Agrawal Nikhil R, Kaur Ravtej, Carraro Carlo, Wang Rui
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA.
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
J Chem Phys. 2023 Dec 28;159(24). doi: 10.1063/5.0181061.
The electrostatic double layer force is key to determining the stability and self-assembly of charged colloids and many other soft matter systems. Fully understanding the attractive force between two like-charged surfaces remains a great challenge. Here, we apply the modified Gaussian renormalized fluctuation theory to study ion correlation-driven like-charge attraction in multivalent salt solutions. The effects of spatially varying ion correlations on the structure of overlapping double layers and their free energy are self-consistently accounted for. In the presence of multivalent salts, increasing surface charge or counterion valency leads to a short-range attraction. We demonstrate that although both overcharging and like-charge attraction are outcomes of ion correlation, there is no causal relationship between them. Our theory also captures the non-monotonic dependence of like-charge attraction on multivalent salt concentration. The reduction of attraction at high salt concentrations could be a contributing factor toward the reentrant stability of charged colloidal suspensions. Our theoretical predictions are consistent with the observations reported in experiments and simulations.
静电双层力是决定带电胶体和许多其他软物质系统稳定性和自组装的关键因素。全面理解两个同性带电表面之间的吸引力仍然是一个巨大的挑战。在此，我们应用修正的高斯重整化涨落理论来研究多价盐溶液中离子关联驱动的同性电荷吸引。空间变化的离子关联对重叠双层结构及其自由能的影响得到了自洽考虑。在多价盐存在的情况下，增加表面电荷或反离子价态会导致短程吸引。我们证明，尽管过充电和同性电荷吸引都是离子关联的结果，但它们之间不存在因果关系。我们的理论还捕捉到了同性电荷吸引对多价盐浓度的非单调依赖性。高盐浓度下吸引力的降低可能是带电胶体悬浮液重入稳定性的一个促成因素。我们的理论预测与实验和模拟中报道的观察结果一致。
