Confined Growth and Controlled Coalescence/Self-Removal of Condensate Microdrops on a Spatially Heterogeneously Patterned Superhydrophilic-Superhydrophobic Surface.

Manipulating condensate nucleation, growth, coalescence, and self-removal via bionic super-wettability surfaces has attracted intensive interest because of their significance in fundamental research and technological innovations, for example, water harvesting, power generation, air conditioning, and thermal management. However, it is still a challenge to simultaneously realize confined growth, coalescence, and self-ejection of condensate microdrops, which has not been reported to date. Here, we propose and demonstrate a type of new and more efficient coalescence/self-removal method based on spatially confined growth/coalescence/self-ejection of condensate microdrops, which can be realized using a rationally designed superhydrophobic surface with spatially heterogeneously patterned superhydrophilic microdots (SMDs). Exemplified by superhydrophobic closely packed zinc oxide nanoneedles with SMD patterns, we investigate how the geometric parameters of SMD patterns be designed to simultaneously realize the spatially confined growth/coalescence/self-ejection of patterned microdrops, which are rationalized via theoretical analyses.