A thermally stable/durable, water/oil repellent coating composed of polymethylsilsesquioxane (PMSQ) was successfully fabricated through a simple sol-gel reaction of methyltriethoxysilane.(1) SEM and AFM confirmed that the resulting coating was visibly transparent and smooth (Rrms < 0.3 nm). This PMSQ surface showed statically hydrophobic (?S= ca. 85�) and oleophilic (?S= ca. 35�) properties, but unusually, had excellent dynamic dewettability. Small volumes of probe liquids such as water and n-hexadecane can be easily set in motion to move across the surface when the substrate tilt angle is ~10� at room temperature. Thanks to a thermally stable Si-CH3 bond, this excellent water/oil repellency remained even after the thermal treatment up to 350�C for 24 h in air   , which exceeds decomposition temperature of conventional perfluorinated surfaces. Investigation of the repellent properties of PMSQ surfaces at high temperatures (~300�C) using thermally stable probe liquids, such as silicone oil and polyphenylether, revealed that static contact angles (CA's) exhibited a positive temperature coefficient, i.e a comparable increase in static CAs of these probe liquids at elevated temperatures. Based on this fundamental surface property, we have successfully manipulated probe liquids to migrate from higher temperature regions to lower regions through a thermally-induced gradient of surface tension   .

Thermally-responsive, durable, water/oil repellent coating using polymethylsilsesquioxane

247th National Meeting (2014)

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