Lubricant-infused textured solid substrates are gaining remarkable interest as a new class of omni-repellent nonfouling materials and surface coatings. We investigated the effect of the length scale and hierarchy of the surface topography of the underlying substrates on their ability to retain the lubricant under high shear conditions, which is important for maintaining nonwetting properties under application-relevant conditions. By comparing the lubricant loss, contact angle hysteresis, and sliding angles for water and ethanol droplets on flat, microscale, nanoscale, and hierarchically textured surfaces subjected to various spinning rates (from 100 to 10 000 rpm), we show that lubricant-infused textured surfaces with uniform nanofeatures provide the most shear-tolerant liquid-repellent behavior, unlike lotus leaf-inspired superhydrophobic surfaces, which generally favor hierarchical structures for improved pressure stability and low contact angle hysteresis. On the basis of these findings, we present generalized, low-cost, and scalable methods to manufacture uniform or regionally patterned nanotextured coatings on arbitrary materials and complex shapes. After functionalization and lubrication, these coatings show robust, shear-tolerant omniphobic behavior, transparency, and nonfouling properties against highly contaminating media.
This research was supported by the ONR under the awards #N00014-12-1-0962 (fabrication of non- fouling surfaces on various materials), #N00014-12-1-0875 (shear-dependent behavior) and AFOSR under the award #FA9550-09-1-0669-DOD35CAP (optical properties). Part of this work was performed at the Centre for Nanoscale Systems (CNS) at Harvard University, supported under NSF award #ECS- 0335765. We thank Honeywell-Sperian for providing polycarbonate lens samples, FLEXcon for providing aluminized PET sheet samples. We thank Mr Onye Ahanotu for SEM images of sandblasted aluminum and pictures of aluminized plastic films, and Dr Alison Grinthal and Mr Noah McCallum for providing comments on the manuscript.