Highly Efficient UV Protection of the Biomaterial Wood by A Transparent TiO₂/Ce Xerogel

Abstract

Titanium dioxide is widely used in sunscreens because of its strong ultraviolet (UV) light absorbing capabilities and its resistance to discoloration under UV exposure. However, when deposited as a thin film, the high refractive index of titanium dioxide typically results in whiteness and opacity, which limits the use of titanium dioxide for material surfaces, for which long-term natural appearance is of high relevance. Since the whitish appearance is due to the strong light scattering and reflection on the interface of oxide particles and air, one can increase the transparency of TiO coatings by forming a continuous TiO layer. The purpose of the present article is 2-fold. First, we show that, in the presence of cerium ammonium nitrate, titanium dioxide can be turned from a white powder into a TiO/Ce xerogel via a facile bottom-up fabrication process. Second, we demonstrate that the transparent TiO/Ce xerogel can diminish surface deterioration induced by UV light and preserve the natural appearance of the highly abundant biomaterial wood. Furthermore, EPR spectroscopy revealed that the TiO/Ce xerogel coating suppresses free radical generation on wood surfaces upon UV irradiation. Our research expands the applicability of the protective effect of titanium dioxide to coatings for natural engineering materials, which will become increasingly important in future bioeconomies.

Surface hardness and flammability of Na2SiO3and nano-TiO2reinforced wood composites

“…17 Further, transparent TiO 2 /Ce xerogel coatings deposited on spruce (Picea abies) wood were shown to be an effective UV absorber and might act as protective system against photo-initiated degradation. 18 It is well known that of the main constituents of the wood, i.e. cellulose (40 to 50% of the wood composition), hemicelluloses (25 to 30%) and lignin (15 to 30%), lignin absorbs most strongly in the UV/visible region of the solar radiation.…”

Optically Transparent Wood: Recent Progress, Opportunities, and Challenges

“…The main modification strategies include modification of the cell wall, cell wall/lumen interface modification, and lumen filling ( Figure a) . Modification can be performed by chemical reactions of small molecules, physical adsorption, physical filling of monomer liquids, thermal treatment, or complex combinations. Successful wood modification examples include preparation of magnetic wood, fire retardant wood, conductive wood, and stimuli‐responsive wood .…”

Novel Attribute of Organic–Inorganic Hybrid Coatings for Protection and Preservation of Materials (Stone and Wood) Belonging to Cultural Heritage

“…Despite the fact that the loss of mechanical properties of weathered wood is limited to the upper cell rows and therefore negligible for construction purposes, the optical appearance is strongly altered [89]. The polymer lignin undergo bond cleavage and hydrogen abstraction, resulting in the formation of radicals or peroxides easily decomposed to produce chromophoric groups (such as carbonyl and carboxyl groups), and directly responsible for the wood yellowing/darkening [90].…”