Multimodal Operando Characterization of Layering and Wear at Concentrated Polymer Brush Interfaces

, exhibits a nonmonotonic dependence on applied load. This behavior is interpreted as a Raman-detectable signature of compression-induced molecular-state changes in the confined CPB layer, reflecting changes in molecular mobility and local structural heterogeneity. The transition from a highly swollen, relatively mobile state to a deswollen, more constrained molecular state was closely associated with the onset and acceleration of CPB wear. Layer-resolved wear analysis, achieved by alternately performing contact and friction tests, demonstrated that CPB wear proceeds via a random chain-scission mode, in which the dilute layer is continuously regenerated while the concentrated layer gradually diminishes. Multimodal operando measurements during sliding revealed that this random scission is associated with localized tensile-strain-like deformation imposed on polymer chains under frictional shear in the glassy-like confined state. These results establish a unified operando framework linking hierarchical layering, compression-induced molecular-state changes, and wear mechanisms at polymer brush interfaces and provide design principles for achieving durable, superlow-friction polymer brush lubrication systems.