Fabrication of water-resistant and flame-retardant polysaccharide-based adhesive films via metal-phenolic network impregnation assembly

In wood industry applications, conventional polysaccharide-based adhesives often suffer from problems, mainly high viscosity and low solid content. This study proposes a preparation method for a polysaccharide-based biomass resin film that combines excellent bonding performance with flame-retardant properties. To begin with, a precursor film composed of sodium carboxymethyl cellulose and hyperbranched polyamide was prepared via a simple solution casting method. Then, this precursor was immersed in an aqueous mixture solution of tannic acid and ferric chloride to successfully construct the hybrid bio-based resin film. The film structure is supported by electrostatic interactions and further reinforced by a metal-phenolic network, resulting in good water stability and flexibility. After rapid water activation (approximately 1 min), the CMC-HBPA-TA@Fe 3 + film exhibited outstanding bonding performance on poplar and eucalyptus wood veneer, with wet-state bonding strengths reaching 2.25 MPa and 2.13 MPa, respectively. These values far exceed the 0.70 MPa requirement specified in the GB/T 9846–2015 standard, more than doubling the standard requirement. Furthermore, plywood bonded and hot-pressed with this film demonstrated self-extinguishing properties on the surface. This study provides innovative insights and application pathways to solve the problem about development of energy-efficient bio-based resin films. Schematic of a polysaccharide-based bio-resin film fabrication method combining strong adhesion and flame retardancy. • A simplified preparation strategy for polysaccharide-based resin films. • Water activation enables rapid and robust bonding of the bio-based adhesive film. • The hot-pressing formed dual-crosslinked network enhances water resistance. • A metal-phenolic network imparts excellent flame retardancy.