Extreme strain localization and sliding friction in physically associating polymer gels.

Model physically associating gels deformed in shear over a wide range of reduced rates displayed evidence of strain localization. The nonlinear stress responses and inhomogeneous velocity profiles observed during shear rheometry coupled with particle tracking velocimetry were associated with the occurrence of rate-dependent banding and fracture-like responses in the gel. Scaling law analysis from traditional sliding friction studies suggests that, at the molecular level, deformation is confined to a shear zone with thickness comparable to the mesh size of the gel, the smallest structurally relevant length scale in the gel.