Aliphatic–aromatic poly(butylene carbonate‐co‐terephthalate) random copolymers: Synthesis, cocrystallization, and composition‐dependent properties

ABSTRACT A series of aliphatic–aromatic poly(carbonate‐ co ‐ester)s poly(butylene carbonate‐ co ‐terephthalate)s (PBCTs), with weight‐average molecular weight of 113,000 to 146,000 g/mol, were synthesized from dimethyl carbonate, dimethyl terephthalate, and 1,4‐butanediol via a two‐step polycondensation process using tetrabutyl titanate as the catalyst. The PBCTs, being statistically random copolymers, show a single T g over the entire composition range. The thermal stability of PBCTs strongly depends on the molar composition. Melting temperatures vary from 113 to 213°C for copolymers with butylene terephthalate (BT) unit content higher than 40 mol %. The copolymers have a eutectic melting point when about 10 mol % BT units are included. Crystal lattice structure shifts from the poly(butylene carbonate) to the poly(butylene terephthalate) type crystal phase with increasing BT unit content. DSC and WAXD results indicate that the PBCT copolymers show isodimorphic cocrystallization. The tensile modulus and strength decrease first and then increase according to copolymer composition. The enzymatic degradation of the PBCT copolymers was also studied. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 41952.