Durable superhydrophobic PTFE films through the introduction of micro- and nanostructured pores

A superhydrophobic surface, highly water repellant and self-cleaning, is typically made by introducing micro-and nanoscale roughness onto the surface of a low surface energy material. Herein, we offer a new process of superhydrophobic film formation, accomplishing the same thing through the production of micro-and nanoscale surface porosities. Such a material is prepared by introducing zinc acetate (ZnAc2) and sodium chloride (NaCl) into a commercially available PTFE (polytetrafluoroethylene) emulsion. On drying, baking and washing with acetic acid, the PTFE film produced from the emulsion had both micro and nanoscale surface porosities, and demonstrated superhydrophobic properties, with a static contact angle > 150 degrees and a slide angle < 10 degrees. From SEM observation, NaCl contributes microscale porosity, while ZnAc2 decomposes to ZnO, contributing nanoscale porosity. Using either ZnAc2 or NaCl alone produces a surface with a static contact angle > 150 degrees, but with a slide angle > 10 degrees. Based on XPS and SEM data, we explore herein the affect of chemistry and porosity on the mechanism of superhydrophobic surface formation, and the durability of that surface under abrasion. (C) 2015 Elsevier B.V. All rights reserved.