STYRENE-VINYLPYRIDINE

Acrylonitrile Allyl acrylate Allyl methacrylate n-Butyl acrylate n-Butyl methacrylate Isobutyl methacrylate Divinyl benzene 2-Choroethyl methacrylate Ethyl acrylate /i-Ethoxyethyl methacrylate 2-Ethylhexyl methacrylate Ethyl methacrylate Methyl methacrylate Methylisopropenylketone Methyl vinyl ketone N-Vinyl pyrrolidone Styrene Vinylpyridine Acrylonitrile Allyl acrylate Allyl methacrylate... 

With the purpose of increasing the range of available block copolymers, comonomers other than methacrylates and acrylates can also be involved in sequential polymerization, provided that they are susceptible to anionic polymerization. Dienes, styrene derivatives, vinylpyridines , oxiranes and cyclosiloxanes are examples of such comonomers. The order of the sequential addition is, however, of critical importance for the synthesis to be successful. Indeed, the pX a of the conjugated acid of the living chain-end of the first block must be at least equal to or even larger than that of the second monomer. Translated to a nucleophilicity scale, this pK effect results in the following order of reactivity dienes styrenes > vinylpyridines > methacrylates and acrylates > oxiranes > siloxanes. 

All three processes are very useful because of their efficiency and ease of use in a wide range of reaction types (bulk, solution, emulsion, and suspension) and their tolerance toward water and oxygen impurities. These are important advantages in industrial practice. Purification and separation are tedious and cosdy. ATRP and RAFT polymerization have been applied to the polymerization of a wide range of monomers (e.g., methaaylates, aaylates, styrenes, vinylpyridines, acrylonitrile, and acrylamides), while the range afforded by NMP has been more limited. NMP is best suited to styrenes and its copolymers, although new nitroxides have allowed the polymerization of methacrylates and acrylates. 

Fig. 9.3 a, b. Phase diagram in butanone of a copoly(methyl methacrylate-methacrylic acid) and b copoly(styrene-vinylpyridine) according to Morawetz et al. [16]. The contents in methacrylic acid and vinylpyridine (percent of monomer units in the chains) are respectively a. 0% 0% (homopolymers) — —... 

Effect of the Substituent A If the substituent promotes a delocalization of the negative charge [as is the case for styrene, vinylpyridines, (meth)acry-lates, etc.], it entails a decrease of the intrinsic reactivity of the carbanionic species. Thus, in the case of acrylates, the active center is an enolate of rather low reactivity ... 

Vinyl pyridine-grafted polyolefins [229] having improved dyeability were prepared with >0.02 wt% based on the monomer of a perester catalyst and >0.1 wt% based on the monomer of a reducing agent promoter selected from lower-valent salts of multivalent metals, hydrosulfite, or alkali metal formaldehyde sulfoxylate. Thus, the polypropylene-styrene-vinylpyridine-graft copolymer prepared in the presence of 1 wt% sodium hydrosulfite and 0.5 wt% tert-huiyl 2-ethyl perhexanoate at 90 C was melt-spun into fibers... 

Star block copolymers in which each branch is an amphiphilic star block copol)nners can be obtained in a similar way. The polymerization of the second monomer can be initiated by the carbanions of the first one, that is, in the order of increasing electroaffinity. Typical examples include styrene/butyl methacrylate [75] and styrene/vinylpyridine [76]. 

Copolymerization can be carried out with styrene, acetonitrile, vinyl chloride, methyl acrylate, vinylpyridines, 2-vinylfurans, and so forth. The addition of 2-substituted thiazoles to different dienes or mixtures of dienes with other vinyl compounds often increases the rate of polymeriza tion and improves the tensile strength and the rate of cure of the final polymers. This allows vulcanization at lower temperature, or with reduced amounts of accelerators and vulcanizing agents. 

Resin and Polymer Solvent. Dimethylacetamide is an exceUent solvent for synthetic and natural resins. It readily dissolves vinyl polymers, acrylates, ceUulose derivatives, styrene polymers, and linear polyesters. Because of its high polarity, DMAC has been found particularly useful as a solvent for polyacrylonitrile, its copolymers, and interpolymers. Copolymers containing at least 85% acrylonitrile dissolve ia DMAC to form solutions suitable for the production of films and yams (9). DMAC is reportedly an exceUent solvent for the copolymers of acrylonitrile and vinyl formate (10), vinylpyridine (11), or aUyl glycidyl ether (12). 

A number of methods such as ultrasonics (137), radiation (138), and chemical techniques (139—141), including the use of polymer radicals, polymer ions, and organometaUic initiators, have been used to prepare acrylonitrile block copolymers (142). Block comonomers include styrene, methyl acrylate, methyl methacrylate, vinyl chloride, vinyl acetate, 4-vinylpyridine, acryUc acid, and -butyl isocyanate. 

AlkyUithium compounds are primarily used as initiators for polymerizations of styrenes and dienes (52). These initiators are too reactive for alkyl methacrylates and vinylpyridines. / -ButyUithium [109-72-8] is used commercially to initiate anionic homopolymerization and copolymerization of butadiene, isoprene, and styrene with linear and branched stmctures. Because of the high degree of association (hexameric), -butyIUthium-initiated polymerizations are often effected at elevated temperatures (>50° C) to increase the rate of initiation relative to propagation and thus to obtain polymers with narrower molecular weight distributions (53). Hydrocarbon solutions of this initiator are quite stable at room temperature for extended periods of time the rate of decomposition per month is 0.06% at 20°C (39). 

Tire Cord. Melamine resins are also used to improve the adhesion of mbber to reinforcing cord in tires. Textile cord is normally coated with a latex dip solution composed of a vinylpyridine—styrene—butadiene latex mbber containing resorcinol—formaldehyde resin.. The dip coat is cured prior to use. The dip coat improves the adhesion of the textile cord to mbber. Further improvement in adhesion is provided by adding resorcinol and hexa(methoxymethyl) melamine [3089-11 -0] (HMMM) to the mbber compound which is in contact with the textile cord. The HMMM resin and resorcinol cross-link during mbber vulcanization and cure to form an interpenetrating polymer within the mbber matrix which strengthens or reinforces the mbber and increases adhesion to the textile cord. Brass-coated steel cord is also widely used in tires for reinforcement. Steel belts and bead wire are common apphcations. Again, HMMM resins and resorcinol [108-46-3] are used in the mbber compound which is in contact with the steel cord to reinforce the mbber and increase the adhesion of the mbber to the steel cord. This use of melamine resins is described in the patent Hterature (49). 

Vinylpyridine (23) came into prominence around 1950 as a component of latex. Butadiene and styrene monomers were used with (23) to make a terpolymer that bonded fabric cords to the mbber matrix of automobile tires (25). More recendy, the abiUty of (23) to act as a Michael acceptor has been exploited in a synthesis of 4-dimethylaminopyridine (DMAP) (24) (26). The sequence consists of a Michael addition of (23) to 4-cyanopyridine (15), replacement of the 4-cyano substituent by dimethylamine (taking advantage of the activation of the cyano group by quatemization of the pyridine ring), and base-cataly2ed dequatemization (retro Michael addition). 4-r)imethyl aminopyri dine is one of the most effective acylation catalysts known (27). 

Synthetic. The main types of elastomeric polymers commercially available in latex form from emulsion polymerization are butadiene—styrene, butadiene—acrylonitrile, and chloroprene (neoprene). There are also a number of specialty latices that contain polymers that are basically variations of the above polymers, eg, those to which a third monomer has been added to provide a polymer that performs a specific function. The most important of these are products that contain either a basic, eg, vinylpyridine, or an acidic monomer, eg, methacrylic acid. These latices are specifically designed for tire cord solutioning, papercoating, and carpet back-sizing. 

In contrast to /3-PCPY, ICPY did not initiate copolymerization of MMA with styrene [39] and AN with styrene [40]. However, it accelerated radical polymerization by increasing the rate of initiation in the former case and decreasing the rate of termination in the latter case. The studies on photocopolymerization of MMA with styrene in the presence of ICPY has also been reported [41], /8-PCPY also initiated radical copolymerization of 4-vinylpyridine with methyl methacrylate [42]. However, the ylide retarded the polymerization of N-vinylpyrrolidone, initiated by AIBN at 60°C in benzene [44]. (See also Table 2.)... 

Zhou L.L. and Eisenberg A., lonomeric blends. II. Compatibility and dynamic mechanical properties of sulfonated cis-l,4-polyisoprenes and styrene/4-vinylpyridine copolymer blends, J. Polym. Sci., Polym. Phy., 21, 595, 1983. 

The most common adhesive system used for bonding continuous fibers and fabrics to rubber is resorcinol-formaldehyde latex (RFL) system. In general, RFL system is a water-based material. Different lattices including nitrile and SBR are used as the latex for the adhesive system. 2-Vinylpyridine-butadiene-styrene is the common latex used in the adhesive recipe. RFL system is widely being used in tires, diaphragms, power transmission belts, hoses, and conveyor belts because of its dynamic properties, adhesion, heat resistance, and the capacity to bond a wide range of fabrics and mbbers. 

Pd(OAc)2 works well with strained double bonds as well as with styrene and its ring-substituted derivatives. Basic substituents cannot be tolerated, however, as the failures with 4-(dimethylamino)styrene, 4-vinylpyridine and 1 -vinylimidazole show. In contrast to Rh2(OAc)4, Pd(OAe)2 causes preferential cyclopropanation of the terminal or less hindered double bond in intermolecular competition experiments. These facts are in agreement with a mechanism in which olefin coordination to the metal is a determining factor but the reluctance or complete failure of Pd(II)-diene complexes to react with diazoesters sheds some doubt on the hypothesis of Pd-olefin-carbene complexes (see Sect. 11). 

If the more activated alkene 2-vinylpyridine is used in place of styrene with the same catalysts and the same range of substrates, anti-Markovnikoff hydroamination is also found. Thus, N-[2-(2 -pyridyl)ethyl]piperidine was isolated in 53% yield from reaction of 2-vinylpyridine with piperidine in the presence of [Rh(COD)2]+/2PPh3 under reflux. N H addition was observed with other amines, the remaining product in all cases being primarily that from oxidative amination (Table 12). When the catalytic reaction was run in the absence of phosphine, the yield of hydroamination product increased dramatically.171... 

Kureshy developed a polymer-based chiral Mn-salen complex (Figure 21). Copolymerization of styrene, divinylbenzene, and 4-vinylpyridine generated highly cross-linked (50%) porous beads loaded with pyridine ligands at 3.8 mmol g-1. Once the polymer was charged with the metal complex catalyst, enantioselective epoxidation of styrene derivatives was achieved with ee values in the range 16 46%. 79... 

The cobalt(II)15 and zinc(II)16 complexes of phthalocyanine(Pc), octcyano-Pc, and tetrasulfon-ato-Pc incorporated in poly(4-vinylpyridine-co-styrene) or Nafion films coated on graphite have also been examined as catalytic devices for dihydrogen electrogeneration in phosphate buffer. These catalytic systems were strongly suggested to be dominated by the electron transfer within the polymer matrix. The best catalytic film is that constituted of the nonsubstituted Con-Pc complex in poly(4-vinylpyridine-co-styrene), giving a turnover number of 2 x 10s h-1 at an applied potential of —0.90 V vs. Ag Ag Cl. 

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