Templateless Electropolymerization for Controlled Growth of Polymeric Nanotubes on Micropatterned Surfaces

Controlling the growth of nanostructures on surfaces is fundamental to develop new materials for various fields of applications such as sensing or biomedical applications. Here, we study for the first time the influence of micropatterned substrates on the growth of nanotubes using a templateless electropolymerization approach. The influence of both the nature of the monomer and the deposition charge used in the polymerization process is assessed along with geometric parameters of the microstructured surfaces composed of bidimensionally distributed squared micropillars. First, we show that the formation of nanotubes is always favored at the basis of the microfeatures rather than on their top surface. As a consequence, it is preferable to avoid using monomers which lead to mono-directional (1D) nanotube growth which would be only generated at the basis of the micropillars. By contrast, monomers leading to extremely short nanotubes (nanocups) are preferred. In addition, we hereby demonstrate that the surface coverage with the nanotubes is highly dependent on the geometric parameters of micropatterned substrates. Indeed, the growth of the nanostructures over the micropillars requires a significant energy and thus micropillars of lower height give optimal results. We demonstrate that it is possible to obtain a complete coverage of the microstructured substrate at even very low deposition charge applied during the electropolymerization step.