Vinyl ethers chain transfer constants

As model compounds, we used isopropyl p-nitrobenzoate for poly(vinyl p-nitrobenzoate), p-nitrophenyl iaobutyrate for poly(p-nitrophenyl acrylate), p-nitrocumene for poly(p-nitrostyrene), and p-nitrophenyl isopropyl ether for poly(p-nitrophenyl vinyl ether). The structure and Hammett s a constants of these model compounds and the chain transfer constants of polystyrene radicals to these compounds are given in Table 5 (3). 

VEs do not readily enter into copolymerization by simple cationic polymerization techniques instead, they can be mixed randomly or in blocks with the aid of living polymerization methods. This is on account of the differences in reactivity, resulting in significant rate differentials. Consequendy, reactivity ratios must be taken into account if random copolymers, instead of mixtures of homopolymers, are to be obtained by standard cationic polymeriza tion (50,51). Table 5 illustrates this situation for butyl vinyl ether (BVE) copolymerized with other VEs. The rate constants of polymerization (kp) can differ by one or two orders of magnitude, resulting in homopolymerization of each monomer or incorporation of the faster monomer, followed by the slower (assuming no chain transfer). 

MA-styrene copolymerization, 274 MA-vinyl chloride copolymerization, 274 Chain transfer reactions, MA copolymerization, 282, 308, 329, 331, 390, 396, 407 Charge-transfer complexes AIBN-MA pair, 298 detection methods, 208-210 in Diels-Alder reaction, 140 difluoromaleic anhydride with styrene, 394 difluoromaleic anhydride with vinyl ethers, 394 ene reaction intermediate, 168 equilibrium constants, 332, 390-402, 409, 411, 415-417, 454... 

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