Synthesis and Enzymatic Degradation of Aliphatic Polyesters Copolymerized with Trimesic Acid

Abstract

Network copolyesters were made from adipic acid and ethylene glycol with 10-40 mol% trimesic acid (Y). Prepolymers prepared by melt polycondensation were cast from dimethylformamide solution and postpolymerized at 26OOC for various times to form a network. The degree of reaction (&), estimated from the infrared absorbance of hydroxyl and methylene groups, increased with increasing postpolymerization time and leveled out at about 90% after 4-6 hours. Heat distortion temperatures (TJ measured by thermomechanical analysis increased greatly from -83 to 48OC upon the incorporation of Y. Wide-angle x-ray diffraction patterns showed that the copolymer films are amorphous. Density, tensile strength, and Young's modulus decreased for the copolymers with 10-30 mol% Y, whereas they increased drastically for the copolymer with 40 mol% Y. The enzymatic degradation was esti-965 Copyright 0 1997 by Marcel Dekker, Inc. Downloaded by [The University of Manchester Library] at 05:35 13 October 2014 966 NAGATA ET AL.mated by the weight loss of the copolymer films in buffer solutions with a lipase at 37OC. The weight loss decreased remarkably with increasing Y and showed no weight loss for the copolymer with 40 mol% Y. On the other hand, the weight loss by alkali hydrolysis increased for the copolymers with 10 and 20 mol% Y, implying a difference in the degradation mechanism between enzymatic degradation and alkali hydrolysis.

Synthesis of branched poly(butylene succinate): Structure properties relationship

“…Branched poly(butylene adipate)s were also synthetized using pentaerythritol (f = 4) or glycerol [7] . A multifunctional acid, trimesic acid (f = 3) may also be used [8] .…”

“…By contrast, long branches enhance melt viscosity, shear thinning and extension thickening which is desirable for processing. Moreover, the presence of a branching agent could modulate the biodegradability of the polymer [8,15] .…”