Charge Storage Mechanisms in Redox-Active Polymer Brushes

Electroconductive polymer brushes grafted to conductive electrodes are investigated as model electrodes for aqueous supercapacitors using the Scheutjens-Fleer self-consistent field (SF-SCF) framework. The model self-consistently resolves polymer conformations, ion partitioning, and redox-mediated electron hopping under applied potentials (0-0.7 V). We show that solvent quality and grafting density govern brush swelling and counterion uptake, thus shaping the charge-potential response. In a good solvent, brushes provide volumetric charge storage throughout a swollen layer, while in a poor solvent, charging drives a collapsed-to-swollen transition that produces sharp capacitance peaks. During this transition, the differential capacitance reaches 15-30 F/m², an order of magnitude higher than the bare-electrode baseline. These results demonstrate how redox-active electroconductive brushes integrate electric double-layer and pseudocapacitive mechanisms, providing design principles for polymer-brush-modified electrodes in both supercapacitors and ion-selective membranes.