不同力程排斥相互作用胶体粒子系统的摩擦特性

Friction characteristics of colloidal particle systems with repulsive interactions of different force ranges

利用朗之万分子动力学,数值研究了无序点钉扎衬底上二维胶体粒子系统的摩擦特性.本文考虑了三种不同的模型胶体粒子系统,每种系统中胶体粒子之间的相互作用均被模拟为两种不同力程的排斥势.研究发现:每种模型系统均存在两个最大静摩擦力(第一最大静摩擦力f_(c1)^(d)和第二最大静摩擦力f_(c2)^(d));力程相近的短程排斥相互作用之间的干涉会导致粒子间排斥增强,从而导致f_(c1)^(d)的明显降低和f_(c2)^(d)以上沿外场驱动力方向上运动有序的加强.本文的研究结果有助于揭示具有不同力程相互作用胶体粒子系统的摩擦机制.

Friction occurs in various systems from the nanoscale to the geophysical scale and plays a crucial role.The microscopic mechanism of friction and the origin of the dynamic ordering in interacting particle systems are still controversial.Using Langevin simulations,we study the friction of two-dimensional colloids on the substrate with randomly distributed point-like pinning centers.We consider three different model colloidal systems,and in each system the colloidal particles interact with each other through repulsive interactions that have two different force ranges.We find two maximum static friction forces(the first maximum static friction f_(c1)^(d) and the second maximum static friction f_(c2)^(d)).The interference between short-range repulsive interactions with similar force ranges in model-3 colloidal system can lead the repulsion between particles near pinning centers to significantly increase,resulting in a decrease in f_(c1)^(d) and an enhanced orderly movement along the direction of external driving forces above f_(c2)^(d).The results provide guidance for revealing the friction mechanism in the colloidal particles with interactions that have different force ranges.