0.5 and 0.1 in Figures 8 and 9 respectively. The agreement between the measured and predicted values of the total monomer conversion, the copolymer composition, and the concentration of the two monomers in the latex particles is excellent. The transition from Interval II to Interval III is predicted satisfactorily. In accordance with the experimental observations, EPM predicted no new particle formation under the conditions of this run. 

Two different emulsion polymerization reactions were Investigated. One was the polymerization of acrylonitrile and methylacrylate (75/25 AN/MA) In the presence of an acrylonitrile elastomer (70/30 BD/AN) to produce a graft resin, llie second was the copolymerization oiE acrylonitrile and styrene (70/30 AN/S). Chromatographic analyses of latex solutions were conducted periodically during both types of polymerization reactions, using acetonitrile as latex solvent and chromatographic mobile phase. 

However, the mechanism of action of filtration control additives is not yet completely understood. Examples are bentonite, latex, various organic polymers, and copolymers. Many additives for fluid loss are water-soluble polymers. Vinyl sulfonate fluid loss additives based on the 2-acrylamido-2-methyl-propane sulfonic acid (AMPS) monomer are in common use in field cementing operations [363]. The copolymerization of AMPS with conjugate monomers yields a fluid loss agent whose properties include minimal retardation, salt tolerance, high efficiency, thermal stability, and excellent solids support. 

Acrylic resins are generally well characterized by Py-GC/MS without the need for any derivatization reaction. However, in waterborne polymer dispersions it is common to have minor amounts of acrylic and/or methacrylic acid monomers added in the copolymerization to help the stability of the final latex. These monomers can also appear in the pyrolysis products, and it has been shown that with on-line derivatization they can be more efficiently revealed [85]. 

Styrene-butadiene copolymer(s) (latex), 23 367, 389-390 from butadiene, 4 375, 383, 384t compatibilization efficiency of, 20 336 Styrene-butadiene copolymerization, 14 256... 

Copolymerization of vii rl acetate with aciylic monomers can lead to the production of latex having a wide range of mechanical and molecular properties depending on the molecular stracture of the emulsifier, and also above parameters. 

Another approach to producing latexes with chemically bound surface-active groups is to use a reactive surfactant—a surfactant with a polymerizable double bond, such as sodium dodecyl allyl sulfosuccinate [Wang et al., 2001a,b,c]. Copolymerization of the reactive surfactant with the monomer of interest binds the surface active groups into the polymer chains. 

Styrene-1,3-butadiene copolymers with higher styrene contents (50-70%) are used in latex paints. Styrene and 1,3-butadiene terpolymerized with small amounts of an unsaturated carboxylic acid are used to produce latexes that can be crosslinked through the carboxyl groups. These carboxylated SBR products are used as backing material for carpets. Styrene copolymerized with divinyl benzene yields crosslinked products, which find use in size-exclusion chromatography and as ion-exchange resins (Sec. 9-6). 

The reaction described in this example is carried out in miniemulsion.Miniemulsions are dispersions of critically stabilized oil droplets with a size between 50 and 500 nm prepared by shearing a system containing oil, water,a surfactant and a hydrophobe. In contrast to the classical emulsion polymerization (see 5ect. 2.2.4.2), here the polymerization starts and proceeds directly within the preformed micellar "nanoreactors" (= monomer droplets).This means that the droplets have to become the primary locus of the nucleation of the polymer reaction. With the concept of "nanoreactors" one can take advantage of a potential thermodynamic control for the design of nanoparticles. Polymerizations in such miniemulsions, when carefully prepared, result in latex particles which have about the same size as the initial droplets.The polymerization of miniemulsions extends the possibilities of the widely applied emulsion polymerization and provides advantages with respect to copolymerization reactions of monomers with different polarity, incorporation of hydrophobic materials, or with respect to the stability of the formed latexes. 

Succinimide-group-earrying latex particles are another versatile reactive support (12). The fraction of active succinimide groups on the particle surface was measured to be about 1% of succinimide monomer charged for the heterogeneous copolymerization with diethylene glycol methacrylate. 

The polymerization of a mixture of more than one monomer leads to copolymers if two monomers are involved and to terpolymers in the case of three monomers. At low conversions, the composition of the polymer that forms from just two monomers depends on the reactivity of the free radical formed from one monomer toward the other monomer or the free radical chain of the second monomer as well as toward its own monomer and its free radical chain. As the process continues, the monomer composition changes continually and the nature of the monomer distribution in the polymer chains changes. It is beyond the scope of this laboratory manual to discuss the complexity of reactivity ratios in copolymerization. It should be pointed out that the formation of terpolymers is even more complex from the theoretical standpoint. This does not mean that such terpolymers cannot be prepared and applied to practical situations. In fact, Experiment 5 is an example of the preparation of a terpolymer latex that has been suggested for use as an exterior protective coating. 

Since this work was directed toward potential commercialization, it utilized the various modes of copolymerization or polymerization systems - solution, suspension, and latex. 

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