A facile single-step strategy for sustainable, antibacterial, high-barrier PVA coated paper: Using anhydride as solvent and crosslinker dual-functional agents

The excessive use of non-biodegradable plastic food packaging has led to severe environmental pollution, highlighting the urgent need for eco-friendly materials that are biodegradable, environmentally sustainable, and effective in food preservation. This work discusses the feasibility of preparing multifunctional paper packaging materials coated by poly(vinyl alcohol) (PVA) and natural thymol (THY), a poor water solubility naturally derived phenolic compound with antimicrobial activity. An emulsion was prepared using octenyl succinic anhydride (OSA) as the solvent for THY, xanthan gum as the emulsifier, and this emulsion was applied as a functional additive into PVA coating. OSA also served as a crosslinking agent for PVA, enhancing the coating density and improving the barrier properties of the coated paper. The results demonstrated that OSA did not reduce the antibacterial efficacy of THY, confirming the compatibility between OSA and THY. When the emulsion concentration was 3.0%, the water vapor permeability of the coated paper decreased from 4.75 × 10⁻¹ ³ to 3.02 × 10⁻¹ ³ kg·m/(m²·s·Pa) compared with PVA coated paper, and its oil resistance Kit rating reached 12. The THY/OSA/PVA coated paper extended the shelf life of strawberries to 8 days without visible spoilage. This work provides a promising strategy for the fabrication of multifunctional packaging material, offering a convenient method to integrate water insoluble solid functional components into bio-based degradable materials without traditional organic solvents. It advances the technology of environmentally friendly food packaging, provides insights for the development of active packaging and biodegradable materials, and lays a foundation for the future optimization and industrialization of such materials.