Superhydrophobic conducting polymers with switchable water and oil repellency by voltage and ion exchange

Abstract

In 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⁻) especially modify the oil-repellency. Here, the highest oleophobic properties are obtained with the inorganic ions (ClO₄⁻ and BF₄⁻).