Molecular Design and Characterization of Ionic Monomers with Varying Ion Pair Interaction Energies

Ionic liquid monomers with ion pair interaction energies ranging from 73.0 to 101.4 kcal/mol were designed by using the calculated electrostatic potential (ESP) values of the component ions. The ionic liquid monomers were classified as cationic monomers with an anionic counterion and anionic monomers with a cationic counterion. We evaluated the calculated ion pair interaction energy using counterion mobility as an indicator. One component of the ion pair was fixed onto a dielectric elastomer by using alkoxysilane coupling agents, while the counterion remained free to move under the applied voltage. We then measured the relative dielectric constant at 0.01 Hz, which is an indicator of the mobility of the counterion. The results showed a good correlation between the calculated ion pair interaction energy and the relative dielectric constant. The lower the ion pair interaction energy is, the easier the dissociation of the ion pair. From this result, we were able to prove the correlation between the calculate...