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 ceramics to achieve superhydrophobicity via a one-step sintering method, cold sintering process (CSP), at 300 ℃. (1–x) ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol% are densified with relative density of over 97%. Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases, which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites. For the 60 vol% ZnO–40 vol% PTFE ceramic composite, superhydrophobic properties are optimized with static water contact angles (WCAs) and sliding angles (SAs) of 162° and 7°, respectively. After abrading into various thicknesses (2.52, 2.26, and 1.99 mm) and contaminating with graphite powders on the surface, WCA and SA are still maintained with a high level of 157°–160° and 7°–9.3°, respectively. This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.