Novel and cutting-edge applications for a solvent-responsive superoleophobic–superhydrophilic surface: Water-infused omniphobic surface and separating organic liquid mixtures

Abstract

Superoleophobic–superhydrophilic surface has arousing massive research interests owing to its remarkable advantages in applications including liquid-liquid separation, anti-fogging and liquid transportation. But such superwetting surface has been considered counterintuitive since a given superoleophobic surface tends to repel water based on the classical surface free energy theory. Although significant progresses have been achieved for fabricating such superwetting surfaces, the existing attempts for searching the most cutting-edge and state-of-the-art functions are still extremely rare. In this work, we have successfully fabricated a stable superoleophobic–superhydrophilic surface by spraying an all-in-one suspension containing silica nanoparticles, aluminium phosphate, and Capstone FS-50 in ethanol-water cosolvent. The stable coating on various substrates displayed clever solvent-responsive behavior that highly polar liquid droplets can quickly wet surface while nonpolar liquid droplet can bead up, even after suffering from mechanical and chemical attacks. Thanks to the superhydrophilic porous surface hierarchy, a novel water-infused slippery surface can be achieved without using any costly low-surface energy lubricants. Based on the selective wettability caused by polarity interaction difference, the coated mesh can successfully achieve repeatable separation of immiscible polar liquid-nonpolar liquid mixtures in a high-efficiency mode, even for the liquid pair with a small surface energy difference of 3.1 mJ m−2.