Surface Modification of Fluorine‐Free Superhydrophobic Materials with (Ultra‐)Thin TiO ₂ Layers

Fluorine‐free superhydrophobic (SH) thin films, prepared by aerosol‐assisted chemical vapor deposition (AACVD) are surface‐modified with titanium dioxide (TiO 2 ) deposited via atomic layer deposition (ALD). This modification results in significant changes to wettability, with a water contact angle reduction of ≈60° for a TiO 2 layer just 4 nm thick. The fluorine‐free SH films are deposited from a mixture of two fatty acids (stearic acid and palmitic acid), polydimethylsiloxane, and SiO 2 nanoparticles. 100–1000 precursor cycles are deposited via ALD using tetrakis(dimethylamido)titanium(IV)/ozone onto the fluorine‐free SH films providing a TiO 2 film thickness of 4–100 nm. Tape peel testing confirms strong adhesion between the SH undercoat and TiO 2 thin film. The dual‐layered films SH/TiO 2 /xC (where xC is indicative of the number of ALD cycles), deposited with the thinnest TiO 2 films (<12 nm), demonstrate maintained hydrophobicity, despite the equivalent TiO 2 layers (without the SH underlayer), deposited on fluorine‐doped tin oxide glass substrates, exhibiting hydrophilicity.