Publications

Dielectric and Viscoelastic Response of Imidazolium Polymerized Ionic Liquids
with Different Counterions and Side Chain Lengths

A molecular-level understanding of dynamics in imidazolium-based ionomers with different counterions (Tf2N- and BF4-) and side chain lengths was investigated using X-ray scattering, oscillatory shear, and dielectric relaxation spectroscopy. Variations of the counterion size and side chain length lead to changes in glass transition temperature (Tg), extent of ionic aggregation, and dielectric constant, with consequences for ion transport. Imidazolium-based ionomers with larger counterion and longer side chain have lower Tg, resulting in higher ionic conductivity and mobility. Larger counterions or longer side chains also diminish ionic aggregation, and their ionomers have higher dielectric constants. Smaller counterions or shorter side chains promote ionic aggregation, and their ionomers have lower dielectric constants, which are directly reflected in the lower content of simultaneously conducting ions.

 

U. H. Choi, Y. Ye, D. Salas de la Cruz, W. Liu, K. I. Winey, Y. A. Elabd, J. Runt, R. H. Colby, Macromolecules,  47 (2), 777-790, 2014.
“Dielectric and viscoelastic responses of imidazolium-based ionomers with different counterions and side chain lengths”