Styrene carboxylation

Many ionogenic monomers containing a polymerizable carbon double bond have been reported in the literature, and therefore a wide variety of anionic, cationic, and amphophilic polyelectrolytes may be synthesized using free radical polymerizations. Examples of anionic ionogenic monomers which have been used to synthesize anionic polyelectrolytes include acrylic acid [4-10], methac-rylic acid [6-8,11,12], sodium styrenesulfonate [7,13,14], p-styrene carboxylic... 

At present work the following large-capacity polymers were taken as polymeric basis acrylate-styrene carboxylated latex - Lentex A4 (TU 2241-001-47923137-01) copolymer of... 

SWNT/copolymers of styrene Carboxylic acid casting Solution 1.5 2.1 5 24.25 2006... 

In a second experiment [128] they selected a butadiene-styrene-carboxyl-ate rubber because of its compatibility with polyethylene and its ability... 

Until recently, there was only one report about the use of reactive costabilizers in miniemulsion polymerization [125]. In that study, dodecyl methacrylate (DMA) and stearyl methacrylate (SMA) were been used as cosurfactants with SDS and compared with cetyl alcohol (CA) and hexadecane (HD). It has been shown that DMA behaves like CA, whereas SMA displays a behavior similar to HD in terms of droplet size stability as well as in the particle size distribution of latexes. However, the distribution obtained using these reactive hydrophobes is in both cases somewhat narrower than for the model compounds. More recently, the same team published a study where in the polymerization of styrene in miniemulsions stabilized using DMA or SMA, small quantities of acrylic acid or methacrylic acid were added [126]. The authors were chiefly interested in the nucleation mechanism. Surprisingly, the addition of these hydrophilic monomers tends to favor nucleation within the droplets more than homogeneous nucleation, which is the dominating mechanism in the absence of these water-soluble monomers. The explanation lies in the fact that the styrene-carboxylic co-oligomers, because they are much more hydrophilic, are more reluctant to nucleate new particles. 

Poly(styrene carboxylic acid) -FcHj-ch J n o COOH Poly(2-acrylamido-2-methyl-l-propane sulfonic acid) (HPAMS) CH3 0 NH H-C—CHj 1 CH2 1 SO3H... 

To illustrate the specific operations involved, the scheme below shows the first steps and the final detachment reaction of a peptide synthesis starting from the carboxyl terminal. N-Boc-glycine is attached to chloromethylated styrene-divinylbenzene copolymer resin. This polymer swells in organic solvents but is completely insoluble. ) Treatment with HCl in acetic acid removes the fert-butoxycarbonyl (Boc) group as isobutene and carbon dioxide. The resulting amine hydrochloride is neutralized with triethylamine in DMF. 

Acrylics. Acetone is converted via the intermediate acetone cyanohydrin to the monomer methyl methacrylate (MMA) [80-62-6]. The MMA is polymerized to poly(methyl methacrylate) (PMMA) to make the familiar clear acryUc sheet. PMMA is also used in mol ding and extmsion powders. Hydrolysis of acetone cyanohydrin gives methacrylic acid (MAA), a monomer which goes direcdy into acryUc latexes, carboxylated styrene—butadiene polymers, or ethylene—MAA ionomers. As part of the methacrylic stmcture, acetone is found in the following major end use products acryUc sheet mol ding resins, impact modifiers and processing aids, acryUc film, ABS and polyester resin modifiers, surface coatings, acryUc lacquers, emulsion polymers, petroleum chemicals, and various copolymers (see METHACRYLIC ACID AND DERIVATIVES METHACRYLIC POLYMERS). 

One method (116) of producing cellular polymers from a variety of latexes uses primarily latexes of carboxylated styrene—butadiene copolymers, although other elastomers such as acryUc elastomers, nitrile mbber, and vinyl polymers can be employed. 

Hydroxybenzaldehydes readily react with compounds containing methyl or methylene groups bonded to one or two carboxyl, carbonyl, nitro, or similar strong electron-withdrawing groups. The products are usually P-substituted styrenes. 4-Hydroxybenzaldehyde, for example, reacts with 2-methylquinazolines (where R = H, Cl) to give compounds which have anti-inflammatory activity (59). 

In addition to providing fully alkyl/aryl-substituted polyphosphasenes, the versatility of the process in Figure 2 has allowed the preparation of various functionalized polymers and copolymers. Thus the monomer (10) can be derivatized via deprotonation—substitution, when a P-methyl (or P—CH2—) group is present, to provide new phosphoranimines some of which, in turn, serve as precursors to new polymers (64). In the same vein, polymers containing a P—CH group, for example, poly(methylphenylphosphazene), can also be derivatized by deprotonation—substitution reactions without chain scission. This has produced a number of functionalized polymers (64,71—73), including water-soluble carboxylate salts (11), as well as graft copolymers with styrene (74) and with dimethylsiloxane (12) (75). 

Functionalization. Copolymers do not have the abiHty to exchange ions. Such properties are imparted by chemically bonding acidic or basic functional groups to the aromatic rings of styrenic copolymers, or by modifying the carboxyl groups of the acryHc copolymers. There does not appear to be a continuous functionalization process on a commercial scale. 

Many synthetic latices exist (7,8) (see Elastomers, synthetic). They contain butadiene and styrene copolymers (elastomeric), styrene—butadiene copolymers (resinous), butadiene and acrylonitrile copolymers, butadiene with styrene and acrylonitrile, chloroprene copolymers, methacrylate and acrylate ester copolymers, vinyl acetate copolymers, vinyl and vinyUdene chloride copolymers, ethylene copolymers, fluorinated copolymers, acrylamide copolymers, styrene—acrolein copolymers, and pyrrole and pyrrole copolymers. Many of these latices also have carboxylated versions. 

Other Organolithium Compounds. Organoddithium compounds have utiHty in anionic polymerization of butadiene and styrene. The lithium chain ends can then be converted to useflil functional groups, eg, carboxyl, hydroxyl, etc (139). Lewis bases are requHed for solubdity in hydrocarbon solvents. 

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). 

Other polymers used in the PSA industry include synthetic polyisoprenes and polybutadienes, styrene-butadiene rubbers, butadiene-acrylonitrile rubbers, polychloroprenes, and some polyisobutylenes. With the exception of pure polyisobutylenes, these polymer backbones retain some unsaturation, which makes them susceptible to oxidation and UV degradation. The rubbers require compounding with tackifiers and, if desired, plasticizers or oils to make them tacky. To improve performance and to make them more processible, diene-based polymers are typically compounded with additional stabilizers, chemical crosslinkers, and solvents for coating. Emulsion polymerized styrene butadiene rubbers (SBRs) are a common basis for PSA formulation [121]. The tackified SBR PSAs show improved cohesive strength as the Mooney viscosity and percent bound styrene in the rubber increases. The peel performance typically is best with 24—40% bound styrene in the rubber. To increase adhesion to polar surfaces, carboxylated SBRs have been used for PSA formulation. Blends of SBR and natural rubber are commonly used to improve long-term stability of the adhesives. 

For acrylate polymers with higher levels of carboxylic acids, THF can be modified by the addition of acids such as acetic, phosphoric, or trifluoroacetic. Levels as high as 10% acetic acid are considered acceptable by most manufacturers for their styrene/DVB columns. If such a modified mobile phase is used, it may need to be premixed rather than generated using a dynamic mixing HPLC pump because on-line mixing often leads to much noisier baselines, particularly when using a refractive index detector. 

Both R and MMA radicals are found to be responsible for the photoinitiation process. Chaturvedi and coworkers [54,55] introduced phenyl dimethyl sulfonium-ylide cupric chloride and chromium thiophene carboxylate as the photoinitiator of styrene and MMA. No reaction mechanism was given for these systems. 

Polymers can be modified by the introduction of ionic groups [I]. The ionic polymers, also called ionomers, offer great potential in a variety of applications. Ionic rubbers are mostly prepared by metal ion neutralization of acid functionalized rubbers, such as carboxylated styrene-butadiene rubber, carboxylated polybutadiene rubber, and carboxylated nitrile rubber 12-5]. Ionic rubbers under ambient conditions show moderate to high tensile and tear strength and high elongation. The ionic crosslinks are thermolabile and, thus, the materials can be processed just as thermoplastics are processed [6]. 

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