Photocatalytic Silica–Resin Coating for Environmental Protection of Paper as a Plastic Substitute

Researchers from the Institute for Solid State Physics at the University of Tokyo, have developed a new formulation, Choetsu, a low-cost biodegradable coating that adds waterproofing and strength to simple paper. Choetsu is a combination of materials which, when applied to paper, spontaneously generates a strong and waterproof film when it makes contact with moisture in the air. The coating consists of safe and low-cost chemicals, mostly methyltrimethoxysilane, some isopropyl alcohol, and a small amount of tetraisopropyl titanate. Paper structures, for example food containers, are sprayed with or dipped into this liquid mixture and are dried at room temperature. Once dry, a thin layer of silica containing methyl, forms on the cellulose making up the paper and creates a layer of titanium dioxide nanoparticles, providing the strong and waterproof properties. Additionally, the porous silica–resin film has a high adsorptive capacity, efficiently capturing organic pollutants until they decompose via photocatalytic reactions. The coated paper can be used in place of the majority of plastics and degrades in an environmentally benign manner after disposal. 

Photo Yoko Iwamiya, Daisuke Nishio-Hamane, Kazuhiro Akutsu-Suyama, Hiroshi Arima-Osonoi, Mitsuhiro Shibayama, and Zenji Hiroi. “Photocatalytic Silica-Resin Coating for Environmental Protection of Paper as a Plastic Substitute”. Industrial & Engineering Chemistry Research; 2022



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