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

Abstract

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.