Micro-nano-engineered slippery liquid-infused porous surface coating with highly sustainable superhydrophobicity and omniphobicity

Abstract

Omniphobic coatings designed to repel liquid contamination off the surface can be used in various industries such as automotive, constructions, oil-water separation, anti-fouling marine devices, etc. Various methods have been investigated in the past decade to achieve omniphobicity in which majority of them have proven to be either complex, expensive, or impractical for large scale production. This study has employed a simple three-step, micro-nano-structuring fabrication technique to create physico-chemically and thermo-mechanically robust slippery liquid-infused porous surfaces (SLIPS). Polydimethylsiloxane (PDMS) was used as a base resin engineered with chemical bonding to ZnO micro particles and further physical trapping to hydrophobized TiO2 nano particles to create a hierarchy structure able to repel water and create omniphobicity. With very low contact angle hysteresis (CAH) of <1° and a low tilting angle of <5° for various liquid test subjects, the final coating displays excellent hydrophobicity and omniphobicity in spite of going through harsh mechanical tests such as the cross-hatch and scotch tape tests, pressure tests up to 100 N (500 kPa), thermal stability tests by exposure to low and high temperatures (−18 °C to 120 °C), and chemical pH tests from 1 to 13. We believe that the simple and low-cost micro-nano-engineering approach can be easily scaled up and is suitable for a variety of applications for self-cleaning and hydrophobic purposes.