UV-resistant and transparent hydrophobic surfaces by a facile dip-coating method

Hydrophobic surfaces were prepared with different chemistries by dip-coating. They showed excellent resistance to UV radiation after long-term exposure.

Water drops on a transparent surface.
Hydrophobic surfaces with high optical transparency are of great importance. Image source: Pexels / Pixabay (symbol image). -

Hydrophobic surfaces with good resistance to UV radiation and high optical transparency are of great importance for various technological applications. In a recent work, scientists report a simple one-step approach to prepare such surfaces by the deposition of two different kinds of silanes, trimethylchlorosilane (TMCS), and perfluorooctyltrichlorosilane (PFOTCS).

The surface coatings were obtained by dipping clean glass slides into the silane solutions of similar concentrations ( 0.1 M). To obtain the surface with the best hydrophobic character, the immersion time of the substrate in both silanes was varied. Contact angle measurements with a goniometer showed the average static water angle values to be 110° and 120° for the TMCS- and PFOTCS-coated surfaces respectively.

Light transmissivity similar to virgin glass

The resulting surfaces were optically transparent having a visible light transmissivity similar to virgin glass. Atomic force microscopy (AFM) measurements showed both surfaces to be smooth with average roughness values ≤ 10 nm. X-ray photoelectron spectroscopy of the PFOTS modified surfaces confirmed fluorine enrichment at the top of the surface.

Self-cleaning tests performed with dust particles showed the TMCS-coated surface to possess good cleaning characteristics. The synthesized surfaces retained their hydrophobic character after prolonged exposure ( 24 h) to concentrated UV light. The proposed preparation method is quite simple and can be applied to large-area substrates.

The study has been published in Progress in Organic Coatings, Volume 136.

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