Laccase-Catalyzed Polymerization Drying Of Chinese Lacquer Sap With Tio2 Nanoparticles

Nano-TiO2/lacquer hybrid coatings are prepared by the blend of nano-TiO2 and lacquer sap. Nano-TiO2 particles are involved in the laccase-catalyzed polymerization process of urushiol, which improves the properties of lacquer film. With increasing nano-TiO2 from 0 to 5 wt %, the drying time of lacquer film to reach hardened dryness decreases from >12 h to 8 h 30 min under 30 degrees C and 80% relative humidity. Gel permeation chromatography analysis shows that the addition of nano-TiO2 accelerates the polymerization of urushiol. It is also related to the formation of TiOC bonds due to the reaction between nano-TiO2 and the radicals produced by laccase-catalyzed oxidation. The pencil hardness, flexibility, and adhesion of hybrid lacquer film can be improved and reach 4H, 1 mm, and grade 2, respectively. Its inhibition rate against Escherichia coli and Staphylococcus aureus increases from 22.6% and -21.4% to 49.2% and 67.8%, respectively. Furthermore, nano-TiO2 hybrid lacquer films also possess higher thermo-stability than the raw lacquer film. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45865.