Synthesis, characterization, and enzymatic degradation of novel regular network aliphatic polyesters based on pentaerythritol

Novel regular network polyesters were prepared from pentaerythritol (Xp) and aliphatic dicarboxylic acids of different numbers of methylene groups (HOOC(CH2)(n)-2COOH, n = 4, 6, 8, 9, 10, 12, 14, 16, and 20). Prepolymer prepared by melt polycondensation was cast from dimethylformamide solution and postpolymerized at 270 degrees C for various times to form a network. The resultant films were transparent, flexible, and insoluble in organic solvents. The network polyesters obtained were characterized by infrared absorption spectra, nide angle X-ray diffraction analysis, density, thermomechanical analysis, differential scanning calorimetry, tensile test, water absorption, and alkali hydrolysis. The enzymatic degradation estimated by weight loss of the network polyester films in a buffer solution of various kinds of lipases at 37 degrees C was studied. The enzymatic degradation of Xpn films was compared with that of the network polyester films of glycerol with various aliphatic dicarboxylic acids reported earlier.(12) After a 6 day incubation in Rhizopus delemar lipase solution, the weight loss was hardly observed for Xp4-8, while it increased gradually for Xp9-14 and showed the maximum weight loss of 13 g/m(2) for Xp14; then the weight loss decreased abruptly for Xp16-20. Other lipases of porcine pancreas and Candida rugosa hardly degraded Xpn films.