Handschuh-Wang Stephan, Zhu Lifei, Gan Tiansheng, Wang Tao
College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518055, China.
Functional Thin Films Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
Materials (Basel). 2020 May 15;13(10):2283. doi: 10.3390/ma13102283.
The liquid metal lyophobicity of a rough substrate was, in previous articles, found to be rather independent on the surface wettability. In this article, we scrutinize the impact of surface wettability of a structured (rough) surface on the liquid metal wettability and adhesion. As a model system, a structured diamond coating was synthesized and modified by air plasma. We show that surface wettability (surface free energy) does not play a prominent role for static contact angle measurements and for the liquid metal repelling properties of the diamond coating in droplet impact experiments. In contrast, roll off angles and repeated deposition experiments illustrate that the increased hydrophilicity impacts the long-term liquid metal repellency of our coating. Liquid metal adhered after around 50 deposition/removal cycles on the hydrophilic diamond coating, while no liquid metal adhesion was visible after 100 cycles on the hydrophobic diamond coating, illustrating the fundamental role for the adhesion of liquid metal. The effect of repeated deposition in conjunction with gentle applied force was employed for coating the liquid metal lyophobic (hydrophilic) diamond coating with a thin liquid metal layer. The observed effect may find application in flexible electronics and thermal management systems as a means to improve interfacing of the liquid metal with conductive non-metal coatings.
在之前的文章中发现，粗糙基底的液态金属疏液性在很大程度上与表面润湿性无关。在本文中，我们仔细研究了结构化（粗糙）表面的表面润湿性对液态金属润湿性和附着力的影响。作为一个模型系统，合成了一种结构化金刚石涂层并用空气等离子体对其进行改性。我们表明，表面润湿性（表面自由能）在静态接触角测量以及液滴冲击实验中金刚石涂层的液态金属排斥性能方面并不起显著作用。相比之下，滚落角和重复沉积实验表明，亲水性的增加会影响我们涂层的长期液态金属排斥性。在亲水性金刚石涂层上经过约50次沉积/去除循环后液态金属会附着，而在疏水性金刚石涂层上经过100次循环后仍未见液态金属附着，这说明了其对液态金属附着力的重要作用。结合轻柔施加的力进行重复沉积的效果被用于在液态金属疏液（亲水）金刚石涂层上涂覆一层薄的液态金属层。观察到的这种效果可能在柔性电子和热管理系统中得到应用，作为一种改善液态金属与导电非金属涂层界面结合的手段。
