Confinement Effects in Dynamics of Ionic Liquids with Polymer‐Grafted Nanoparticles

Abstract

Ionic liquid mixed with poly(methyl methacrylate)-grafted Fe 3 O 4 nanoparticle aggregates at low particle concentrations was found to exhibit different dynamics and ionic conductivity than that of pure ionic liquid in our previous studies. In this work, we report on the quasi-elastic neutron scattering results of ionic liquid containing polymer-grafted Fe 3 O 4 nanoparticles at higher particle concentrations. The diffusivity of imidazolium (HMIM + ) cations of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HMIM-TFSI) in the presence of poly(methyl methacrylate)-grafted Fe 3 O 4 nanoparticles is discussed through the confinement. Analysis of the elastic incoherent structure factor revealed that the confinement radius decreased with the addition of grafted particles in HMIM-TFSI/solvent mixture. We propose the confinement that is induced by the high concentration of grafted particles shrinks the HMIM-TFSI restricted volume. We further conjecture that this enhanced diffusivity occurs as a result of the local ordering of cations within aggregates of poly(methyl methacrylate)-grafted Fe 3 O 4 nanoparticles.

Enhanced Ion Conductivity in a Poly(ionic liquid)-Grafted Nanoparticle-Based Single-Ion Conductor

“…In conventional electrolyte systems, the diffusivity differences of anions and cations lead to concentration gradients of ion carriers, limiting the performance of lithium-ion batteries. Single-ion conducting polymer electrolytes are highly promising conducting systems for energy applications. , The mobility of polymer backbone, glass transition temperature, and ion size impact the decoupling of ionic conductivity from segmental dynamics. − In addition, the ion solvation that is facilitated either by cosolvent addition or through preferential interactions between polymer chains and ions enhance the number of mobile (free) charge carriers. − In this study, the ion transport mechanism in ionic liquid (IL)-based polymer hybrids are investigated in solution and with the addition of IL. The underlying particle nanostructures and the polycation chain lengths are examined to explain the ion conductivity, which is unique for the single-ion conductor design.…”