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Prof. Bob Cohen and post-doc Anish Tuteja present design rules for oil-repellant materials.

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Droplets of water (colored blue), methanol (colored green) and octane (colored red) on a lotus leaf surface covered with electrospun fibers of PMMA + 44 wt% fluorodecyl POSS. This image demonstrates the ‘omniphobicity’ (i.e. ability to repel any and all types of liquids) of our electrospun surfaces. The reflective surface visible underneath both the liquid droplets is a signature of trapped air or the formation of a liquid-solid-air ‘composite’ interface. The liquid droplets shown in the image are between 2 – 3 mm in diameter. Image courtesy of Anish Tuteja / Wonjae Choi.


 
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Droplets of three different liquids – water (dyed blue), oil (hexadecane, dyed red) and alcohol (1-butanol, dyed yellow) on a dip-coated duck feather. The dip-coating process enables us to provide a conformal coating of extremely low surface energy fluoroPOSS molecules on the surface of a duck feather. The synergistic effects of the duck feather’s re-entrant surface texture and the low surface energy of fluoroPOSS molecules allow the feather to easily repel various kinds of liquids (with a wide range of interfacial tensions) from its surface. We term such a surface “omniphobic”. The reflective surface visible underneath all the liquid droplets is a signature of trapped air or the formation of a liquid-solid-air ‘composite’ interface. All droplets shown in the image are between 2 – 3 mm in diameter. Image courtesy of Anish Tuteja / Wonjae Choi.


   
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Droplets of water (dyed blue) and oil (hexadecane, dyed red) on a model dip-coated surface possessing re-entrant texture. The dip-coating process enables us to provide a conformal coating of extremely low surface energy fluoroPOSS molecules on the solid substrate. The synergistic effects of the re-entrant surface texture and the low surface energy of the fluoroPOSS molecules allow the dip-coated surface to easily repel various kinds of liquids from its surface. We term such a surface “omniphobic”. The reflective surface visible underneath both the liquid droplets is a signature of trapped air or the formation of a liquid-solid-air ‘composite’ interface. The droplets shown in the image are ≈ 3 mm in diameter. Image courtesy of Anish Tuteja / Wonjae Choi.