Stability of Superhydrophobicity of Lotus Leaf under Extreme Humidity

We systematically evaluated water contact and sliding angles on the lotus leaf from -10 to 80 degrees C under either extremely low or high relative humidity. SEM images revealed changes of the hierarchical structures after thermal treatment at different temperatures. The wettability recovery test showed consistent results that a restorable loss of superhydrophobic behavior appeared under low temperature and high humidity due to water condensation, whereas structural destruction at high temperatures caused the lotus leaf to lose extraordinary water repellency permanently.