Thermo-Responsive Wettability via Surface Roughness Change on Polymer-Coated Titanate Nanorod Brushes Toward Fast and Multi-Directional Droplet Transport

A novel approach for thermo-responsive wettability has been accomplished by surface roughness change induced by thermal expansion of paraffin coated on titanate nanostructures. The surface exhibits thermo-responsive and reversible wettability change in a hydrophobic regime; the surface shows superhydrophobicity with contact angles of ~157° below 50 °C and ~118° above 50 °C due to a decrease of surface roughness caused by thermally-expanded paraffin at higher temperatures. Reversible wettability change of ~40° of a contact angle allows for a fast and multi-directional droplet transport. The present approach affords versatile selection of materials and wide variety of the contact angle, promoting both scientific advancement and technology innovation in the field of smart surface.