Directed Ionic Transport and Polarizability in Poly(Ionic Liquid)-Grafted Nanoparticles

In our recent findings, we demonstrated that ionic liquid (IL) can become polarized under electric fields when mixed with poly(methyl methacrylate) (PMMA) at high concentrations. The polarizability of ions in this mixture consequently leads to the conductivity enhancement. We recently showed that the PIL-grafted nanoparticles (PILgNPs) form strings in solution and percolated nanostructures at micron lengths in films. This underlying nanostructure helps us to explain the highest conductivity achieved by the cooperative ion motion between polycation grafts. To investigate both the polarizability of IL with PMMA chains, and the ladder-like ion-hopping mechanism of PIL chains, we synthesized the PIL-b-PMMA copolymer-grafted nanoparticles. Our results indicate that the new copolymer hybrid design achieves significantly higher molar conductivity than PILgNPs. Moreover, as the length of PIL block increases, the conductivity improves accordingly. The well-dispersed nanoparticles with long PIL block suggest that particle percolation is not needed, and the corona connectivity between the particles can enhance the ionic pathways. The electric field application to the prepared samples indicates the polarizability of PIL chains is restricted with the incorporation of the PMMA block as measured in broadband dielectric spectroscopy. In the next phase, we will explore the effect of IL inclusion in the ion transport properties of PIL-b-PMMA copolymer-grafted NPs.