Abstract: Radical copolymerization of vinyl chloride(VC) with N-substituted maleimide were conducted in tetrahydrofuran at 60℃ with AIBN as initiator. Based on the copolymer composition and monomer composition, the copolymerization parameters(r₁, r₂, Q and e) of each monomer pair were determined. The reactivity ratios of N-substituted maleimide monomers were all larger than that of VC, indicating that these monomers were more active. The effects of substituted groups on reactivity ratios were also discussed, and N-substituted maleimide monomer had a larger Q value than that of VC, especially for phenyl substituted maleimide monomer. It was believed that this phenomenon was related to the conjugated effect of phenyl group in N-substituted maleimide. The location of substituent on phenyl would influence Q value of N-substituted phenyl maleimide monomer. para-Substituent(i.e. p-ClPMI and p-MPMI) phenyl maleimide has a large Q value than that of ortho- and meta-substituted phenyl maleimides. In addition, there is a larger difference between e₁ and e₂, which means the large alternating tendency of the copolymerization of N-substituted maleimide with VC. The copolymer compositions for VC/N-substituted maleimide solution copolymerization varied greatly with conversion, especially for small N-substituted maleimide feed ratios. Subsequently, recurrence method deduced from Mayo-Lewis was used for predicting the change of copolymer composition with conversion. In addition, this method is also used to calculate the critical weight [(x_w)_c] conversion for VC/N-substituted maleimide copolymerization systems at different VC monomer feed fractions.

Key words: Vinyl chloride, N-Substituted maleimide, Copolymer composition, Reactivity ratio