Stamou D, Duschl C, Johannsmann D
Laboratoire de Chimie Physique des Polymeres et Membranes, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Oct;62(4 Pt B):5263-72. doi: 10.1103/physreve.62.5263.
Recent observations of charged colloidal particles trapped at the air-water interface revealed long-range interparticle attractive forces, not accounted for by the standard theories of colloidal interactions. We propose a mechanism for attraction which is based on nonuniform wetting causing an irregular shape of the particle meniscus. The excess water surface area created by these distortions can be minimized when two adjacent particles assume an optimum relative orientation and distance. Typically, for spheres with diameter of 1 &mgr;m at an interparticle distance of 2 &mgr;m, deviations from the ideal contact line by as little as 50 nm result in an interaction energy of the order of 10(4)kT. Roughness-induced capillarity explains the experimental findings, including the cluster dissolution caused by addition of detergent to the subphase and the formation of linear aggregates. This kind of interaction should also be of importance in particle-stabilized foams and emulsions.
最近对被困在空气 - 水界面的带电胶体颗粒的观察揭示了粒子间的长程吸引力，这是标准胶体相互作用理论无法解释的。我们提出了一种基于不均匀润湿导致颗粒弯月面形状不规则的吸引机制。当两个相邻颗粒处于最佳相对取向和距离时，由这些变形产生的多余水表面积可以最小化。通常，对于直径为1μm的球体，在颗粒间距离为2μm时，与理想接触线的偏差小至50nm会导致相互作用能达到10⁴kT量级。粗糙度诱导的毛细作用解释了实验结果，包括向亚相添加洗涤剂导致的聚集体溶解和线性聚集体的形成。这种相互作用在颗粒稳定的泡沫和乳液中也应该很重要。
