Stretchable Hydrophobic Surfaces and Self-Cleaning Applications

Hydrophobizing of stretchable elastomer surfaces is considered and the reversible behavior of the resulting surface wetting state is examined after stretching and relaxing the hydrophobized samples. The environmental dust are analyzed in terms of elemental constitutes and size, and the dust pinning on the hydrophobized surface is measured. The dust removal mechanisms, by the water droplets on the hydrophobized surface, are investigated. We demonstrated that deposition of functionalized nano-size silica units on the elastomer surface gives rise to hydrophobicity with 135 degrees +/- 3 degrees contact angle and low hysteresis of 3 degrees +/- 1 degrees. Stretching hydrophobized elastomer surface by 50% (length) reduces the contact angle to 122 degrees +/- 3 degrees and enhances the hysteresis to 6 degrees +/- 1 degrees. However, relaxing the stretched sample causes exchanging surface wetting state reversibly. Water droplet rolling and sliding can clean the dusty hydrophobized surface almost 95% (mass ratio of the dust particles removed). Droplet puddling causes striations like structures along the droplet path and close examination of the few residues of the dust reveals that the droplet takes away considerably large amount of dust from surface.