Fabrication of hierarchical biomimetic polymeric nanostructured surfaces

Abstract

Insect cuticles display complex and often hierarchical surface topographies that control, define, and determine the properties of these surfaces. The structural hierarchy that is displayed by insect cuticles extends from the micron scale to the nanoscale and often results in multimodal functionality, simultaneously generating mechanical properties such as self-cleaning and antimicrobial activity and optical properties such as structural color or anti-reflection. The native nanostructured surfaces (NSS) that are found on insect cuticles are the product of cellular mechanisms and composed of protein, chitin, and lipids. These cellular processes generate surfaces with high uniformity and reproducibility, but on a minute scale such as the surface of wings or eyes. We show that by modification of the nanosphere lithographic technique through the use of different substrates, alteration to the etching conditions, and reiteration of the nanosphere lithographic process itself, we can fabricate biomimetic surfaces that mimic the nanoscale hierarchies found on native insect cuticles and generate new and novel hierarchical NSS. Synthetic NSS display tunable wettability and interesting spectral properties, which demonstrates that the generation of biomimetic synthetic nanostructured surfaces via NSL holds great promise for many applications including solar energy, optics, and antimicrobial surfaces.