Enhancing degradation resistance of polyglycolic acid through stereocomplex polylactic acid integration: A novel “stereo-lock” approach

Abstract

The increasing concerns over pollution from non-degradable plastics are prompting a quest for sustainable alternatives. Polyglycolic acid (PGA), known for its good biocompatibility and high mechanical strength, faces limited applications due to its uncontrollable degradation rate. This article introduces an effective approach to enhance the shelf life of PGA by constructing a novel “stereo-lock” structure. Stereocomplex polylactic acid (ScPLA) is first disassembled and fixed to the amorphous region of PGA by melt spinning. Later, an annealing process enhances molecular chain mobility, leading to the reformation of ScPLA and the locking of entangled PGA amorphous molecular chains, resulting in the formation of “stereo-lock” configurations. Thus, molecular chain density in the amorphous area increases, which reduces the accessibility of water to ester bonds and is conducive to improving the degradation resistance of PGA. As a result, compared to pure PGA, the rate of degradation of the monofilament possessing “stereo-lock” structure is noticeably slower. Specifically, by the seventh day of the accelerated degradation tests, the weight loss of the PGA monofilament dropped from 61.4 % to 48.4 % in the monofilament with “stereo-lock”. Furthermore, the formation mechanism of the “stereo-lock” was confirmed through a series of investigations and analyses. The structure-property relationship between molecular chain entanglement and degradation properties of PGA was studied systematically in this study, which also offers fresh perspectives on how to control the degradation characteristics of other polymers.