Comparative study of the impact and sliding behavior of water droplets on two different hydrophobic silane coatings

Smooth hydrophobic silane coatings were prepared on a Si substrate using ODS (CH3(CH2)(17)Si(OCH3)(3) and FAS17 (CF3(CF2)(7)(CH2)(2)Si(OCH3)(3)). Results obtained using ellipsometry and Kelvin force microscopy suggest that ODS molecules in the coating are tilting or inflected, whereas those of FAS17 are more normal to the substrate. Impact and sliding behaviors of water droplets on the respective surfaces were investigated using a 15 mu L water droplet by varying the droplet release height. Droplets on ODS slid down faster than on FAS17 when released from 0 mm height (i.e. traditional dynamic hydrophobicity measurement). The order was reversed when providing the impact velocity. Comparison of energy dissipation during the impact process revealed that the droplet on ODS, because of its large deformation, loses more energy than that on FAS17. These results demonstrate that the order of droplet removal performance depends on the presence or absence of some initial velocity. (C) 2013 Elsevier B.V. All rights reserved.

使用十八烷基三甲氧基硅烷（ODS，CH₃(CH₂)₁₇Si(OCH₃)₃）和十七氟癸基三甲氧基硅烷（FAS17，CF₃(CF₂)₇(CH₂)₂Si(OCH₃)₃）在硅基底上制备了光滑的疏水硅烷涂层。利用椭圆偏振仪和开尔文力显微镜获得的结果表明，涂层中的ODS分子倾斜或弯曲，而FAS17分子则更垂直于基底。通过改变液滴释放高度，使用15微升水滴研究了水滴在各自表面上的撞击和滑动行为。当从0毫米高度释放时（即传统的动态疏水性测量），ODS上的水滴比FAS17上的水滴下滑得更快。当提供撞击速度时，情况则相反。对撞击过程中能量耗散的比较表明，由于ODS上的水滴变形较大，其比FAS17上的水滴损失更多能量。这些结果表明，水滴去除性能的顺序取决于是否存在一些初始速度。© 2013爱思唯尔有限公司。保留所有权利。