Free-radical-initiated copolymerization of 2-chlorostyrene, 4-chlorostyrene, and 2,6-dichlorostyrene with maleic anhydride

The title copolymers have been prepared by the free-radical-initiated copol ymerization of 2-chlorostyrene (2-ClSt), 4-chlorostyrene (4-ClSt) and 2,6-d ichlorostyrene (2,6-DClSt) with maleic anhydride (MAn) in toluene at 65 deg reesC. Copolymers of chlorinated styrenes with MAn prepared under different monomer-to-monomer ratios in the feed have alternating composition. In all cases, the mixture of comonomers forms charge-transfer complex monomers (C TC). The initial rate of copolymerization increases with the increase of el ectron donors in the comonomer feed and the highest rates were at the equim olar ratios of comonomers in the feed. The thermal stability of the polymer s was measured by thermogravimetric analysis in nitrogen. Homopolymers deco mpose by a one-step mechanism, while copolymers are more thermostable and d ecompose by a two-step mechanism. Glass transition temperatures (T(g)s) of homopolymers are lower than T(g)s of copolymers. The number and weight aver age molecular weights of chlorinated copolymers are higher than those of th e corresponding homopolymers.