In this work, we report the possibility to selectively switch by voltage and anion exchange the water-repellent properties, in comparison with the oil-repellent properties, of copolymers containing both fluorinated chain (EDOT-F8) and pyridinium (EDOT-Py(+)) moieties. Here, the fluorinated chains are necessary to reach superhydrophobic properties while the pyridinium moieties allow the switching in the wettability by counterion exchange. Because, conducting polymers can exist in their oxidized and reduced state, here, we report also the switching of their wettability by voltage. The best properties (superhydrophobic properties with low hysteresis and sliding and good oleophobic properties) are obtained for a % of EDOT-Py(+) of 25 %. Surprisingly, by reducing the polymer by changing the voltage, a selective decrease in the contact angle of water is observed, whereas that of oils (diiodomethane and hexadecane) remain unchanged, making it possible to have higher contact angles with diiodomethane than with water. Here, the switching in the wettability is due to the change of the water droplet from the Cassie-Baxter state to the Wenzel state by changing the voltage. Because of the presence of highly polar pyridinium groups and their perchlorate counterions, the wettability of oil droplets (diiodomethane and hexadecane) is not significantly affected. This effect is confirmed by changing the counterions with highly hydrophobic ones (C8F17SO3(-), Tf2N(-), or BF4(-)). Such materials are excellent candidates for oil/water separation membranes.

International audienceIn order to elaborate superhydrophobic polymers with switchable water and oil-repellency, copolymers are prepared by electrodeposition. A fluorinated monomer (EDOT-F8) is used to reach superhydrophobic properties and a monomer containing an ammonium function (EDOT-N+) to induce changes in the surface wettability by ion exchange. We also study the change in the surface wettability by dedoping at a different voltage. Surprisingly, an increase in the water and oil repellency was observed by introduction of hydrophilic monomers (EDOT-N+), which is due to a modification in the surface morphology and more precisely to the presence of small spherical particles containing thin fibrils on their surface (multi-scale roughness). The dedoping and the ion exchange (ClO4- by BF4-, Tf2N- or C8F17SO3-) modify especially the oil-repellency. Here, the highest oleophobic properties are obtained with the inorganic ions (ClO4- and BF4-)

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Here, we report for the first time the use of a boronic ester as an efficient tool for reversible surface post-functionalization. The boronic ester bond allows surfaces to be reversibly switched from hydrophilic to hydrophobic. Based on the well-known boronic acid/glycol affinity, this strategy offers the opportunity to play with surface hydrophobic properties by adding various boronic acids onto substrates bearing glycol groups. The post-functionalization can then be reversed to regenerate the starting glycol surface. This pathway allows for the preparation of various switchable surfaces for a large range of applications in biosensors, liquid transportation, and separation membranes.