Directional growth of nanotubes on micelles by soft-template electropolymerization with varying hydrophobicity and strong water adhesion

Abstract

Inspired by the strong water adhesion found in gecko feet and rose petals, surfaces with nanotubes are prepared by soft-template electropolymerization. A solvent with low water-solubility (dichloromethane) is used with water to form a micellar solution stabilized by a surfactant. Fully-conjugated monomers are prepared by grafting thiophene and carbazole-based molecules onto naphthalene to favor deposition as opposed to polymerization as confirmed here by electrochemical characterization. The water content plays a fundamental role in the formation of nanotubes. The monomer has a huge influence on the surface structures even if just the position of the substituent changes (ortho, meta, or para). Extremely long nanotubes are obtained with carbazole in the meta-position, indicating the deposition is highly favored in one direction. Surfaces with both nanotubes and nanoparticles display the highest hydrophobicity, combined with strong water adhesion. Such surfaces could be used in the future for instance in water-harvesting systems, sensing platforms, and opto-electronic devices.