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Gecko-like Branched Polymeric Nanostructures from Nanoporous Templates

Blaszczyk-Lezak, Iwona, Juanes, Diana, Martín, Jaime, Mijangos, Carmen
Langmuir 2018 v.34 no.38 pp. 11449-11453
Gekkonidae, adhesion, aluminum oxide, biomimetics, crystal structure, nanopores, nanowires, phase transition, polymers, texture
Here, we report a simple method to produce hierarchically shaped polymeric one-dimensional nanostructures. More specifically, dual-sized polymer nanowires are fabricated employing multibranched anodic aluminum oxide templates. By fine selection of the anodization conditions, we achieve branched nanopores having a first segment of 400 nm in diameter from which seven further 55 nm in diameter pores arise. Wetting of such nanopores with polymer melts—for example, poly(ε-caprolactone) and polystyrene—allows for the nanomolding of their respective inverse nanostructures, that is, dual-sized multibranched polymer nanowires that, when supported on a flat surface, strongly resemble the spatulae of geckos’ toes. The structural features of the dual-sized polymer nanostructures, namely, crystalline phase, crystallinity, texture, and so on, are furthermore characterized and interpreted within the context of polymer phase transitions in confined media. Our work presents a readily applicable approach to produce soft nanomaterials of high morphological complexity, thereby with promising implications in the nanotechnology area, for example, in biomimetic solid adhesion.