Switchable Wettability for Condensation Heat Transfer.

Condensation proceeds as dropwise or filmwise depending on the wettability of the condensing surface. These two modes of condensation have disparate heat transfer coefficients, with dropwise often exceeding filmwise. This work reports a surface with switchable superhydrophilic to hydrophobic wetting behavior that can exhibit both modes of condensation. Relative to the highly wetting state, which yields filmwise condensation, the nonwetting state exhibits dropwise condensation and twice the heat transfer coefficient. Relevance to thermal management is additionally discussed.