Increase in thermal stability of vinyl polymers through radical copolymerization with N ‐cyclohexylmaleimide

It was found that radical polymerization of N ‐cyclohexylmaleimide (CHMI) occurred readily under various polymerization conditions, and that the resulting poly(CHMI) had excellent thermal stability; i.e. the onset of decomposition was 362°C and the maximum rate of decomposition was observed at 430°C by thermogravimetric analysis in nitrogen. Subsequently, radical copolymerizations of CHMI with various vinyl monomers were performed, and the monomer reactivity ratios were determined from the copolymer composition curves obtained. It was found that CHMI copolymerized alternatingly with electron‐donating monomers such as styrene and isobutene. It was also discovered that facile copolymerizations proceeded with methyl acrylate and methyl methacrylate as electron‐accepting monomers, and with vinyl acetate and vinyl chloride as non‐conjugated monomers. It was verified that the introduction of the CHMI unit increased the thermal stability of common vinyl polymers.