A sustainable biomass adhesive based on the biomimetic "seaisland" structure, featuring boiling water resistance and antibacterial properties

Abstract

Chitosan (CS) based adhesive has shown promising potential as an environmentally friendly alternative to urea-formaldehyde adhesive due to its environmental and sustainable characteristics. However, practical application of chitosan-based adhesives has been limited by inadequate bonding strength and poor water resistance. To address these challenges, an innovative chitosan adhesive with containing varying quantities of rosin acid emulsion (RAE) featuring a unique "seaisland" structure was developed. Using response surface methodology, the formulation and hot-pressing parameters were optimized, yielding the optimal conditions of CS-5%RAE processed at 200 °C under 1 MPa for 10 min. The dry and wet shear strengths of CS-5%RAE adhesive were 1.48 and 1.05 MPa, respectively, which were higher by 32.14% and 208.82%, respectively, than that of the CS adhesive. The bonding mechanism between the CS-RAE adhesive and wood was examined using SEM coupled with EDS mapping to study interfacial morphology and elemental distribution before and after bonding. Furthermore, the CS-RAE adhesive exhibited exceptional antibacterial activity, with 99.99% inhibition rates against both S. aureus and E. coli. This study demonstrates a novel functionalization approach for developing high performance chitosan-based adhesives with dual functionality, offering new possibilities for sustainable wood composite manufacturing.