Abstract: PBS was modified by diol and diacid separately forming two copolyesters, PBSH and PBSA, which were introduced into phosphate buffer as substrates with lipase N435 for investigating the degradation behavior. Gel permeation chromatography, thermogravimetric analysis, and wide-angle X-ray diffraction were employed to investigate the change in the molecular mass, thermal properties, and crystallinity of the copolymer before and after enzymatic degradation. Polarized optical microscopy was employed to investigate the surface morphology of the copolymers. It indicated that the sensitivity of PBSA and PBSH to lipase was significantly improved with degradation rates after 24 h greater than 90 % and 60 %, respectively. The degradation rate of PBSA was significantly higher than that of PBSH. The number-average molecular weight of the two copolymers changed marginally, but the molecular weight distribution became wider, and crystallinity increased. The thermal stability of PBSA decreased, while the thermal stability of PBSH improved after 3 days. The results obtained from the molecular enzymesubstrate binding model were in agreement with experimental results.

Key words: lipase, poly(butylene succinate)-based copolymer, enzymatic degradation, molecular simulation