Sequence-Controlled Radical Polymerization of N-Substituted Maleimides with 1-Methylenebenzocycloalkanes and the Characterization of the Obtained Copolymers with Excellent Thermal Resistance and Transparency

The radical copolymerization of N-methyl, ethyl, n-butyl, and 2-ethylhexylmaleimides (RMIs) with 1-methylenebenzocycloalkanes (BCms) was carried out to fabricate thermally stable and transparent polymer materials. The copolymerization reactivity of BCms significantly depended on the carbon number of the ring structure of BCms. The analyses of the comonomer-copolymer composition curves and theoretical calculations results revealed that the sequence-controlled copolymerization of RMIs with BCms occurred in alternating and 2:1 fashions according to the BCms reactivity, which depends on the coplanarity of the exomethylene moiety and the benzene ring. The alternating and high-molecular-weight copolymers of BCms and RMIs exhibited excellent thermal and optical properties. We have demonstrated that the radical copolymerization of RMIs is useful not only as the method for high-performance transparent polymer production but also as the tool for the fundamental research of radical polymerization mechanism.