Robustness tests on superoleophobic PEDOP films

Abstract

We report the synthesis and the characterization of superoleophobic electrodeposited polymer surfaces obtained from original fluorinated 3,4-ethylenedioxypyrrole (EDOP) derivatives. Semi-fluorinated chains of three different lengths (F-octyl, F-hexyl and F-butyl) were grafted to EDOP via a n-hexyl chain. The films elaborated by imposed potential are characterized by static and dynamic contact angle measurements (with water and hexadecane), robustness tests, scanning electron microscopy and optical profilometry. Robust superhydrophobic surfaces (contact angles of water greater than 140° after applying an external pressure) were produced from F-hexyl derivatives and robust superhydrophobic and superoleophobic surfaces (contact angles of hexadecane greater than 140° after applying an external pressure) were produced from F-octyl derivatives. These surfaces presented a peculiar double-scale surface structure (micro- and nanostructuration). Oil-repellent properties are highly depending on the deposition charge i.e. on polymer growth stage. The surface roughness parameters are given at various steps of the polymer growth and we thus identify microstructure profiles from which high oil-repellent properties are reached. The presence of oleophilic n-hexyl spacers has no prejudicial effect on superoleophobic properties obtained with F-octyl and F-hexyl chains but induces a decrease of oleophobicity with F-butyl chains because of the low interchain interactions of these short F-butyl chains.