UV resistant wood coating based on zinc oxide and cerium oxide dispersed linseed oil nano-emulsion

Natural wood is susceptible to weathering deteriorations and hence needs application of coating to increase its service life during exterior use. Due to the environmental issues associated with synthetic wood coatings, the current focus is on development of environmentally safer options for wood protection. In this paper, we propose an UV resistant and environment friendly wood coating based on zinc oxide (ZnO) and cerium oxide (CeO2) nanoparticles embedded linseed oil nanoemulsion. Preparation of nanoparticle dispersed linseed oil nanoemulsion with tween 80 as a surfactant was carried out using homogenization and ultrasonication techniques. Nanoemulsions were characterized on the basis of particle size and polydispersity index measured using dynamic light scattering technique. Morphology of nanoemulsions was examined using optical and scanning electron microscopy. Storage stability of nano emulsion was evaluated by measuring effective particle size and zeta potential over a period 14 days. Pinus radiata wood specimens were coated with ZnO and CeO2 nanoparticles (concentration 0.5-2.0% w/v) dispersed linseed oil-water nanoemulsions and UV stability of coated wood was accessed in an accelerated weathering tester by evaluating color changes on wood surfaces using CIE color parameters. Fourier transform infrared spectroscopy was used to elucidate the chemical changes on the irradiated surfaces. The results (color changes and chemical degradation) indicate significant improvement in UV shielding of wood surfaces coated with oil nanoemulsion with nano particle dispersion.