Reaction, chain, copolymer examples

Amines can also swell the polymer, lea ding to very rapid reactions. Pyridine, for example, would be a fairly good solvent for a VDC copolymer if it did not attack the polymer chemically. However, when pyridine is part of a solvent mixture that does not dissolve the polymer, pyridine does not penetrate into the polymer phase (108). Studies of single crystals indicate that pyridine removes hydrogen chloride only from the surface. Kinetic studies and product characterizations suggest that the reaction of two units in each chain-fold can easily take place further reaction is greatiy retarded either by the inabiUty of pyridine to diffuse into the crystal or by steric factors. 

Copolymerisation is a polymerisation reaction in which a mixture of more than one monomeric species is allowed to polymerise and form a copolymer. The copolymer can be made not only by chain growth polymerisation but by step growth polymerisation also. It contains multiple units of each monomer used in the same polymeric chain. For example, a mixture of 1, 3 - butadiene and styrene can form a copolymer. 

Polymers containing azo groups as part of their backbone chain can be used for the synthesis of block copolymers. The azo-containing prepolymers can, for example, be synthesised by condensing small molecule azo compounds with functionalized polymers, by partial decomposition of polymeric azo compounds in the presence of a monomer or via polymer analogue reactions. Block copolymers are obtained when those prepolymers are decomposed in the presence of another monomer. 

Both addition and condensation polymerization can be carried out with mixtures of two or more types of monomers present in the reaction mixture. The result is a random copolymer that incorporates both types of monomers in an irregular sequence along the chain. For example, a 1 6 molar ratio of styrene to butadiene monomers is used to make styrene-butadiene rubber (SBR) for automobile tires, and a 2 1 ratio gives a copolymer that is an ingredient in latex paints. 

It is important to point out that the quantum yield for the Norrish II chain scission reaction ( Cs) is highly affected by the mobility of polymer chains. For example, the photolysis CS for a film of the copolymer poly(styrene-co-phenyl vinyl ketone) irradiated at 313 nm in the solid state was shown to be low (0.04—0.09) at temperatures below the copolymer Tg (glass transition temperature) but increased dramatically at,... 

Polymerization of ROZI monomers behaved in almost all cases similarly to ROZO monomers in many respects, except for the product polymer structures with a trimethylenimine chain of PROZI instead of an FI chain of PROZO. Many similar behaviors in both monomers of ROZI and ROZO include a living character of CROP, various copolymer syntheses, DIP, and an M monomer in zwitterionic alternating copolymerizations. It may be important to mention, however, that ROZI is a little more basic than ROZO from the initiation reaction studies for example, pKa value for iPrOZI and iPrOZO are 7.1 and 5.4 in water at 25 °C, respectively. 

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). 

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