Khan Mohammad Rashed, Eaker Collin B, Bowden Edmond F, Dickey Michael D
Departments of Chemical and Biomolecular Engineering and.
Chemistry, North Carolina State University, Raleigh, NC 27695.
Proc Natl Acad Sci U S A. 2014 Sep 30;111(39):14047-51. doi: 10.1073/pnas.1412227111. Epub 2014 Sep 16.
We present a method to control the interfacial tension of a liquid alloy of gallium via electrochemical deposition (or removal) of the oxide layer on its surface. In sharp contrast with conventional surfactants, this method provides unprecedented lowering of surface tension (∼ 500 mJ/m(2) to near zero) using very low voltage, and the change is completely reversible. This dramatic change in the interfacial tension enables a variety of electrohydrodynamic phenomena. The ability to manipulate the interfacial properties of the metal promises rich opportunities in shape-reconfigurable metallic components in electronic, electromagnetic, and microfluidic devices without the use of toxic mercury. This work suggests that the wetting properties of surface oxides--which are ubiquitous on most metals and semiconductors--are intrinsic "surfactants." The inherent asymmetric nature of the surface coupled with the ability to actively manipulate its energetics is expected to have important applications in electrohydrodynamics, composites, and melt processing of oxide-forming materials.
我们提出了一种通过电化学沉积（或去除）镓液态合金表面的氧化层来控制其界面张力的方法。与传统表面活性剂形成鲜明对比的是，该方法使用非常低的电压就能实现前所未有的表面张力降低（从约500 mJ/m²降至接近零），并且这种变化是完全可逆的。界面张力的这种显著变化能够引发各种电流体动力学现象。操控金属界面性质的能力为电子、电磁和微流体设备中可形状重构的金属部件带来了丰富的机遇，且无需使用有毒的汞。这项工作表明，在大多数金属和半导体上普遍存在的表面氧化物的润湿性是固有的“表面活性剂”。表面固有的不对称性质以及主动操控其能量学的能力有望在电流体动力学、复合材料和氧化物形成材料的熔体加工中具有重要应用。
