H.H. Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, UK.
Soft Matter. 2017 May 3;13(17):3230-3239. doi: 10.1039/c6sm02221a.
We consider the sedimentation of a colloidal gel under confinement in the direction of gravity. The confinement allows us to compare directly experiments and computer simulations, for the same system size in the vertical direction. The confinement also leads to qualitatively different behaviour compared to bulk systems: in large systems gelation suppresses sedimentation, but for small systems sedimentation is enhanced relative to non-gelling suspensions, although the rate of sedimentation is reduced when the strength of the attraction between the colloids is strong. We map interaction parameters between a model experimental system (observed in real space) and computer simulations. Remarkably, we find that when simulating the system using Brownian dynamics in which hydrodynamic interactions between the particles are neglected, we find that sedimentation occurs on the same timescale as the experiments. An analysis of local structure in the simulations showed similar behaviour to gelation in the absence of gravity.
我们研究了在重力方向受限条件下胶体凝胶的沉降。这种限制使我们能够直接比较实验和计算机模拟，因为在垂直方向上具有相同的系统尺寸。与本体系统相比，这种限制会导致定性不同的行为：在大系统中，凝胶化会抑制沉降，但对于小系统，相对于非胶凝悬浮液，沉降会增强，尽管当胶体之间的吸引力较强时，沉降速度会降低。我们映射了模型实验系统（在实空间中观察到）和计算机模拟之间的相互作用参数。值得注意的是，我们发现当使用忽略粒子间流体动力学相互作用的布朗动力学模拟系统时，我们发现沉降发生的时间尺度与实验相同。对模拟中局部结构的分析表明，在没有重力的情况下，凝胶化具有相似的行为。
