Synthesis and Properties of Biodegradable Poly(butylene succinate-co-diethylene glycol succinate) Copolymers

Diethylene glycol was incorporated into poly(butylene succinate) (PBS) to form biodegradable poly(butylene succinate-co-diethylene glycol succinate) (P(BS-co-DEGS)) copolymer through a two-step procedure of esterification and polycondensation from succinic acid with 1,4-butanediol and diethylene glycol. The chemical structure of P(BS-co-DEGS) was confirmed by proton nuclear magnetic resonance spectroscopy (H-1 NMR). The effect of incorporated DEGS content on the molecular weight, thermal properties, crystallization behaviors, and hydrophilicity of the copolymers was investigated by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), thermogravimetry analysis (TGA), and water contact angle. The mechanical properties and hydrolytic degradation behaviors of P(BS-co-DEGS) were also studied. The results suggest that with an increase of DEGS content, the crystallizability and degree of crystallinity of the copolymers decreased, while the crystal structure kept unchanged; the thermal stability of the copolymers hardly changed, while the hydrophilicity and hydrolytic degradation rate increased. The tensile modulus decreased, but the elongation at break increased and the tensile strength increased first and then decreased with an increase of DEGS.