Credit: © 2009 ACS

Antiwetting properties have attracted much research interest, and natural or biomimetic superhydrophobic surfaces are being investigated for various applications, such as self-cleaning or antisoiling materials. Natural materials that are oil-repellent (superoleophobic), however, are very rare and difficult to synthesize because oils have a very low surface tension, and therefore much more of a tendency to spread.

Electrochemical polymerization has previously been used to easily make superhydrophobic surfaces. Now, Thierry Darmanin and Frédéric Guittard at the University of Nice Sophia Antipolis in France have used it to prepare1 superoleophobic films in a one-pot reaction. Monomers containing an alkylenedioxy bridge and a highly fluorinated side chain were polymerized and deposited on gold plates. The wettability of the resulting films by water, diiodomethane and hexadecane was investigated.

Lengthening of the fluorinated side chain did not lead to significant variations, but drastic changes in the wettability characteristics of the surfaces were observed when the length of the alkylenedioxy bridge was modified. Monomers with a propylenedioxy spacer formed superhydrophobic, sticky surfaces. With an ethylenedioxy bridge instead, however, the films obtained were superoleophobic as well as superhydrophobic, and their affinity with water was so low that droplets could bounce on it.

This effect could be because of the nanoporosity of the ethylenedioxy-containing films, which decreases the droplet–surface interactions, and could lead to new dual water- and oil-repellent materials.