Reactive Compatibilization of Polyglycolic Acid/Polyurethane Blends for an Improved Strength-Toughness Balance

Polyglycolic acid (PGA) possesses superior mechanical strength but suffers from inherent brittleness, which severely limits its application scope. In this work, we synthesized a high-toughness poly(ε-caprolactone)-based thermoplastic polyurethane (TPU) to toughen PGA, employing a multifunctional epoxy chain extender (ADR) as a reactive compatibilizer. Melt blending PGA with TPU successfully induced a brittle-to-ductile transition, evolving the phase morphology from a sea-island structure to a co-continuous architecture. While the binary PGA/TPU blend achieved a remarkable notched impact strength of 21.7 kJ m^-2 (approximately 7.5 times that of neat PGA), the weak interfacial adhesion resulted in a drastic sacrifice of tensile strength, which plummeted from 131.9 MPa to 37.1 MPa. To overcome this trade-off, ADR was introduced to promote chain extension, branching, and enhanced interfacial interactions during melt blending. Consequently, the representative blend achieved an improved strength-toughness balance, exhibiting a tensile strength of 75.1 MPa and a robust notched impact strength of 16.9 kJ m^-2. The combination of high mechanical strength and enhanced impact resistance endows the developed PGA-based blends with considerable potential for advanced load-bearing and impact-resistant polymer components. In particular, these characteristics may enable their use in emerging applications such as compliant structural components, protective elements, and mechanically robust parts for biomimetic robotic systems.