Department of Physics & Astronomy, University of Tennessee , 1408 Circle Drive, Knoxville, Tennessee 37996, United States.
Department of Mathematical Sciences, New Jersey Institute of Technology , Newark, New Jersey 07102, United States.
Langmuir. 2017 Aug 22;33(33):8123-8128. doi: 10.1021/acs.langmuir.7b01655. Epub 2017 Aug 8.
Utilization of the Marangoni effect in a liquid metal is investigated, focusing on initiating instabilities to direct material assembly via the Rayleigh-Plateau instability. Thin (2 nm) copper (Cu) films are lithographically patterned onto thick (12 nm) nickel (Ni) strips to induce a surface energy gradient at the maximum wavelength of the filament instability predicted by Rayleigh-Plateau instability analysis. The pattern is irradiated with an 18 ns pulsed laser such that the pattern melts and the resultant Ni-Cu surface tension gradient induces Marangoni flows due to the difference in surface energies. The experimental results, supported by extensive direct numerical simulations, demonstrate that the Marangoni flow exceeds the capillary flow induced by the initial geometry, guiding instabilities such that final nanoparticle location is directed toward the regions of higher surface energy (Ni regions). Our work shows a route for manipulation, by means of the Marangoni effect, to direct the evolution of the surface instabilities and the resulting pattern formation.
研究了在液态金属中利用 Marangoni 效应通过瑞利-普兰特尔不稳定性引发失稳以直接进行材料组装。通过光刻技术在厚（12nm）镍（Ni）条上图案化薄（2nm）铜（Cu）膜，以在瑞利-普兰特尔不稳定性分析预测的丝状不稳定性的最大波长处诱导表面能梯度。通过 18ns 脉冲激光辐照图案，使图案熔化，由于表面能的差异，导致 Ni-Cu 表面张力梯度诱导 Marangoni 流。实验结果得到广泛的直接数值模拟的支持，证明 Marangoni 流超过由初始几何形状引起的毛细流，引导不稳定性，使得最终纳米颗粒的位置指向具有更高表面能（Ni 区域）的区域。我们的工作表明，通过 Marangoni 效应进行操纵的一种途径，可以指导表面不稳定性的演化和由此产生的图案形成。
