Syntheses and Thermostabilities of N-Substituted Maleimide Copolymers. III. N-lsopropylmaleimide, N-sec-Butylmaleimide and N-tert-Butylmaleimide

The objective of this study is to improve the thermostabilities of common vinyl polymers: poly [styrene (ST)] and poly [methyl methacrylate (MMA)], by using, N-substituted maleimide (RMI) [N-substituent (R), R=isopropyl (IPMI), sec-butyl (SBMI), tert-butyl (TBMI)] as a comonomer. IPMI, SBMI and TBMI were copolymerized with ST or MMA in the presence of azobisisobutyronitrile in benzene at 60℃. The thermostabilities of copolymers were investigated by thermal gravimetric (TG) analysis and differential scanning calorimetric (DSC) measurements. Softening points, initial degradation temperatures, and glass transition temperatures of copolymers rose with increasing the contents of RMI in copolymers.