Peng Xiaolei, Lin Linhan, Hill Eric H, Kunal Pranaw, Humphrey Simon M, Zheng Yuebing
Materials Science & Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712, USA.
Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
J Phys Chem C Nanomater Interfaces. 2018 Oct 25;122(42):24226-24234. doi: 10.1021/acs.jpcc.8b03828. Epub 2018 Jun 1.
The response of colloidal particles to a light-controlled external temperature field can be harnessed for opto-thermophoretic manipulation of the particles. The thermoelectric effect is regarded as the driving force for thermophoretic trapping of particles at the light-irradiated hot region, which is thus limited to ionic liquids. Herein, we achieve opto-thermophoretic manipulation of colloidal particles in various non-ionic liquids, including water, ethanol, isopropyl alcohol and 1-butanol, and establish the physical mechanism of the manipulation at the molecular level. We reveal that the non-ionic driving force originates from a layered structure of solvent molecules at the particle-solvent interface, which is supported by molecular dynamics simulations. Furthermore, the effects of hydrophilicity, solvent type, and ionic strength on the layered interfacial structures and thus the trapping stability of particles are investigated, providing molecular-level insight into thermophoresis and guidance on interfacial engineering for optothermal manipulation.
胶体颗粒对光控外部温度场的响应可用于对颗粒进行光热泳操控。热电效应被视为颗粒在光照射的热区进行热泳捕获的驱动力，因此这种效应仅限于离子液体。在此，我们实现了在包括水、乙醇、异丙醇和正丁醇在内的各种非离子液体中对胶体颗粒的光热泳操控，并在分子水平上建立了操控的物理机制。我们揭示了非离子驱动力源自颗粒 - 溶剂界面处溶剂分子的层状结构，这一结论得到了分子动力学模拟的支持。此外，还研究了亲水性、溶剂类型和离子强度对层状界面结构以及颗粒捕获稳定性的影响，为热泳提供了分子水平的见解，并为光热操控的界面工程提供了指导。
