Radiation‐induced solid‐state copolymerization of maleic anhydride and acenaphthylene

Radiation‐induced solid‐state copolymerization of the maleic anhydride–acenaphthylene system was carried out for the purpose of studying the solid‐state polymerization of vinyl compounds in a binary system. Melting point measurement confirmed that this binary monomer system forms a eutectic mixture in the solid state. The solid‐state polymerization of these monomers proceeds at maximum rate at the eutectic composition, and the polymerization products consist of a mixture of polyacenaphthylene and 1:1 maleic anhydride–acenaphthylene alternating copolymer. Since the 1:1 copolymer was obtained in solution polymerization also and maleic anhydride did not homopolymerize in solid state, it is considered that the solid‐state copolymerization of maleic anhydride and acenaphthylene occurs in a liquidlike state at the boundary of the two monomer crystals.