Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
J Chem Phys. 2011 Jan 21;134(3):034510. doi: 10.1063/1.3525923.
We investigate the combined effects of gravity, attractive interactions, and brownian motion in suspensions of colloidal particles and nonadsorbing polymer. Depending on the effective strength of gravitational forces, resulting from a density mismatch between the colloids and the solvent, and the magnitude and range of the depletion interactions induced by the polymer, sedimentation in these suspensions can result in an equilibrium structure or a kinetically arrested state. We employ large-scale molecular dynamics simulations to systematically classify the different regimes that arise as a function of attraction strength and gravitational stress. Whereas strong attractions lead to cluster aggregation and low-density arrested states, moderate attractions can enhance crystallization of the colloidal particles in the sediment. We make direct comparisons to experimental results to infer general conclusions about the mechanisms leading to mechanically stable sediments.
我们研究了在胶体颗粒和非吸附聚合物的悬浮液中重力、吸引力和布朗运动的综合影响。根据胶体和溶剂之间密度失配产生的有效重力强度，以及聚合物诱导的耗尽相互作用的大小和范围，这些悬浮液中的沉降可能导致平衡结构或动力学停滞状态。我们采用大规模分子动力学模拟，系统地对作为吸引力强度和重力应力函数出现的不同状态进行分类。虽然强烈的吸引力会导致聚集体聚集和低密度停滞状态，但适度的吸引力可以促进沉降中胶体颗粒的结晶。我们直接将实验结果进行比较，以推断出导致机械稳定沉积物的机制的一般结论。
