SYNTHESIS, CHARACTERIZATION, AND ENZYMATIC DEGRADATION OF NOVEL REGULAR NETWORK ALIPHATIC POLYESTERS BASED ON PENTAERYTHRITOL

Novel regular network polyesters were prepared from pentaerythritol (X p) 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). P repolymer prepared by melt polycondensation was cast from dimethylform amide 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 c haracterized by infrared absorption spectra, nide angle X-ray diffract ion analysis, density, thermomechanical analysis, differential scannin g calorimetry, tensile test, water absorption, and alkali hydrolysis. The enzymatic degradation estimated by weight loss of the network poly ester films in a buffer solution of various kinds of lipases at 37 deg rees C was studied. The enzymatic degradation of Xpn films was compare d with that of the network polyester films of glycerol with various al iphatic dicarboxylic acids reported earlier.(12) After a 6 day incubat ion in Rhizopus delemar lipase solution, the weight loss was hardly ob served for Xp4-8, while it increased gradually for Xp9-14 and showed t he maximum weight loss of 13 g/m(2) for Xp14; then the weight loss dec reased abruptly for Xp16-20. Other lipases of porcine pancreas and Can dida rugosa hardly degraded Xpn films.