Bioinspired surfaces with strong water adhesion by electropolymerization of thieno[3,4-b]thiophene with mixed hydrocarbon/short fluorocarbon chains

Abstract

Here, in the aim to replace long perfluorinated chains (C8F17) in polymer we use both a short C4F9 perfluorinated chain and a hydrocarbon chain a various length (from C2 to C12). These chains are grafted to thieno[3,4-b]thiophene monomers to perform electrodeposited conducting polymer films with high hydrophobic properties. Two solvents are used: dichloromethane (CH2Cl2) and dichloromethane saturated with water (CH2Cl2 + H2O) in order to release also in-situ O2 and/ or H2 gas bubbles. In CH2Cl2, spherical particles covering the surface are observed with short alkyl chains and large wrinkles with long alkyl chains. The highest hydrophobicity θw = 139.3° are obtained with Thieno-F4-C6 after 5 deposition scans, which presents also strong water adhesion. In CH2Cl2 + H2O, the surfaces are smoother and traces of very large bubbles are present but only with short alkyl chains. However, the polymer growth is inhomogeneous because the substituents are too flexible to stabilize the released gas bubbles. The preliminary results are encouraging and more rigid substituents or spacers could be envisaged in the future to induce homogenous porous structures.