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

Abstract

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.

Bioinspired materials for droplet manipulation: Principles, methods and applications

“…Light fields, electric fields and magnetic fields, as well as other external stimuli such as thermal fields, 34,78,107,122 pH value gradients 33,123 and mechanical vibrations 111 have been used to manipulate droplets. Banuprasad et al 124 reported on a method for rapid droplet transport over a poly (N-isopropyl acrylamide) (ii) droplet carrying on climbing movement on the bridge-like magnetic droplet microfluidic platform (MDMP), under the control of magnetic probe.…”