Fabrication of eco-friendly transparent wood for UV-shielding functionality

Recently, transparent wood (TW) has been considered for many applications, such as windows, energy storage, and electronic devices. This study presents the fabrication of eco-friendly TW using waste lignin as a resource to enhance the TW's performance by providing UV-shielding functionality. Three different pretreatment methods were explored for TW fabrication, including solar-assisted bleaching, steam bleaching, and NaOH delignification. The average size of the lignin nanoparticles (LNs) characterized using a scanning electron microscope and nanoparticle analyzer and was found to be around 100 nm. The LNs had zeta potentials of - 44.2 mV to - 34.9 mV for the first and sixth months, respectively. The transmittance of TW ranged from 20% to 80%, depending on the pretreatment and additional LNs content. By incorporating just 1% of LN, the TW composites were found to effectively block all UV-C, UV-B, and UV-A radiation while maintaining adequate visible light transmittance. The thermal stability, crystallinity index, and mechanical properties of wood and TW were investigated and compared. The NaOH delignification TW (Na-TW) has shown the highest transmittance, tensile strength, UVshielding functionality, and comparable thermal stability with solar transparent wood (SL-TW) and steam transparent wood (ST-TW) methods. These findings indicate that TW LNs nanocomposite is a promising candidate for UV-shielding window applications.