Optimizing the charge transport in redox-active gels: a computational study.

Redox-active polymer gels are promising materials for various applications, such as energy conversion and storage systems, organic electronics, soft-robotics, sensors and others. This is in part due to the remarkable structural tunability of these materials. The gel may adopt different conformations depending on the crosslinking density, solvent temperature and other conditions. These parameters affect its behavior, including the dynamics of the charge transport between the redox groups grafted to the polymer subchains, which is of utmost importance for electrochemical applications. Here, we employed coarse-grained molecular dynamics simulation to investigate the impact of crosslinking, redox group content and solvent quality on both subchain mobility and charge transport speed. In particular, unexpected behavior of the system under the theta-solvent condition was found and analyzed. The obtained results provide useful guidelines to facilitate the best conditions for enhanced "redox induced" conductivity in polymer gels, which would help the development of redox-flow batteries and other electrochemical devices.