Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
Soft Matter. 2018 Nov 21;14(45):9271-9281. doi: 10.1039/c8sm01474d.
A system of binary colloids where one fraction of particles is aggregating by forming irreversible bonds and the other fraction of particles only interacts as hard spheres, is simulated using Brownian cluster dynamics. These aggregating species always formed percolating clusters for the case of diffusing hard spheres while for the static case, formation of percolating clusters depended on the fraction of static hard spheres in the system. The dynamics of the hard spheres inside the percolating clusters was studied by restarting the simulation after the kinetics of aggregation was arrested. Two cases were studied, one where the percolated particles moved within the bonds or cage dynamics was allowed and another where the movement within the bonds was not allowed or the cages were static. The hard spheres showed anomalous diffusion in both cases. The mean square displacement showed that for the case of dynamic cages we always had diffusive hard spheres irrespective of the fraction of hard spheres for volume fractions below 0.49. Static cages, depending on the fraction of hard spheres, showed either diffusive or arrested behavior of hard spheres. The intermediate scattering function of only the hard sphere particles showed double relaxation similar to the colloidal glass system for low volume fraction, where the fraction of hard sphere particles was small. For higher fractions we observed only a single stretched exponential. We could differentiate between slow and fast particles for both static and dynamic cages. For the case of static cages the hard spheres were permanently stuck inside the cages while for the case of dynamic cages almost all the hard spheres were moving in and out of the cages.
使用布朗动力学模拟了一种由两部分胶体组成的体系，其中一部分粒子通过形成不可逆键而聚集，另一部分粒子仅以硬球形式相互作用。对于扩散硬球的情况，这些聚集物种总是形成渗流簇，而对于静态情况，渗流簇的形成取决于系统中静态硬球的分数。通过在聚集动力学停止后重新启动模拟来研究渗流簇内硬球的动力学。研究了两种情况，一种是允许渗流粒子在键内移动或笼动力学，另一种是不允许键内移动或笼是静态的。在这两种情况下，硬球都表现出反常扩散。均方位移表明，对于动态笼的情况，无论体积分数低于 0.49 时硬球的分数如何，我们始终具有扩散硬球。静态笼取决于硬球的分数，表现出扩散或硬球的停滞行为。仅硬球粒子的中间散射函数显示出类似于胶体玻璃系统的双弛豫，其中硬球粒子的分数较小。对于更高的分数，我们只观察到一个单伸展指数。对于静态和动态笼，我们都可以区分慢粒子和快粒子。对于静态笼的情况，硬球被永久卡在笼内，而对于动态笼的情况，几乎所有的硬球都在笼内外移动。
