Enhanced Electric Polarization and Polar Switching of Dipolar Aromatic Liquids Confined in Supramolecular Gel Networks

Dipolar aromatic liquids confined in the interstitial domains of chiral organogels show significantly enhanced electric polarization, as compared with those of pure liquids alone or organogels formed with nonpolar liquids. Intriguingly, nitrobenzene gels showed a supramolecular polar switching phenomenon; i.e., hysteresis in the polarization (P)-electric field (E) curves was observed for the gel above the melting point of the solvent. This indicates that the nitrobenzene molecules confined in the chiral nanofibrous gel networks exert macroscopic polarization whose direction is inversed depending on the direction of the external electric field. The anomalously enhanced electric polarization and polar switching phenomenon of supramolecular gels in varied solvents are scrutinized by the positive-up-negative-down (PUND) measurements, and the interactions between the gel nanofibers and the polar solvent molecules play crucial roles for the emergence of the polar switching phenomenon. This work presents for the first time that dipolar liquid molecules filling the interstitial space of supramolecular gels exhibit a significant confinement effect. It provides a new perspective to design electric-field-responsive soft materials based on the functional liquid domains confined in their porous networks.