Constructing highly oriented β form represents a promising strategy to address the inherent high density and brittleness of biodegradable poly(glycolic acid) (PGA). In this work, we fabricated PGA with different entanglement densities via melt blending with epoxy-functional copolymer, thereby proposing a novel strategy for achieving high-content oriented β form through the synergistic regulation of chain entanglement and an extensional strain. The high chain mobility characteristic of low entanglement density PGA (378 mol/m3) enhances chain orientation, it causes a significant reduction in chain mobility, thereby restricting crystal growth and decreasing overall crystallinity. Notably, the excessive chain orientation induces a form transition from the helical conformation of β form to the more extended conformations characteristic of α form. This work provides valuable insights into the relationships between entanglement density, orientation, and polymorphic crystallization of PGA materials, with potential applicability to other semicrystalline polymer systems.
Wang et al. (2026) studied this question.