Copolymerization of 4‐cyclopentene‐1,3‐dione with styrene

The copolymerization of 4‐cyclopentene‐1,3‐dione (D) with styrene (S) is reported. The copolymers were prepared by heating sealed tubes containing the monomer feeds and azobisisobutyronitrile. The copolymers exhibited infrared bands for the phenyl and β‐diketone groups, indicating that copolymerization had occurred. The copolymers were completely insoluble in all solvents. Some swelling was observed in tetrahydrofuran, nitrobenzene, and aqueous sodium hydroxide. From the compositions of the copolymers, as determined from the carbon and hydrogen analyses, it was found that the copolymers were about 40 mole‐% styrene over an appreciable range of feed compositions (0.1–0.6 mole fraction styrene). The results at styrene feeds