Synthesis, characterization, and enzymatic degradation of network aliphatic copolyesters

Network copolyesters were prepared from glycerol (Yg) and sebacic acid (10) with 10-90 mol % of either succinic acid (4), 1,12-dodecanedicarboxylic ac id (14), 1,18-octadecanedicarboxylic acid (20), or terephthalic acid (T). P repolymers prepared by melt-polycondensation were cast from dimethylformami de solution and postpolymerized at 230-250 degrees C for various periods of time to form a network. The resultant films were transparent, flexible, an d insoluble in organic solvents. The network copolyesters obtained were cha racterized by infrared absorption spectra, wide angle X-ray diffraction ana lysis, density measurement, thermomechanical analysis, differential scannin g calorimetry, and tensile test. The enzymatic degradation was estimated by weight loss of the network copolyester films in a buffer solution with Rhi zopus delemar lipase at 37 degrees C. The weight loss due to the enzymatic degradation was decreased with increasing comonomer content, and the copoly esters with Yg4, Yg20 and YgT more than 50 mol % were not degraded by lipas e enzyme at all. On the contrary, Yg-10/14 films were degraded appreciably over whole range of comonomer composition. With increasing comonomer conten t, the heat distortion temperature increased gradually, while the tensile s trength and Young's modulus were not changed much. (C) 1999 John Wiley & So ns, Inc.