Sustainable cellulose nanofiber/hydrophobic silica nanoparticle coatings with robust hydrophobic and water-resistant properties for wood substrates

Hydrophobization of wood is pivotal for enhancing the utility of wood products. Traditional hydrophobic coatings, primarily petrochemical-based, are now being replaced by environmentally friendly silane-coupled inorganic nanoparticles. However, these alternatives face challenges like poor dispersion stability and weak wood surface adhesion. Our research introduces cellulose nanofibers (CNFs) into the condensation process of silica nanoparticles, creating a CNFs/silica nanoparticle composite. This composite exhibits remarkable dispersion stability and adjustable viscosity, leading to an improved hydrophobic silica/CNFs coating. Its versatility allows for various application methods, including spray, dip, and brush coating. Remarkably, the composite maintains a water contact angle of about 151°, demonstrating excellent water repellency, even with hydrophilic CNFs. The CNFs also enhance the interaction with wood surfaces, boosting the durability of the coating. This innovative approach not only improves storage stability and workability but also ensures uniform hydrophobicity and durable coating formation. Our findings suggest that CNFs derived from lignocellulosic biomass could ultimately be incorporated into environmentally friendly wood coating materials, significantly improving the shortcomings of conventional hydrophobic coatings while reducing dependence on petroleum-based products.