Facile Preparation of Graphene Oxide-Enhanced Highly Crystalline Polyglycolic Acid Under Low-Temperature Crystallization Using Tin(II) 2-Ethylhexanoate and Its Application in Biomaterials

Polyglycolic acid (PGA), a biodegradable polymer with many potential applications, is primarily synthesized via the ring-opening polymerization of glycolide monomers. Here, the temperature sensitivity of the PGA crystallization kinetics is systematically analyzed using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). Regression analysis yields Avrami exponents (<i>n</i>) within the range 1.41-1.51, indicating that PGA forms lamellar crystals during crystallization from heterogeneous nucleation. The FTIR indicates that the PGA molecular chains alter their conformation during crystallization. XRD reveals that the crystallization rate and crystallinity of PGA closely correlate with the processing temperature. The heterogeneous nucleation of PGA can be optimized by incorporating suitable nucleating agents or regulating the surface roughness to improve the crystallization rate and quality. Polarized optical microscopy (POM) indicates that elevated temperatures increase the polymer chain mobility and free growth of crystallization nuclei, whereas lower temperatures promote the rapid formation of crystallization nuclei but impede growth. Graphene oxide (GO) has abundant surface functional groups, is an efficient heterogeneous nucleating agent, and promotes molecular chain alignment to increase both the crystallization rate and crystallinity. This GO-induced enhancement demonstrates a promising strategy for tailoring the thermal and mechanical properties of PGA for advanced biomedical applications.