Structural effect of redox active sites on electron hopping rate in mixed conducting copolymers

Abstract

AbstractThe copolymers consisting of a redox monomer, vinylferrocene or 10‐methyl‐3‐vinylphenothiazine, and an ion‐conducting monomer, ω‐methoxy‐nona(ethylene oxide)‐methacrylate, have been prepared. The copolymers, complexed with lithium perchlorate, exhibit reversible redox activity in the absence of low molecular solvents. The charge transport during the redox reactions is carried out by electron hopping reactions between the redox active centers, indicating that the copolymers can be regarded as intrinsic ion/electron mixed conductors. The electron hopping rates during the redox reactions have been evaluated by using an electrochemical technique under diffusion‐controlled conditions. The electron diffusion coefficients in the vinylferrocene and 10‐methyl‐3‐vinylphenothiazine copolymers are 6.8 × 10−12 cm2 sec−1 and 3.2 × 10−11 cm2 sec−1 at room temperature, respectively, and are larger in the latter copolymer. The electron hopping rate would be influenced by the slow and temperature‐dependent dynamics of the polymer segment, judging from the relatively low electron diffusivity and from its quite large and non‐Arrhenius temperature dependency.