Exploring hydrogel tribology through mesoscale modeling

Biological hydrogels exhibit remarkably low friction at sliding interfaces, such as articular cartilage and the ocular surface. We develop a mesoscale model of polymeric hydrogels to probe their friction behavior. The hydrogel is represented as a random bead-spring network sliding against either a solid surface or another hydrogel, immersed in an explicit viscous solvent to account for hydrodynamic interactions. We examine hydrogel friction under varying normal loads and sliding velocities. We also probe the effects of solvents quality of friction behavior. We show that friction is characterized by the Weissenberg number and that its magnitude decreases with increasing load. To gain insights into gel friction, we examine the changes in hydrogel structure and density distribution with load and sliding velocity. The results of our study provide new insights into the micromechanics of hydrogel friction and can be useful for designing new hydrogels for tribological and biomedical applications.