Macromolecular engineering of self-standing chitin/montmorillonite nanocomposite films with enhanced mechanical, thermal, antimicrobial, and antibiofilm performance

Abstract

Self-standing polymer films require improved mechanical strength, thermal stability, and resistance to microbial growth for practical coating and barrier applications. This study developed self-standing chitin/montmorillonite (MMT) nanocomposite films with enhanced mechanical, thermal, and antimicrobial properties. Chitin/MMT films (0–15 wt% MMT) were fabricated via a low-temperature NaOH/urea system and ethanol coagulation, followed by cation-exchange intercalation of benzyldimethylstearylammonium chloride (C18-BAC). Comprehensive structural characterizations, including XRD, FTIR, and FESEM, confirmed the successful intercalation of C18-BAC and uniform MMT dispersion at optimal loadings. The 3 wt% MMT composites exhibited the highest tensile strength (42.3 MPa, a 10.5 % improvement) while maintaining >80 % optical transparency. Thermal stability progressively increased with MMT content. Crucially, antimicrobial assays demonstrated a predominantly non-leaching, contact-active mechanism against Staphylococcus aureus , Bacillus subtilis , and Escherichia coli , overcoming the limitations of diffusion-based release. The optimized 3 wt% formulation significantly reduced biofilm biomass by 68.4 % for B. subtilis , 65.2 % for S. aureus , and 54.1 % for E. coli relative to controls. These findings highlight that controlled MMT incorporation and C18-BAC intercalation effectively tune the macromolecular architecture of chitin films. The developed system offers a sustainable, non-leaching antimicrobial coating with strong potential for active food packaging applications.