E. Kujan, B. Farshchian, Q. Xu, M. Feldman, A. Lyons
ARL Designs LLC, United States
pp. 502 - 505
Keywords: superhydrophobicity, self-cleaning, roofing, green, EPDM, nitrile, rubber, silicone
Polymeric materials with superhydrophobic surfaces are advantageous for industrial applications such as electrical insulators, roof membranes and seals because their surfaces are self-cleaning and remain dry when exposed to rain. However most superhydrophobic surfaces are fragile and can wet in rain or when submerged in water. We have developed a robust method for treating commercial thermosetting elastomers to render their surfaces superhydrophobic. Two tests were developed to quantify the stability of superhydrophobic surfaces: resistance to rain-induced erosion and stability under continuous immersion. Commercial elastomers, with different chemical and mechanical properties, were rendered superhydrophobic. Simulated rain was generated using UL-50 nozzle; droplets were characterized using a high speed camera; time to wetting was recorded. Inspection of surfaces showed progressive changes to the surface topography; erosion rates varied depending upon elastomer properties. To assess the stability under water, a 1-meter immersion test conforming to IEC60529-IPX7-8 was built. The persistence of the air layer trapped between the water and elastomer (i.e. plastron) was measured for several materials. All materials surpassed the 0.5 hour IPX7-8 standard and several endured for weeks. Discussion of the surface and material characteristics that affect superhydrophobic performance is provided.