Wetting transitions on hierarchical surfaces

Abstract

The current study reports the fabrication and characterization of superhydrophobic surfaces with increasing nanoroughness by decreasing silica nanoparticle size in a sol-gel matrix. Using small-angle X-ray scattering (SAXS) measurements allowed for the direct quantification of air entrapped at the interface, revealing for the first time that significant air remains on hierarchical surfaces despite observed droplet pinning through hysteresis measurements. Combining contact angle hysteresis and SAXS measurements of the surfaces immersed in sodium dodecylsulfate (SDS) solutions with Cassie and Tadmor's model, a series of predicted contact angles were generated, comparing wetting transition mech..