Copolymers alternating copolymers

Analogously to ethylene-carbon monoxide copolymers, alternating copolymers between cycloolefins such as norbornene and carbon monoxide have been synthesised using cationic Pd(II) complexes modified by phosphorus ligands such as [Pd(MeCN)n(PPh)4 J[BF4]2( = 1,2,3) [27]. General requirements for the... 

Random Copolymers Alternating Copolymers Graft Polymers Block Copolymers... 

A polymer resulting from polymerisation of two or more different monomers i.e., ter-polymer, tetra-polymer for two- and three monomers, respectively. (see also RANDON COPOLYMER, ALTERNATING COPOLYMER, GRAFT COPOLYMER, BLOCK COPOLYMER.)... 

A large portion of all styrene polymers produced commercially are copolymers. Therefore, the understanding of the Q-e schemeof Alliey and Price (18,19) is important in designing copolymers for specific end uses. The Q-e scheme is a way to correlate structure and reactivity of comonomers. In Equations 2 and 3, Q, and Qj are measures of the resonance stabilization of M, radical and Mj monomer, respectively. The terms e, and e represent measures of the polar properties of the comonomers. In Table 5, styrene s Q-e values are Q=-0.80 and e=l. 00. By selecting comonomers with proper Q-e values, copolymerizations of styrene can give random copolymers, alternating copolymers, or block copolymers. 

The traditional linear copolymers can be divided into three categories, that is, random copolymers, alternating copolymers, and statistical copolymers. The first two categories can be seen... 

While most copolymers of vinyl acetate are random copolymers, alternating copolymers are formed when the reactivity ratios for the two monomers are suitable. This occurs spontaneously when vinyl acetate is polymerized with electron-poor monomers such as maleic anhydride [273]. Alternatively, it has been reported that acrylonitrile which has been precomplexed with zinc chloride gives alternating polymers with vinyl acetate [274]. Block polymers of vinyl acetate with methyl methacrylate, acrylonitrile, acrylic acid, and n-vinyl pyrrolidone have been prepared by the strategy of preparing poly(vinyl acetate) macroradicals in poor solvents in which the macroradicals are occluded. Addition of a second monomer swells the polymer coils, and polymerization continues with the addition of the new monomer [275]. 

A homopolymer consists of only one type of constitutional repeating unit (A). A copolymer, on the other hand, consists of two or more constitutional repeating units (A, B, etc). Several classes of copolymer are possible block copolymers, alternating copolymers, graft copolymers and statistical copolymers (Fig. 1.10). 

Random copolymer Alternating copolymer Diblock copolymer Triblock copolymer Pentablock copolymer Terpolymer AABBBABBAAAB ABABABABABAB AAAABBBBBBB AAAABBBBBAAAA AAABBBBAAABBBBAAAA AABBCCCBBAABBCCCAAA... 

Random Copolymer Alternating Copolymer Block Copolymer ... 

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