nl4003969_si_008.mpg (37.98 MB)
Hierarchical or Not? Effect of the Length Scale and Hierarchy of the Surface Roughness on Omniphobicity of Lubricant-Infused Substrates
media
posted on 2016-02-19, 12:32 authored by Philseok Kim, Michael J. Kreder, Jack Alvarenga, Joanna AizenbergLubricant-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.