Controlling macroscopic interfacial behaviors such as adhesion and wettability requires precise structuring and spacing of microscale and nanoscale features across a surface. As an example, densely packed nanofibers across a gecko’s foot have been cited as the driving force for the remarkable adhesion observed between gecko feet and solid substrates, enabling geckos to walk in a completely inverted state. The van der Waal’s force acting between each individual fiber and the surface with which they are in contact with contributes to the unexpectedly strong adhesion. Taking the gecko as inspiration, surfaces with robust features of similar shape and distribution (including nanofibers, nanotubes, and nanofilaments) have been a subject of significant research. Unfortunately, without a template or support to direct the formation of such features, it is difficult to create regular, well-defined and free-standing nanoscale mimics of the gecko toepad. Here we show that vertically-aligned, well-ordered nanotube features can be developed on a surface via electrodeposition of 3,4-phenylenedioxythiophene (PhEDOT) monomers, using a template-free and unsupported method. In this process, trace water present in solution is sufficient to induce the formation of gas bubbles (O2 and H2 gas depending on the electropolymerization method). Substitution of the PhEDOT monomer structure (with alkyl and aromatic units) leads to variable stabilization of the gas bubbles, and as a consequence variable polymer growth around them creating nanotube features. Beyond the demonstration of successful nanotube formation, we demonstrate that the spacing, density, and distribution of these features can be varied by simple modification of the electropolymerization protocol (scan rate, solvent, etc.), and how these modifications influence surface wettability and water adhesion. This demonstration of direct formation of nanotube features is particularly relevant, as the elaboration of surfaces without the use of excess material (templates, supports) is necessary for large-scale applications in anti-corrosion, anti-biofouling, anti-fog, and directed adhesion.

Nanotube decorated interfaces via template-less, electropolymerization of thiophene-based monomers

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.