Department of Physics and Institute of Biophysics, National Central University, Jhongli 32001, Taiwan.
J Chem Phys. 2010 Aug 28;133(8):084504. doi: 10.1063/1.3474805.
We study the effective electrostatic interactions between a pair of charged colloidal particles without salt ions while the system is confined in two dimensions. In particular, we use a simplified model to elucidate the effects of rotational fluctuations in counterion distribution. The results exhibit effective colloidal attractions under appropriate conditions. Meanwhile, long-range repulsions persist over most of our studied cases. The repulsive forces arise from the fact that in two dimensions, the charged colloids cannot be perfectly screened by counterions, as the residual quadrupole moments contribute to the repulsions at longer range. By applying multiple expansions, we find that the attractive forces observed at short range are mainly contributed by electrostatic interactions among higher-order electric moments. We argue that the scenario for attractive interactions discussed in this work is applicable to systems of charged nanoparticles or colloidal solutions with macroions.
我们研究了在二维限制下一对带电胶体粒子在没有盐离子时的有效静电相互作用。特别地，我们使用简化模型来阐明抗衡离子分布的旋转波动的影响。结果在适当的条件下表现出有效的胶体吸引力。同时，在我们研究的大部分情况下，长程排斥仍然存在。排斥力源于这样一个事实，即在二维空间中，由于带电胶体的剩余四极矩在更远的距离上产生了排斥作用，因此不能被抗衡离子完全屏蔽。通过应用多次展开，我们发现短程观察到的吸引力主要是由高阶电矩之间的静电相互作用贡献的。我们认为，在这项工作中讨论的吸引力相互作用的情况适用于带电荷的纳米粒子或带有大离子的胶体溶液的系统。
