Preparation and characterization of blends of chitosan and tyrosine-derived polycarbonate

Abstract

Chitosan, a saccharide-based biopolymer, exhibites a number of good properties to use as bioactive materials. It was therefore selected to blend with a new class of synthetic polymers, tyrosine-derived polycarbonate (TPC). These polycarbonates contain free carboxyl groups, which can interact with the amino groups on chitosan. Investigation on the interaction between -COOH on TPC and -NH2 on chitosan was carried out by FT-IR analysis. Nevertheless, such electrostatic interaction in the physical blending between the two polymers could not be identified. Amide linkages were therefore introduced in the blends in order to join the two polymers together. The amide formation was not successfully induced by heat treatment, without causing color change in the blends. A coupling agent, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDCI) was therefore used to form amide bonds between the two polymers and the results show 1555 cm-1. In addition, chitosan was coated on the TPC film. The physical coating of chitosan on TPC did not yield tightly-bound chitosan layer. A coupling agent, EDCI was again used to join the two polymer layers by amide linkages. Analyses of polymer blends with and without EDCI, and chitosan coated TPC with EDCI, were carried out by tensile testing, scanning electron microscopy (SEM) and Ca2+ adsorption study.