Electrodeposited polymer films with both superhydrophobicity and superoleophilicityw Thierry Darmanin, Mael Nicolas* and Fre´de´ric Guittard Received 19th March 2008, Accepted 23rd April 2008 First published as an Advance Article on the web 3rd June 2008 DOI: 10.1039/b804617d Electrodeposited films of poly(ethylenedioxythiophene) (PEDOT) present a rough morphology and are wettable by water and oil. The covalent binding of low free energy fluorinated chains on the monomer before polymerization lowers the surface energy of the electroformed polymers sufficiently to give rise to superhydrophobic behaviour while conserving superoleophilicity. It holds the promise of an interesting candidate for the separation of water and oil. Introduction In the last decade, great interest in superhydrophobicity and superoleophobicity (contact angles with water and oil, respec- tively, greater than 1501), superhydrophilicity and superoleo- philicity (contact angles with water and oil, respectively, close to 01) of materials surfaces developed because of their great importance in daily life as well as in many industrial and biological applications. 1–8 This wetting behaviour strongly depends both on the chemical composition and on the micro- structure of the surface. 9 In contrast to the superhydrophobic and, to a less extent, superoleophobic surfaces which have attracted great interest and for which a lot of novel methods have been developed, there are only a few reports on both superhydrophobic and superoleophilic surfaces. 10 This lack of scientific papers concerning this type of surfaces is surprising when one considers that they can be used for the effective separation of oil and water for industrial applications as testified by the lot of patents registered these last years. 11 The best-known example of a natural surface with this dual property is the lotus leaf Nelumbo nucifera. 12,4b Superhydro- phobicity is attributable to a combination of surface composi- tion and multiple-scale roughness. On the other hand, a liquid with lower surface tension such as hexadecane spreads on the surface and leads to a contact angle of 01. Mimicking nature, Feng et al. 10a first report the fabrication of a superhydrophobic and superoleophilic film by using the block-like structure of a polytetrafluoroethylene film coated onto a stainless steel mesh via a spray-and-dry method. In the last two years, other materials with such a unique property have been developed, including porous polyurethane films combined with a polystyrene microsphere, 10b boehmite mem- branes obtained from anodic aluminium oxide films by a two- phased thermal approach, 10c structured copper mesh films fabricated by electrochemical deposition and followed by modification with long chain fatty acids, 10d and helical hybrid silica bundles synthesized by sol-gel polycondensation. 10e Typically, in the previous examples, a low surface energy material, intrinsically hydrophobic and oleophilic, is con- verted into superhydrophobic and superoleophilic by an ap- propriate surface design that increases roughness. The same result should be obtained by adequately lowering the surface energy of a rough hydrophilic and oleophilic material. Herein, following the later approach, we report the simple fabrication of superhydrophobic and superoleophilic polymer films obtained by electropolymerization of fluorinated ethyle- nedioxythiophene (EDOT) monomers on indium tin oxide (ITO) and gold (Au) conductive electrodes. These electrode- posited films exhibit both coarse-scale and fine-scale roughness and contain covalently attached low free energy substituent leading to this unique wetting property. They also demon- strate exceptional long-time stability without any loss of properties. Experimental Synthesis of the fluorinated monomers EDOT-RF n : 5 mmol of nonafluoroheptanoic acid, tridecafluorononanoic acid or hep- tadecafluoroundecanoic acid synthesized as previously de- scribed, 13 5 mmol of N,N 0 -dicyclohexylcarbodiimide (DCC) and 0.5 mmol of 4-dimethylaminopyridine (DMAP) were mixed under nitrogen with 25 mL of CH 2 Cl 2 in a 50 mL three-necked flask. The reaction mixture was stirred for 1 h at room temperature. Afterwards, 5 mmol of (2,3-dihydrothie- no[3,4-b][1,4]dioxin-2-yl)methanol 14 was added and stirring was continued overnight. After filtration and evaporation of the solvent, the crude product was purified by liquid chroma- tography (eluent: ether/cyclohexane 1 : 1). Preparation of the electrodeposited PEDOT and PEDOT- RF n films: electrochemical polymerization was performed at room temperature in a three-electrode cell in thoroughly dried acetonitrile containing 100 mmol L 1 of tetra-n-butylammo- nium hexafluorophosphate Bu 4 NPF 6 as the supporting elec- trolyte and 20 mmol L 1 of monomer. The film was potentiostatically electroformed with an anodic limit close to the irreversible oxidation peak potential of the monomer, e.g. 1.50–1.55 V/ECS, under the following conditions: working Institut de Chimie de Nice (ICN), FR 3037, Laboratoire de Chimie des Mate ´riaux Organiques et Me ´talliques (CMOM), EA 3155, Universite ´ de Nice-Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 2, France. E-mail: nicolasm@unice.fr; Fax: þ33 4 92 07 61 11; Tel: þ33 4 92 07 61 96 w Electronic supplementary information (ESI) available: SEM images of PEDOT-RF n . See DOI: 10.1039/b804617d 4322 | Phys. Chem. Chem. Phys., 2008, 10, 4322–4326 This journal is  c the Owner Societies 2008 PAPER www.rsc.org/pccp | Physical Chemistry Chemical Physics Published on 03 June 2008. Downloaded by University of Nice Sophia Antipolis on 22/06/2013 08:15:59. View Article Online / Journal Homepage / Table of Contents for this issue