UVO Tunable Superhydrophobic to Superhydrophilic Wetting Tranistion on Biomimetic Nanostructured Surfaces
Joong T. Han, Sangcheol Kim, Alamgir Karim
We present a tunable sigmoidal wetting transition from superhydrophobicity (CA > 170o) to superhydrophilicity (CA < 10o) on a single nanostructured hybrid film prepared from layer-by-layer assembled negatively charged silica nanoparticles (11 nm) and a positively charged poly(allylamine hydrochloride) via gradient UV-Ozone exposure of the superhydrophobic surface. The wetting transition behavior is dependent on submicro scale roughness and pores generated by increasing the number of nanoparticle layers. This extraordinary wetting transition represents a novel competition between roughness and chemical modification of surfaces.