Libet Pavel A, Yakovlev Egor V, Kryuchkov Nikita P, Simkin Ivan V, Sapelkin Andrei V, Yurchenko Stanislav O
Centre for Soft Matter and Physics of Fluids, Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia.
Department of Physics and Astronomy, Queen Mary University of London, London E1 4NS, England.
J Chem Phys. 2024 Jul 28;161(4). doi: 10.1063/5.0210859.
The rotational dynamics of microparticles in liquids have a wide range of applications, including chemical microreactors, biotechnologies, microfluidic devices, tunable heat and mass transfer, and fundamental understanding of chiral active soft matter which refers to systems composed of particles that exhibit a handedness in their rotation, breaking mirror symmetry at the microscopic level. Here, we report on the study of two effects in colloids in rotating electric fields: (i) the rotation of individual colloidal particles in rotating electric field and related to that (ii) precession of pairs of particles. We show that the mechanism responsible for the rotation of individual particles is related to the time lag between the external field applied to the particle and the particle polarization. Using numerical simulations and experiments with silica particles in a water-based solvent, we prove that the observed rotation of particle pairs and triplets is governed by the tunable rotation of individual particles and can be explained and described by the action of hydrodynamic forces. Our findings demonstrate that colloidal suspensions in rotating electric fields, under some conditions, represent a novel class of chiral soft active matter-tunable colloidal spinners. The experiments and the corresponding theoretical framework we developed open novel prospects for future studies of these systems and for their potential applications.
液体中微粒的旋转动力学有着广泛的应用，包括化学微反应器、生物技术、微流控装置、可调热质传递，以及对手性活性软物质的基本理解，手性活性软物质是指由在旋转中呈现手性、在微观层面打破镜像对称的粒子组成的系统。在此，我们报告了对旋转电场中胶体的两种效应的研究：（i）单个胶体粒子在旋转电场中的旋转以及与之相关的（ii）粒子对的进动。我们表明，单个粒子旋转的机制与施加于粒子的外部场和粒子极化之间的时间滞后有关。通过在水基溶剂中对二氧化硅粒子进行数值模拟和实验，我们证明观察到的粒子对和粒子三胞胎的旋转受单个粒子可调旋转的支配，并且可以通过流体动力的作用来解释和描述。我们的研究结果表明，在某些条件下，旋转电场中的胶体悬浮液代表了一类新型的手性软活性物质——可调胶体旋转器。我们开展的实验和相应的理论框架为这些系统的未来研究及其潜在应用开辟了新的前景。
