Mechanically durable, superomniphobic coatings prepared by layer-by-layer technique for self-cleaning and anti-smudge

Superomniphobic surfaces are of interest for anti-fouling, self-cleaning, anti-smudge and low-drag applications. Many bioinspired surfaces developed previously are of limited use due to a lack of mechanical durability. From a previously developed technique, an adapted layer-by-layer approach involving charged species with electrostatic interactions between layers is combined with an uncharged fluorosilane layer to result in a durable, superomniphobic coating. This technique can provide the flexibility needed to improve adhesion to the substrate with the addition of a low surface tension coating at the air interface. In this work, polyelectrolyte binder, SiO2 nanoparticles, and fluorosilane layers are deposited, providing the combination of surface roughness and low surface tension to result in a superomniphobic coating with droplets of liquids with surface tensions from 72 to 21 mN m−1 displaying contact angles exceeding 155° with low tilt angles. The durability of these coatings was examined through the use of micro- and macrowear experiments. These coatings currently display levels of transparency acceptable for automotive applications. Fabrication via this novel combination of techniques results in durable, superomniphobic coatings displaying improved performance compared to existing work where either the durability or the repellency is compromised.

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