Preparation and characterization of aliphatic/aromatic copolyesters based on bisphenol-A terephthalate, hexylene terephthalate and lactide mioties

To obtain higher molecular weight processable polyesters which are of potential interest for tissue engineering, a series of biodegradable aliphatic/aromatic copolyesters, poly(4,4′-isopropylidenediphenyl terephthalate)-co-poly(hexylene terephthalate)-co-polylactide (PBHTL), were synthesized via direct polycondensation from terephthaloyl dichloride, bisphenol-A, 1,6-hexanediol, and oligolactide. The resulting copolyesters, PBHTL, were characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetry (TG) and wide-angle X-ray scattering (WAXS), and their glass transition temperature (Tg), and thermal decomposition temperature (Td) were obtained. The PBHTL shows two-step thermal decomposition, which is corresponding to segment of 4,4′-isopropylidenediphenyl terephthalate (BAT) and segments of hexylene terephthalate (HT) and lactide (LA), respectively. Due to the incorporation of flexible aliphatic unit into the main chains of copolyesters, PBHTL has lower Tg, and shows enhanced hydrolytic degradability under a physiological conditions with increasing lactide and hexylene moieties. Initial experiments indicated excellent biocompatibility based on cell seeding experiments and microscopic evidence.