Structure-Biodegradability Relationship of Polyesters

Abstract

The biodegradability of polymers and also polyesters is solely determined by the structure and the morphology of the plastics. To ensure environmental safety of products and to be able to design new tailor made biodegradable plastics, it is important to know the correlation of structure and biodegradability. Based on especially synthesised aliphatic polyesters, aromatic polyesters, aliphatic-aromatic copolyesters and low molecular weight oligo-esters we studied the degradation behaviour with a lipase from Pseudomonas sp. For aliphatic polyesters the difference between melting temperature of the polymer and the degradation temperature turned out to be predominantly determining the degradation. The missing degradability of aromatic polyesters is obviously not caused by a steric hindrance of the polymer — enzyme complex but must be correlated with the high melting point and also the low flexibility of the polymer chains. The degradability of aliphatic-aromatic copolyesters is not determined by the number of aliphatic ester bonds and the length of aliphatic sequences, but the length of aromatic domains. The length of these domains correlates with the melting temperature of the materials.