Nanoparticle-based impregnation coatings for wood: improving hydrophobicity, mechanical properties, and blue stain fungi resistance through structure–property relationship

Abstract

Wood is an organic material that is highly susceptible to moisture, which compromises its performance, accelerates decay, and promotes mould growth, thereby reducing its service life. This study presents a comparative assessment of cost-effective solutions for enhancing the hydrophobicity, mechanical properties, and blue-stain resistance of wood surfaces by evaluating the effects of silicon dioxide (SiO2), zinc oxide (ZnO), and titanium dioxide (TiO2) particle coatings on Scots pine wood. Low-concentration particles were applied via an impregnation coating method, resulting in the formation of a nanocomposite between the wood and the particles. The coated and uncoated samples were then exposed to blue-stain fungi. To further analyse the effects, the exposed samples were characterised using scanning electron microscopy (SEM) to analyse particle morphology and observe fungal colonisation, and energy-dispersive X-ray spectroscopy (EDS) to determine elemental distribution. Fourier-transform infrared spectroscopy (FTIR) was used to confirm interactions between the nanoparticles and wood components. Mechanical and physical tests were conducted to evaluate the durability and resistance of the coated wood against blue-stain fungi. The results showed a significant improvement in surface hydrophobicity following coating application, which remained stable even after exposure to fungi. Moreover, distinct differences in fungal resistance were observed among the nanoparticle types, with ZnO showing the highest effectiveness. A new approach was also introduced to assess the mechanical performance of the coatings. This study offers insight into nanoparticle coatings as a sustainable strategy for enhancing wood surfaces in construction and outdoor furniture applications.