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

Abstract

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 <inline-formula><tex-math id="M5">\begin{document}$ f_{{\text{c}}1}^{\text{d}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20231701_M5.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20231701_M5.png"/></alternatives></inline-formula> and the second maximum static friction <inline-formula><tex-math id="M6">\begin{document}$ f_{{\text{c2}}}^{\text{d}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20231701_M6.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20231701_M6.png"/></alternatives></inline-formula>). The interference between short-range repulsive interactions with similar force ranges in model-3 colloidal system can lead the repulsion between particles near pinning centers to significantly increase, resulting in a decrease in <inline-formula><tex-math id="M7">\begin{document}$ f_{{\text{c}}1}^{\text{d}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20231701_M7.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20231701_M7.png"/></alternatives></inline-formula> and an enhanced orderly movement along the direction of external driving forces above <inline-formula><tex-math id="M8">\begin{document}$ f_{{\text{c2}}}^{\text{d}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20231701_M8.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20231701_M8.png"/></alternatives></inline-formula>. The results provide guidance for revealing the friction mechanism in the colloidal particles with interactions that have different force ranges.