Polyvinyl Alcohol/Chitosan-Ethyl Lauroyl Arginate Bilayer Films with Dual Surfaces: Improved Physicochemical Properties and Antimicrobial Properties.

In this study, polyvinyl alcohol (PVA) and chitosan (CS) were used as the base materials, and ethyl lauroyl arginate (LAE) as the antibacterial agent to prepare biodegradable bilayer composite films (P/C-L), whose properties compared with those of the monolayer films (P-C-L) of identical composition. Scanning electron microscopy (SEM) results revealed that the P/C-L films formed a compact microstructure with tight interlayer adhesion. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of intermolecular hydrogen bonds within the P/C-L films without the formation of new chemical bonds, and X-ray diffraction (XRD) indicates that the crystallinity of the P/C-L films was dominated by that of PVA. P/C-L films exhibited a dual-surface structure with a hydrophobic CS layer and a hydrophilic PVA layer, broadening their potential application range. The P/C-L films demonstrated superior water resistance and light transmittance to the P-C-L films. When the LAE content increased from 0% to 10%, the P/C-L films displayed a more stable range of variation concerning visible light transmittance, water contact angle (CS layers), and moisture absorption than that of the P-C-L films, with the corresponding changing values being 86.86% to 62.09%, 96.79°to 72.46°, and 8.35% to 19.78%, respectively. Regarding antibacterial properties, the P/C-L films exhibited significantly enhanced activity across all LAE concentrations. Notably, P/C-L films at 2% LAE already outperformed P-C-L films at 4% LAE. At an LAE content of 10%, the inhibition zone diameters of the P/C-L films against