微结构超疏水表面：压降对fakir态稳定性和表观接触角的影响
Microstructured superhydrorepellent surfaces: Effect of drop pressure on fakir-state stability and apparent contact angles
摘要：
在本文中，我们提出了一个广义的Cassi-Baxter方程，以考虑压降对表观接触角theta_{app}的影响。此外，我们确定的极限压力p_{W}，导致穿刺过渡到Wenzel状态和拉脱压力p_{out}，在该液滴脱离基板。计算了三种不同形状的轴对称柱：圆锥形，半球形和平顶圆柱形柱。计算表明，假设相同的柱间距，锥形柱可能更倾向于经历穿刺过渡到Wenzel状态，但是，另一方面，它们的特征在于消失的拉脱压力，这导致液滴不粘附到衬底上，因此非常容易分离。我们推断，这一性质将大大降低接触角滞后，正如在参考文献\cite{Martines-Conical-Shape}中实验观察到的那样。通过采用具有圆锥形尖端的圆柱形柱，可以将对刺穿过渡的大阻力（即，大的p_{W}值）和小的（或甚至消失的）分离压力p_{out}相结合。我们还表明，取决于特定的支柱几何形状，压降对表观接触角theta_{app}的影响可能或多或少显着。特别是，我们表明，在圆锥形支柱的情况下，增加压降导致theta_{app}的显着减少与一些实验研究\cite{LafunaTransitio}，而theta_{app}略有增加半球形或平顶圆柱形支柱。
英文摘要：
In this paper we present a generalized Cassi-Baxter equation to take into account the effect of drop pressure on the apparent contact angle theta_{app}. Also we determine the limiting pressure p_{W} which causes the impalement transition to the Wenzel state and the pull-off pressure p_{out} at which the drop detaches from the substrate. The calculations have been carried out for axial-symmetric pillars of three different shapes: conical, hemispherical topped and flat topped cylindrical pillars. Calculations show that, assuming the same pillar spacing, conical pillars may be more incline to undergo an impalement transition to the Wenzel state, but, on the other hand, they are characterized by a vanishing pull-off pressure which causes the drop not to adhere to the substrate and therefore to detach very easily. We infer that this property should strongly reduce the contact angle hysteresis as experimentally osberved in Ref. \cite{Martines-Conical-Shape}. It is possible to combine large resistance to impalement transition (i.e. large value of p_{W}) and small (or even vanishing) detaching pressure p_{out} by employing cylindrical pillars with conical tips. We also show that depending on the particular pillar geometry, the effect of drop pressure on the apparent contact angle theta_{app} may be more or less significant. In particular we show that in case of conical pillars increasing the drop pressure causes a significant decrease of theta_{app} in agreement with some experimental investigations \cite{LafunaTransitio}, whereas theta_{app} slightly increases for hemispherical or flat topped cylindrical pillars.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
