Eco-friendly fabrication of durable superhydrophobic coatings on wood using modified ZnO–TiO ₂ nanocomposite and bio-based components

Wood exposed to outdoor environments undergoes rapid degradation due to UV radiation, moisture, and microbial activity, resulting in surface discoloration and reduced durability. Traditional protection methods often fail to ensure long-term photostability and sustainability. This study develops bio-based superhydrophobic coatings for spruce wood using a hybrid formulation containing epoxy resin, hardener, beeswax, linseed oil, and ZnO–TiO2 nanoparticles either unmodified or modified with fatty acids. An experimental design approach was applied to optimize the coating composition and evaluate UV-shielding efficiency. The optimized coatings achieved water contact angles above 150° and provided strong UV shielding (>90%), effectively limiting photodegradation. Additionally, the hybrid nanoparticle system exhibited excellent antimicrobial activity, achieving over 95% inhibition of microbial growth compared to uncoated spruce. These results demonstrate that this eco-friendly formulation significantly improves the UV resistance, water repellency, and antimicrobial performance of wood for long-term protection.