Figure 4

(a) EPR \(T_1\) relaxation time distributions for PTMA–CB (green) and PTMA–CB–electrolyte (blue) samples, compared to a TEMPO methacrylate–CB (weight ratio of 1:30) reference sample (brown dashed). Inversion recovery experiments were conducted at 30 K and \(T_{1}\) data were inverted using an exponential kernel to obtain the distributions. (b) Schematic representation of the distribution of monomer radicals (green dots) in the sample. Fast \(T_1\) relaxation of the isolated radicals in PTMA–CB imply a good, direct contact with CB (top), with possible participation in electron hopping pathways (black arrows). A uni-modal distribution exhibited by the PTMA–CB, similar to the 1:30 monomer–CB sample, indicates that the isolated radicals are isotropically distributed on the CB surface. In case of PTMA–CB–electrolyte (bottom), the isolated radicals dissolve in the electrolyte, losing contact with CB and, consequently, exhibiting a slower \(T_1\) relaxation.