Smooth and transparent hydrophilic surfaces showing good water sliding properties

A. Hozumi, S. Nakamura, C. Urata, R.J. Archers
National Institute of Advanced Industrial Science and Technology,
Japan

Keywords: hydrophilic surfaces, sol-gel, hybrid films, dynamic wettability

Summary:

The development of novel liquid-repellent surfaces inspired by examples from nature, including the lotus leaf, the water striders’ leg, the pitcher plant, etc., have attracted much attention across many scientific disciplines with interest ranging from fundamental research to practical applications. Such functional surfaces have been commonly prepared by combining textured surfaces with perfluorinated compounds such as perfluoroalkylsilanes or perfluorinated fluids. In this talk, we simply questioned: “Are micro/nanostructures, perfluorinated compounds, or extremely large contact angles (CAs) truly necessary to achieve excellent liquid sliding properties”? We introduce our approaches to achieving surfaces which show excellent dynamic dewetting properties against water, without relying on both complicated surface roughening techniques, or expensive and environmental damaging perfluorinated compounds. Our surfaces are very smooth and show unusual dynamic dewettability, that is, “statically hydrophilic but dynamically hydrophobic” properties on which water droplets can move smoothly without pinning at low substrate tilt angles despite their fairly small static CAs.