Cold sintering process for fabrication of a superhydrophobic ZnO–polytetrafluoroethylene (PTFE) ceramic composite

Composite coatings or films with polytetrafluoroethylene (PTFE) are typically utilized to offer superhydrophobic surfaces. However, the superhydrophobic surfaces usually have limited durability, and require complicated fabrication methods. Herein, we report the successful integration of PTFE with ZnO ceramic to achieve superhydrophobicity via one-step sintering method, cold sintering process (CSP), at 300 °C. (1-x) ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol% are densified with relative densities of over 97%. Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases, which modulates the surface morphology and surface energy of the ZnO–PTFE ceramic composites. For the 60 vol% ZnO–40 vol% PTFE ceramic composite, the superhydrophobic properties are optimized with static water contact angles (WCA) and sliding angles (SA) of 162^o and 7^o, respectively. After abrading into various thickness (2.52 mm, 2.26 mm and 1.99 mm) and contaminating with graphite powder on the surface, WCA and SA are still maintained with a high level of 157-160^o and 7-9.3^o, respectively. This work indicates that CSP provides a promising pathway to integrate polymer with ceramic to realize stable superhydrophobicity.