Investigating the complex interaction between polymer brush grafted surface in the approach-sliding using atomic modeling method

Polymer brush has already been widely used to modify the surface property while there is little research about the interaction between polymer-bearing surfaces at atomic scale. The complex multibody interaction among atoms makes it difficult to characterize the microscopic dynamic process using continuum mechanics. Molecular dynamics method has already been justified to be an efficient theoretical toolkit for investigating the complex dynamic behavior at atomic scale. Friction interface modified by polymer brush in confined space and the corresponding effect are investigated using parallel molecular dynamics simulation method. It is shown that some chains stretch along the direction of flow while others shrink inside the brush resulted by the normal compression. The normal force quickly increases when two end-grafted surfaces are brought into contact while the shear force keeps smaller under the same circumstances. The friction coefficient between polymer brush grafted surfaces is gradually decreased with the increasing of sliding speed which means polymer brush can dramatically improve working conditions. The components of the chains prefer to repel each other as much as possible and weaken interactions among them by stretching away and thus reducing the entropy of the chain.