Aliphatic‐aromatic copolycarbonates derived from 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol

The synthesis of copolycarbonates with high aliphatic contents for possible applications as optical plastics is described. Copolymers of 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol (TMCBD) with a series of 14 bisphenol derivatives were prepared and characterized. The refractive index of these materials varies from 1.49 for the 2,2‐hexafluoropropane substituted copolymer to 1.57 for the 9,9‐fluorene substituted copolymer; thus, all of the copolymers exhibit lower refractive indices than the bisphenol A homopolycarbonate. The glass tran‐sition temperatures of the copolymers vary from 110 to 210°C; the beta transition tem‐peratures vary from ‐70 to 0°C when measured at 10 Hz by dynamic mechanical analysis. The copolymers exhibited good thermal stability (0–3% weight loss) when heated above the glass transition temperature, and only undergo extensive decomposition (80–90%) at 300–360°C.