School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
Langmuir. 2012 Mar 13;28(10):4793-9. doi: 10.1021/la300416x. Epub 2012 Mar 2.
This article experimentally shows that the wetting property of a micropatterned surface is a function of the center-to-center offset distance between successive pillars in a column, referred to here as eccentricity. Studies were conducted on square micropatterns which were fabricated on a silicon wafer with pillar eccentricity ranging from 0 to 6 μm for two different pillar diameters and spacing. Measurement results of the static as well as the dynamic contact angles on these surfaces revealed that the contact angle decreases with increasing eccentricity and increasing relative spacing between the pillars. Furthermore, quantification of the contact angle hysteresis (CAH) shows that, for the case of lower pillar spacing, CAH could increase up to 41%, whereas for the case of higher pillar spacing, this increment was up to 35%, both corresponding to the maximum eccentricity of 6 μm. In general, the maximum obtainable hydrophobicity corresponds to micropillars with zero eccentricity. As the pillar relative spacing decreases, the effect of eccentricity on hydrophobicity becomes more pronounced. The dependence of the wettability conditions of the micropatterned surface on the pillar eccentricity is attributed to the contact line deformation resulting from the changed orientation of the pillars. This finding provides additional insights in design and fabrication of efficient micropatterned surfaces with controlled wetting properties.
本文通过实验表明，微图案表面的润湿性是相邻支柱中心到中心偏移距离（这里称为偏心距）的函数。研究对象是在硅晶片上制造的正方形微图案，其支柱偏心距在 0 到 6μm 之间变化，针对两种不同的支柱直径和间距进行了研究。对这些表面的静态和动态接触角的测量结果表明，接触角随偏心距的增加和支柱之间相对间距的增加而减小。此外，对接触角滞后（CAH）的量化表明，对于较低的支柱间距，CAH 可增加高达 41%，而对于较高的支柱间距，CAH 可增加高达 35%，这两种情况均对应于最大偏心距 6μm。通常，最大可得疏水性对应于具有零偏心距的微支柱。随着支柱相对间距的减小，偏心距对疏水性的影响变得更加明显。微图案表面润湿性条件对支柱偏心距的依赖性归因于由于支柱取向变化而导致的接触线变形。这一发现为设计和制造具有可控润湿性的高效微图案表面提供了更多的见解。
