Hessberger Tristan, Braun Lukas B, Serra Christophe A, Zentel Rudolf
Department of Organic Chemistry, Johannes Gutenberg University.
CNRS, ICS UPR 22, Université de Strasbourg.
J Vis Exp. 2018 May 20(135):57715. doi: 10.3791/57715.
This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation usually consists in the formation of droplets containing low molar mass liquid crystals at elevated temperatures. Subsequently, these particle precursors are oriented in the flow field of the capillary and solidified by a crosslinking polymerization, which produces the final actuating particles. The optimization of the process is necessary to obtain the actuating particles and the proper variation of the process parameters (temperature and flow rate) and allows variations of size and shape (from oblate to strongly prolate morphologies) as well as the magnitude of actuation. In addition, it is possible to vary the type of actuation from elongation to contraction depending on the director profile induced to the droplets during the flow in the capillary, which again depends on the microfluidic process and its parameters. Furthermore, particles of more complex shapes, like core-shell structures or Janus particles, can be prepared by adjusting the setup. By the variation of the chemical structure and the mode of crosslinking (solidification) of the liquid crystalline elastomer, it is also possible to prepare actuating particles triggered by heat or UV-vis irradiation.
本文聚焦于从液晶弹性体制备驱动颗粒的微流控过程（及其参数）。制备过程通常包括在高温下形成含有低摩尔质量液晶的液滴。随后，这些颗粒前体在毛细管的流场中取向，并通过交联聚合固化，从而产生最终的驱动颗粒。该过程的优化对于获得驱动颗粒以及合理改变过程参数（温度和流速）是必要的，并且允许颗粒尺寸和形状（从扁球形到强烈的长球形形态）以及驱动幅度发生变化。此外，根据在毛细管中流动期间施加到液滴上的指向矢分布，有可能改变驱动类型，从伸长到收缩，而这又取决于微流控过程及其参数。此外，通过调整装置，可以制备更复杂形状的颗粒，如核壳结构或Janus颗粒。通过改变液晶弹性体的化学结构和交联（固化）方式，还可以制备由热或紫外 - 可见辐射触发的驱动颗粒。
