Influence of engineering environment on wetting properties and long-term stability of a superhydrophobic polymer coating

Surface behaviors of superhydrophobic polymer coating applied in severe engineering environment are firstly systematically investigated. The PTFE/PPS (Polytetrafluoroethylene/Polyphenylene sulfide) coating still possess good superhydrophobicity after natural ice and snow covering for 10 day due to its micrometer-nanometer-scale binary structure (MNBS) with long-term stability. Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle (WCA) are used to characterize the morphology, chemical components and wetting properties of the coating, respectively. Surprisingly, the PTFE nano-fibers on most micro-scale papillae of the original coating were "chemical-etched" and then "secondary-constructed" to form nano-spheres/papules by H2SO4 under "accelerated simulated acid rain" condition (pH = 0.3). It is firstly found that chemical-etching by simulated acid rain only result in the "secondary-construction" of MNBS structure. However, the laboratory weathering tests indicated that light-etching by the light with specified wavelength (UV, about 300-400 nm) can lead to both the "secondary-construction" of MNBS structure and the change of surface chemical composition/groups on the superhydrophobic coatings. This thesis clarifies the long-term stability and surface behaviors of the superhydrophobic polymer coating under severe engineering condition, and will provide significant theoretical guidance for superhydrophobic polymer coating as anti-ice/frost engineering material.