Dynamic Wetting Properties of Mesh Substrates with Tunable Water Adhesion.

In nature, wetting phenomena are present nearly everywhere and are a source of inspiration for liquid transportation. A good understanding of the underlying dynamic phenomena that governs wettability is therefore extremely important for researchers involved in bio-inspired surfaces. Herein, we study the adhesive behavior with water of mesh substrates modified with structured copolymers in order to tune the surfaces from parahydrophobic states (high water adhesion) to superhydrophobic states (low water adhesion). Using the ejection test method (ETM), a new technique that consists of the ejection of water droplets deposited onto a substrate with the aid of a catapult system, we experimentally demonstrate that the elasticity of the mesh substrate can be exploited for efficient vertical actuation of droplets.

A soft template approach to various porous nanostructures from conjugated carbazole-based monomers.

HYPOTHESIS: Controlling the size and the shape of nanostructures on surfaces is fundamental for various applications while the formation of porous structures such as nanotubes is particularly difficult. The templateless electropolymerization is a choice process that not only forms nanostructured surfaces, but also can tune their morphologies using different monomers. EXPERIMENTS: In this work, we used this soft-template and surfactant free electropolymerization in organic solvent to deposit for the first time carbazole-based monomers. Five different conjugated carbazole-based monomers are tested here. FINDINGS: We show that the shape of surfaces nanostructures is highly dependent on the amount of water present in the organic solvent and on the molecular structure of the carbazole monomers. Different morphologies are obtained from fibers to vertically aligned nanotubes and even porous membranes, depending on the monomer and on the electropolymerization method. The nanostructured surfaces reach superhydrophobic properties and their dynamical non-wetting behavior varies with the monomer and the electrochemical parameters.

Micellar formation by soft template electropolymerization in organic solvents.

HYPOTHESIS: The formation of porous nanostructures on surfaces and the control of their size and shape is fundamental for various applications. The creation of nanotubes is particularly difficult to implement without the aid of hard and rigid templates. Recently, methods that form nanotubular structures in a straightforward manner and without direct templating, e.g. soft templating, have been highly sought after. Here we propose the use of "soft templating" via self-assembly of conducting monomers during electropolymerization in organic solvents as a mean to form porous, nanotubular features. EXPERIMENTS: Naphtho[2,3-b]thieno[3,4-e][1,4]dioxine (NaphDOT) is employed as monomer for electropolymerizations conducted in dichloromethane and chloroform containing varying amounts of water. SEM analyses of the resulting surfaces confirms the strong capacity of NaphDOT to form vertically aligned nanotubes. Polymerization solutions analyzed by DLS and TEM reveal the presence of micelles prior to electropolymerization, and the size of the micelles correlates with the inner diameter of the nanotubes formed. FINDINGS: We show that micelles in polymerization solutions are stabilized by both monomers and electrolytes. We propose a mechanism where reverse micelles are forming a soft-template responsible for the formation of porous nanostructures during electropolymerization in organic, non-polar solvents. In this mechanism, the monomer and electrolyte assume the role of surfactant in the reverse micelle system.