Confined Growth and Controlled Coalescence/Self-Removal of Condensate Microdrops on 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 researches and technological innovations, e.g., 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 up to now. Here, we propose and demonstrate a type of new and more efficient coalescence/self-removal way based on spatially-confined growth/coalescence/self-ejection of condensate microdrops, which can be realized by 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 design to simultaneously realize the spatially confined growth/coalescence/self-ejection of patterned microdrops, which are rationalized via theoretical analyses.