超疏水表面液滴的冷凝成长特性研究

Characteristic of Condensed Droplet on the Superhydrophobic Patterned Surface

利用聚二甲基硅氧烷(PDMS)为基底采用光刻技术制备了微方柱状超疏水表面,分析了冷凝条件下超疏水表面液滴的冷凝生长特征,发现液滴的生长过程可分为微液滴成核冷凝独立生长、冷凝微液滴合并生长以及大液滴生长3个阶段。超疏水表面初始合并的液滴呈Wenzel-Cassie状态和Wenzel状态,随着冷凝液滴的成长,液滴的液-固接触面积与粗糙结构表面的表观面积之比f随着冷凝液滴尺寸的增大而增大,Wenzel-Cassie状态向完全Wenzel状态转变。最后分析了超疏水性破坏的原因。

The square-shaped pillars superhydrophobic surfaces were prepared with the polydimethyl -siloxane ( PDMS) sub-strate using photolithography techniques .The growth dynamics of water droplets condensed on a superhydrophobic geometrically patterned surface were studied .Experimental results show that there are three steps during the growing of the water droplets on the superhydrophbic patterned surface at low temperature .The first step is that the small droplets grow lonely .The second step is that the small droplets coalesce and the last step is that the big droplets grow .Furthermore, the droplets on the surface are Wen-zel-Cassie or Wenzel state at first .With increasing of the size of the droplets , the fraction of the solid-liquid contact area and the solid apparent area increases .The Wenzel-Cassie state of the droplets on the superhydrophobic surfaces transform into the Wenzel state when the size of the droplets increase .