Deposition of Coated Titanium Dioxide Nanoparticles with Controllable Wetting Properties

Liquid Flame Spray (LFS) method can be used in synthesis and deposition of nanoparticles. The deposited nanoparticle coating forms a functional surface on top of the substrate. We have previously demonstrated that the coating can be applied on paperboard in a roll-to-roll process in a pilot scale with the substrate speed up to 150 m/min [1]. Titanium dioxide nanoparticles are hydrophilic by nature but with a careful selection of the coating parameters the substrate, especially paper board, can participate in the process. Even without affecting the visual or mechanical properties of the substrate some combustion fumes might be released from the substrate. The combustion fumes condense on top of the LFS deposited titania nanoparticles forming a coating on top of the particles [2]. The coating layer is only a few nanometres thick and thus transparent. The photoactive properties of titanium dioxide are preserved as the coating on top is transparent and therefore UV-light can be used in switching the wetting properties of the surface from superhydrophobic to superhydrophilic [3].

[1]   Mäkelä, J.M., Aromaa, M., Teisala, H., Tuominen,  M.,  Stepien, M.,  Saarinen,  J.J.,  Toivakka  M. and  Kuusipalo, J., Nanoparticle deposition from liquid flame spray onto moving roll-to-roll paperboard material, Aerosol  Science  and  Technology,  45, 827-837, 2011.

[2]   Aromaa, M., Arffman, A., Suhonen, H., Haapanen, J., Keskinen, J., Honkanen, M., Nikkanen, J.-P., Levänen, E., Messing, M.E., Deppert, K., Teisala, H., Tuominen, M., Kuusipalo, J., Stepien, M., Saarinen, J.J., Toivakka, M. and Mäkelä, J.M., Atmospheric Synthesis of Superhydrophobic TiO₂ Nanoparticle Deposits in a Single Step using Liquid Flame Spray, Journal of Aerosol Science, 17 pages, accepted 2012.

[3]   Stepien, M., Saarinen, J.J., Teisala, H., Tuominen, M., Aromaa, M., Kuusipalo, J., Mäkelä, J.M. and Toivakka, M., Surface chemical analysis of photocatalytic wettability conversion of TiO₂ nanoparticle coating, Surface Coatings Technology, 17 pages, submitted 2011.