HYDROLYTICALLY DEGRADABLE AMINO-ACID CONTAINING POLYMERS

A universal approach to incorporate amino acids into a polymeric backbone via hydrolytically labile bonds is reported. The amino acids were first converted into dicarboxylic acids by derivatization at their amino terminus with trimellitic anhydride and subsequently polymerized via the corresponding mixed anhydride by melt polycondensation in vacuo at elevated temperatures (100-200 °C). The reaction conditions (e.g., reaction time, temperature, and effect of several catalysts) were optimized for both the homopolymers and copolymers with sebacic acid in defined ratios. Polymerizations performed at 180 °C gave, in general, maximal molecular weight after 1-2 h, followed by subsequent gelation of the polymers. Higher molecular weight copolymers (Mw >100000) were obtained with increasing content of sebacic acid, which exhibited low melting points (<100 °C) and good solubility in common organic solvents. Both enhanced degradation (as compared to conventional poly(amino acids)) due to the presence of hydrolytically labile anhydride bonds and improved mechanical strength as a result of the existing imide bonds was observed. © 1990, American Chemical Society. All rights reserved.