Preparation And Icing Behavior Of RTV Based Composites With Surface Superhydrophobicity

Three typical superhydrophobic surfaces based on RTV composites, i.e., ZnO/RTV, PTFE/RTV and Cu/RTV composites, were prepared using ZnO, polytetrafluoroethylene(PTFE) and Cu powders as filler respectively and room temperature vulcanized silicon rubber(RTV) as polymer matrix via different methods. The ZnO particles were first modified with hydrophobic reagent and then mixed with RTVsolution. After cured at room temperature and followed by abrading with sandpaper, the superhydrophobic surfaces based on ZnO/RTV composites were obtained. The PTFE particles were dispersed on the surface of RTV solution by using a mesh(mesh number is 200). The PTFE particles sunk slowly in the RTV solution. After cured at room temperature, the PTFE/RTV composite was obtained. Similarly, the Cu/RTV composite was prepared by uniformly spreading Cu poders on the surface of RTV solution in the process of solidification. The as-prepared Cu/RTV composite was immersed in AgNO3 solution to generate a rough layer of silver on the surface of Cu/RTV composite. Finally, the Ag/RTV composite was modified with perfluorinated decyl mercaptan to fabricate a superhydrophobic surface of Ag/RTV composite.The surface morphology, chemical composition, mechanical stability and icing behavior of the as-prepared superhydrophobic surface based on ZnO/RTV, PTFE/RTV and Ag/RTV composites were system studied. The results indicate that the hydrophobic ZnO particles were obtained by surface modification with n-dodecanethiol in the solution of ethanol. The superhydrophobic surface of ZnO/RTV composite containing 40 wt. % of ZnO was fabricate by abrading the surface with 400# sandpaper. The static contact angle was 165° and sliding angle was 5.1°. The superhydrophobic surface of ZnO/RTV composite could delay ice formation for a delay time of 24 min at-8 °C under the experimental condition, i.e., at an environment temperature of 25 °C, at a relative air humidity of 63%. The superhydrophobicicy of the PTFE/RTV composite was stable after pressed by a finger, brushed repeatedly by a tube brush and impacting of sand particles, which demonstrated the excellent stabilities against pressing and abrading. The icing behavior of the superhydrophobic surface of the as-prepared PTFE/RTV composite, as well as the surface of a pure Al sheet(for comparison), was studied under a home-made ice-formation condition. It was observed that the superhydrophobic PTFE/RTV composite surface could prevent ice from accretion on the surface among the mearsuring time of 30 min. The Ag/RTV composite exhibited a high static contact angle of 168.7° and a low sliding of 3.7° after fluoridization. The superhydrophobic surface of Ag/RTV composite was mechanical robust against finger touch and repeatedly brushing with hard brush. In addition, the superhydrophobic surface of Ag/RTV composite showed low temperature self-cleaning properties at a temperature of-10 °C when the surface was tilted at 10°.