Synthesis and Characterization of Some Chitin Co- (acetate/propionate) Copolymers

Chitin, the natural biocompatible and biodegradable polymer consists of β-(1→4) linked 2-acetamido-2-deoxy-Dglucopyranose repeating units, but has limited pharmaceutical and biomedical applications owing to its insolubility in common solvents, although it is the second most abundant natural polymer in the world synthesized by a large number of living organisms. In the present investigation, a series of chitin acetate/propionate copolymers with different content of propionyl and acetyl groups has been synthesized by the esterification of chitin in the presence of perchloric acid as the catalyst using different ratios of acetic and propionic anhydride under heterogenous conditions. Pure chitin diacetate was also synthesized by using the same reaction and their structures were characterized by FTIR and H-NMR spectroscopy. The degree of substitution of propionyl and acetyl groups were 0.05-0.64 and 1.35-1.91, respectively as determined by H-NMR spectroscopy. The expected solubility of these derivatives in common solvents would add new dimensions to their applications in the pharmaceutical and biomedical fields.