Influence of carboxylic acid content and polymerization catalyst on hydrolytic degradation behavior of Poly(glycolic acid) fibers

Abstract

Poly(glycolic acid) (PGA) is an aliphatic polyester with the simplest chemical structure. Since PGA is susceptible to hydrolysis, various researchers studied the factors affecting the hydrolytic degradation behavior of PGA. The factors include the higher-order structure, pH, ionic electrolyte etc. In this study, to clarify the mechanism for the hydrolysis of PGA fibers, effect of the carboxylic acid content on the hydrolytic degradation behavior was investigated through the quantitative evaluation of the amounts of the carboxylic acid end group and the PGA monomer (glycolide, GL) in the fibers. Evaluation of the hydrolysis of PGA fibers through the analyses of the molecular weight retention and tensile strength retention after immersing in the phosphate buffer solution at 37 °C revealed that the hydrolysis is governed by the carboxylic acid content in the PGA fibers. It was also found that the amount of GL generated during the melt spinning process is affected by the amount and type of polymerization catalyst. In addition, the experimental results of fundamental analysis suggested that the polymerization catalyst also decomposes the GL into glycolic acid or glycolic acid dimers to generate carboxylic acid, and the rate of decomposition varies depending on the type and amount of catalyst. Based on these results, it was concluded that there is an indirect effect of the type and amount of polymerizing catalyst on the rate of hydrolysis of PGA fibers.