POLYMERIZATION AND COPOLYMERIZATION OF METHYL 2-(CHLOROMETHYL)ACRYLATE IN COMPETITION WITH ADDITION FRAGMENTATION

Polymerization and copolymerization of methyl 2-(chloromethyl)acrylate (MCMA) to low molecular weight with accompanying beta-fragmentation of the MCMA radical leading to the 2-carbomethoxyallyl end group were investigated. The H-1 NMR spectrum of poly(MCMA) revealed that the fragmentation is predominant as the chain-stopping process when M(n)BAR = 4400. In this case, the fragmentation occurred every 33 propagation steps on average, and the ratio of the rate constants for propagation to fragmentation was estimated to be 11 L/mol at 60-degrees-C. The copolymerization of MCMA with methyl methacrylate (MMA) gave copolymer with unsaturated end groups adjacent to MCMA and MMA units as observed by H-1 NMR spectroscopy. The contents of MCMA and MMA units bound to the unsaturated end group depend on the comonomer composition and the monomer reactivity ratio. The relative reactivities of poly(MCMA) and poly(MMA) radicals toward MCMA were determined from the comonomer-copolymer composition relation and the amount of the different monomer units linked to the unsaturated end group. The effect of the adjacent units on fragmentation was considered in relation to the content of the unsaturated end group relative to the MCMA units comprising the main chain. Fragmentation was facilitated more than propagation by raising the temperature.