Characterization of PTMA for Organic Radical Batteries Using Small Angle Neutron Scattering*

Stable radical polymers have become attractive as active layers in organic radical batteries. Specifically, (2,2,6,6-tetramethylpeperidinyloxy-4-yl methacrylate) (PTMA) is not a characteristic conductive material, however it exhibits extremely rapid electron charge kinetics, comparable to traditional transition metal ions. The feasibility of organic radical batteries is limited by the minimal knowledge of the correlation of functional efficiency and structural changes the polymer undergoes throughout the redox process during charging. Small angle neutron scattering is utilized to correlate structural changes of the PTMA polymer as the radical concentration is increased from 10% to fully saturated with radical moieties. These studies also investigate the structural changes and reorganization of the PTMA during the oxidation cycles. This analysis provides structural information on the flexibility of the polymer chains and the inter-chain interactions of radical groups between neighboring solvated chains. These studies provide integral insight that may be used to improve the performance of organic radical batteries by elucidating molecular structure-functional property relationships.