Tough, antibacterial fish scale gelatin/chitosan film with excellent water vapor and UV-blocking performance comprising liquefied chitin and silica sol

Developing biodegradable, and non-toxic materials to replace petrochemical polymers is important. Herein, the waste fish scale-derived gelatin was chosen to prepare an environmental-friendly film. While the natural product of fish scale gelatin (FSG) films has the weakness of low humidity stability, poor antibacterial activity, poor mechanical strength, and weak UV absorption. Hence, a novel multifunctional and mechanically robust FSG-based composite is proposed using chitosan (CTS) as the crosslinking matrix, liquefied chitin product (LCP), and silica sol as the functional fillers. The thermal decomposition kinetics and pyrolysis analysis show that the functional filling components were compatible with the FSG/CTS-based macromolecule matrix. The incorporation of LCP significantly improved the film's flexibility, antibacterial capacity, and UV absorption. The addition of the silica sol also increased the mechanical strength and water tolerance with decreased water vapor permeability (WVP). The increasing apparent activation energy (Ea) along with pyrolysis reactions could correlate well with the composite film's progressive crosslinks. This study demonstrated a renewable FSG/CTS/LCP/Si composite film with a much-improved property that could have potential applications in film-based packaging.