Computational study of Adhesion and Friction Behavior of Crosslinked Polymer Network

In this study, we have utilized a molecular dynamics simulation approach to understand adhesion and friction behaviour of crosslinked polymer networks. We have used breakable quartic bond to model crosslinked polymers. We explored the structural characteristics and evaluated the coefficient of friction (CoF) as a function of crosslinked monomer fraction (cross-linking bond density) in four-fold cross-linked polymer networks. To estimate CoF, a rigid indenter was inserted to different depths of indentation. Subsequently a constant sliding speed was applied while keeping the depths of indentation fixed. Normal and friction forces were calculated at each depth to estimate CoF through a linear curve-fitting. For adhesion studies, using the force vs. displacement curve we quantified adhesion through the forces during the separation of rigid indenter from surface of crosslinked polymeric materials while unloading after indentation into the sample. The results indicate that as the fraction of crosslinked monomers increases, the stiffness of the crosslinked network increases, while the force of adhesion and CoF decrease. Additionally, increasing the depth of indentation during friction leads to higher frictional forces.