Synthesis and characterization of a novel poly(ester‐urethane) containing short lactate sequences and PEG moieties

A novel poly(ester‐urethane) with tailor‐made structure was prepared by using lactic acid (LA) as starting material through a combination of two facile common reactions. First, a diol was prepared via the esterification between LA and poly(ethylene glycol) (PEG) with low molecular weight. Subsequently, the poly(ester‐urethane) was synthesized through the addition polymerization of the LA‐based diol and toluene 2,4‐diisocyanate with 1,4‐butanediol as chain extender. The structure, morphology, and properties of intermediate and the poly(ester‐urethane) were analyzed with Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography (GPC), X‐ray diffraction, differential scanning calorimetry, polarizing optical microscopy, and thermogravimetric analysis. The results indicated that the intermediate was a diol of conjugating quite short lactate sequences with PEG oligomer, and the structure of the poly(ester‐urethane) was as expected. The thermal transition, thermal decomposition temperature, and crystallinity of the polymer samples depended on the molecular size of PEG. In vitro degradation property of the poly(ester‐urethane) also relied on the molecular weight of PEG. The weight loss percentages varied from 11 to 36% after 12‐days immersing in phosphate‐buffer saline at 37°C. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013