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January 19, 2017

Self-healing, super-slippery coating

Two steel balls sit in a pool of octane, a component of petroleum, that has been dyed yellow. Though the ball on the left has picked up streaks of the oily liquid, the ball on the right has repelled it due to a self-healing, super-slippery coating called X-SLIPS (slippery liquid-infused porous surfaces).

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Researchers at Pennsylvania State University developed the coating, which repels both water and oil, based on the slippery interior of the Nepenthes pitcher plant and the wax layer on the plant's leaves.

To make the coating, the researchers applied a 2.5-µm-thick layer of fluorinated silane to the sanded surface of a steel ball. A spritz of DuPont’s Krytox lubricant, a perfluorinated oil similar to Teflon, adheres tightly to the silane to create a surface that repells water and oil. After damaging the coating with blasts of oxygen plasma, or abusing it with 40-grit sandpaper, the researchers could restore the coating by simply heating it, causing the remaining silane to redistribute across the surface and re-adhere. Potential uses for the coating include on ship surfaces or in condiment packaging.

The research was supported by a National Science Foundation Faculty Early Career Development (CAREER) award (grant CMMI 13-51462). (Date image taken: 2014; date originally posted to NSF Multimedia Gallery: Dec. 16, 2016)

Credit: Jing Wang and Tak-Sing Wong, The Pennsylvania State University

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