Amphiphiles as hydrophobicity regulator: fine tuning the surface hydrophobicity of an electropolymerized film

Smart clean surfaces exhibiting reversible superhydrophilic to superhydrophobic transitions have been widely fabricated. A myriad of complex fabricating procedures have evolved over the years. Here, we demonstrate an apparently simple approach, wherein we utilized the attractive interaction between an unfabricated electropolymerized film and negative charge bearing amphiphilic molecules to precisely control the hydrophobicity of the surface of the film. We also demonstrate the use of different hydrophobic molecules to plug the voids created by the uneven distribution of the attached amphiphiles' long hydrocarbon tails on the film surface. Water drop contact angle revealed that by the used technique, surface hydrophobicity can be tuned to any desired value. Moreover, the film surface exhibited a high adhesive force toward the water droplets, thus preventing them from rolling or dropping down. In addition, the tuning process can be completely reversed and repeated by altering the applied potential. The interaction between the amphiphiles and the film surface was confirmed by ATR-IR. Scanning electron micrographs revealed that the film surface underwent no morphological modifications upon interaction with the amphiphiles.