Quick Chemical Trick Makes Surfaces Slick

A quick dip in a special silane solution followed by a few moments of drying is all it takes to give a surface an omniphobic coating that repels both water and organic liquids. Such superslippery coatings could find use on windshields and airplane wings (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201509385). Previous examples of omniphobic surfaces have relied on either constructed nanoscale features or a thin layer of liquid to make other liquids slide off. But under enough pressure liquids can penetrate a nanostructured surface so that they’re no longer repelled, and in the case of surfaces that have a liquid layer, the liquid can be depleted. Liming Wang and Thomas J. McCarthy of the University of Massachusetts, Amherst, have come up with a different approach: They covalently attach a layer of liquid onto a substrate. When other liquids such as water and toluene encounter the surface, they slide right off. Making the omniphobic coating is easy and fast, McCarthy tells C&EN. One simply dips the substrate into an isopropanol solution of dimethyldimethoxysilane and sulfuric acid. After a few minutes of drying, the coating is ready to repel liquids.