Interfacial engineering of poly (lactic acid) composite films using esterified cellulose nanocrystals/curcumin hybrid nanofiller for improved mechanical and antibacterial performance

Polylactic acid (PLA), as a biodegradable material, is considered an ideal alternative to petroleum-based plastics. The intrinsic mechanical fragility and lack of multifunctional characteristics significantly constrain its practical utilization in advanced applications. This study designed and prepared a ternary PLA composite material with uniform surface and enhanced functionality by uniformly dispersing esterified CNC (E n CNC) Curcumin (Cur) hybrid nanostructures in the polymer matrix. The synergistic interaction between the E n CNC and Cur significantly enhanced their interfacial compatibility with the PLA matrix, leading to uniform dispersion and significantly improved flexibility. The flexibility of resulting E n CNC_Cur_PLA composite films was significantly improved, with elongation at break increased to 64.42 %, representing a 628.59 % increase compared to pure PLA. The addition of EnCNC increased the bioavailability of Cur and demonstrated multifunctional effects, including controlled release of Cur in ethanol, enhanced antioxidant activity (80.6 % DPPH clearance) and antibacterial activity (over 99 % against Escherichia coli, 87.7 % against Staphylococcus aureus ). Overall, these results highlight a simple and effective strategy to fabricate multifunctional, sustainable bio-based films with improved mechanical performance and biological activity, suitable for advanced food packaging applications.