Schiff base crosslinked poly(γ-glutamic acid) composite films with high mechanical strength and remoldability

• Dynamic Schiff base crosslinking creates high-performance γ-PGA-based films. • Films exhibit excellent mechanical strength, UV shielding, and solvent resistance. • The films demonstrate outstanding chemical recyclability and reusability. • Promotes γ-PGA-based materials as sustainable alternatives to conventional plastics. With growing concerns over the environmental impact of traditional thermoset materials, the development of green and sustainable alternatives has emerged as a key research priority. In this study, we report a novel approach for fabricating recyclable poly(γ-glutamic acid) (γ-PGA)-based films via dynamic covalent Schiff base crosslinking. γ-PGA was first functionalized with hydrazide groups via reaction with adipic dihydrazide (P-ADH) and subsequently crosslinked with acetoacetylated poly(vinyl alcohol) (AAPVA) under mild, catalyst-free conditions to form an acylhydrazone crosslinked network, resulting in a high-performance, recyclable thermoset film. The resulting films demonstrated excellent mechanical properties (a tensile strength of 123.5 MPa and Young’s modulus of 4.4 GPa), high optical transparency, UV-shielding capability, and solvent resistance. Notably, dynamic crosslinks enable acid-triggered cleavage, allowing for the recovery of macromolecular components and their reprocessing into new films, thereby demonstrating exceptional chemical recyclability and reusability. This work presents a promising strategy for enhancing the performance and sustainability of γ-PGA-based materials and highlights their potential as viable alternatives to conventional plastic thermosets.