Temperature and humidity effects on superhydrophobicity of nanocomposite coatings

This work investigates temperature and humidity effects on the superhydrophobicity of polyurethane/organoclay nanocomposites. Previous reports of superhydrophobic degradation at decreasing surface temperatures for both low and high humidity were generally conducted in open environments. However, the present setup allows a thermally homogeneous environment, i.e., the temperature of the nanocomposite, air and water droplet are equal with no spatial temperature gradients. In such conditions, results showed stable retention of superhydrophobicity for both low humidity (RH < 20%) cool-down and warm-up cycles (20 degrees C to -3 degrees C to 20 degrees C). Similar performance was also observed for a high humidity (RH > 80%) cool-down cycle, though superhydrophobicity degraded during the warm-up cycle, which was attributed to dew condensation. (C) 2012 American Institute of Physics. [doi:10.1063/1.3680567]