Systematic Study of Thermal and (Bio)Degradable Properties of Semiaromatic Copolyesters Based on Naturally Occurring Isosorbide

Here we present a series of copolyesters of poly(butylene terephthalate) (PBT) with the renewable building block isosorbide (1,4:3,6-dianhydro-d-glucitol, IS), designated PBIT. The aim of this work is to systematically elucidate how the inherent properties (reactivity, structural asymmetry, structural rigidity, and hydrophilicity) of IS would affect the synthesis and thermal/(bio)degradable performance of PBIT copolyesters. The target copolyesters containing 0–50 mol % IS units were successfully synthesized by melt polycondensation and were afforded in fully random microsequential structures. Their number-average molecular weights and intrinsic viscosities are in the ranges of 22 400–31 000 g/mol and 0.5–0.65 dL/g, respectively. The thermal properties determined by differential scanning calorimetric analysis firmly confirmed the remarkable Tg-enhancing effect of IS. Comprehensive degradation study further revealed that IS incorporation promotes remarkable hydrolytic degradation in a relatively harsh acidi...