Atmospheric rf plasma deposition of superhydrophobic coatings using tetramethylsilane precursor

Non-fluorine-based organic-inorganic-hybrid coatings exhibiting superhydrophobic properties were prepared using a single-step process of atmospheric rf glow discharge plasma deposition with a tetramethylsilane (TMS) precursor. The plasma was generated with He in air and the TMS precursor concentration was 0.01-0.04 vol.% of the He carrier gas. The dissociation of TMS in the atmospheric plasma accompanied the formation of particulates through gas-phase condensation reactions, which lead to organic-inorganic-hybrid coatings with a root-mean-squared roughness in the ~ 30-80 nm range and a water contact angle of ~ 150°-165° on a variety of substrates including flat wafers, papers, and cotton fabric without any sample pre-treatments. Due to the excitation and dissociation of ambient molecules (oxygen, nitrogen, and water) in the atmospheric plasma, the produced coatings contained oxygen and nitrogen, in addition to silicon and hydrocarbon groups. The oxygen species in the film appears to be a part of Si-O-Si networks similar to silicone compounds. The films produced with TMS exhibited an improved environmental durability compared to purely hydrocarbon-based films deposited with the same atmospheric plasma process.