Acceleration Effects of Residual Monomers on the Degradation of Poly(glycolic acids)

The degradation rate of biodegradable materials, which may be affected by many factors, is often the focus of research aimed at expanding its application. During the fabrication of polyglycolide (PGA), glycolide (GA) monomers are often difficult to be completely polymerized and eliminated. The residual monomer may influence the degradation rate of the obtained PGA resin. In this study, the effect of the presence of GA monomer on the degradation behavior of PGA in three different solutions was investigated, and the chemical structure change, weight loss, crystallinity, intrinsic viscosity, thermal performance, and microscale morphology within 2 weeks were characterized. The results showed that the mass loss rate, crystallinity and intrinsic viscosity of PGA depended on the GA content and the degradation environment. Furthermore, different degradation solutions were found to result in varied degradation rates of PGA. Generally, the degradation rate of PGA in NaOH solution was the fastest, followed by HCl solution, and the slowest degradation was observed in deionized water. However, regardless of the type of solution used, it could be concluded that the GA monomer accelerated the degradation of PGA. The effect of GA on the degradation of PGA was attributed to the increase in the hydrophilicity of the polyester when GA was present, leading to a microporous structure of the material, which accelerated the degradation of the material by internalized water molecules.