Synthesis and characterization of poly(ester ether urethane)s block copolymers based on biodegradable poly(butylene succinate) and Poly(ethylene glycol)

A series of poly(ester ether urethane)s (PEEUs) block copolymers composed of dihydroxy-terminated poly(butylene succinate) (HO-PBS-OH) as the hydrophobic part and poly(ethylene glycol) (PEG) as the hydrophilic part were successfully synthesized and investigated with various PEG mass fraction using isophorone diisocyanate (IPDI) as a chain-extender. Nonisothermal melt-crystallization kinetics and subsequent melting behavior of PEEUs have been investigated by differential scanning calorimetry (DSC). The Avrami equation modified by Jeziorny and Mo's method were applied to describe the kinetics of the crystallization process. Meanwhile, the effects of PEG on the crystalline morphology and crystal structure of PEEUs were studied by wide-angle X-ray diffraction (WAXD), polarized optical microscope (POM). The analysis of nonisothermal crystallization kinetics showed that the crystallization rate of PBS segment within PEEUs was improved by the introduction of high PEG. content. Additionally, banded spherulites were observed regardless of composition for all copolymers. Their biodegradability was investigated by the enzymatic degradation using pseudomonas cepacia lipase. Experimental data showed that biodegradation rate increased with the increasing of PEG content, and a significant rate of degradation was occurred in the PEEU sample with 60 wt% PEG content.