多级微结构表面润湿性的尺度效应分析

The size effect analysis of surface wettability on hierarchical structures

多级微结构表面,随着微结构尺度的减小,三相接触线长度的增加,线张力对表观接触角的影响越来越大,引起了研究人员的广泛关注.基于热力学理论,建立考虑线张力影响的多级结构表面接触角理论模型,给出不同状态下接触角的预测公式,具体分析微结构尺寸对多级微结构表面接触角的影响.利用热力学理论及力学平衡分析浸润一级微结构转型所需突破的临界压力及能量势垒,发现在微米尺度下,减小微结构的尺寸不仅可以提高表观接触角,而且能提高浸润转型所需的临界压力和能量势垒,有助于提高润湿稳定性.

On the surface of hierarchical structures,with the decrease of microstructures and the increase of three phase contact line length,the influence of line tension on apparent contact angle becomes higher.Thus,the effect of line tension on surface wettability has attracted widespread attention. Based on thermodynamic theory,the model of apparent contact angle theory with the influence of line tension on hierarchical structures surface is built and the apparent contact angle equations of different wetting states are given. The effect of microstructures size on apparent contact angle is analyzed specificly through the equations. The effect of microstructures size on critical pressure and energy barrier which need to be overcome in the process of wetting transition is analyzed. The results show that the decrease of microstructures size not only can increase the apparent contact angle,but also improve the critical pressure and energy barrier, which is helpful to improve the wetting stability and make a better hydrophobic surface.