Versatile fabrication and applications of dense, orderly arrays of polymeric nanostructures over large areas

Abstract

Dense arrays of nanostructures were fabricated in polymer surfaces over large areas (1 cm × 1 cm) using laser interference lithography and low power CF₄/O₂ plasma etching. The dependence of the etch rate and etch anisotropy on plasma composition was studied in detail for polystyrene and 4 distinct regimes were identified. In each of these regimes, the polystyrene nanostructures exhibit characteristic variations of etch rate, etch anisotropy and surface chemistry that were found to be closely related to the level of fluorination and polymerization on the substrate surface. A new technique, stitch etching, was developed and utilized in conjunction with low power plasma etching to increase the height of nanostructures without loss of array density. These nanofabrication techniques are shown to be versatile enough to be applied to a variety of polymers. The polymeric nanostructures were found to exhibit a number of useful properties including superhydrophobicity (directional effect, lotus leaf effect and rose petal effect), structural stiffness and biocompatibility, which were shown to be useful in applications such as self-cleaning surfaces, nanoimprinting molds and biocompatible substrates for neurite guidance.