Abstract
The unique properties of ionic liquids (ILs) have made them promising candidates for electrochemical applications. Polymerization of the corresponding ILs results in a new class of materials called polymerized ionic liquids (PolyILs). Though PolyILs offer the possibility to combine the high conductivity of ILs and the high mechanical strength of polymers, their conductivities are typically much lower than that of the corresponding small molecule ILs. In the present work, seven PolyILs were synthesized having degrees of polymerization ranging from 1 to 333, corresponding to molecular weights (MW) from 482 to 160 400 g/mol. Depolarized dynamic light scattering, broadband dielectric spectroscopy, rheology, and differential scanning calorimetry were employed to systematically study the influence of MW on the mechanism of ionic transport and segmental dynamics in these materials. The modified Walden plot analysis reveals that the ion conductivity transforms from being closely coupled with structural relaxation to being strongly decoupled from it as MW increases.
| Original language | English |
|---|---|
| Pages (from-to) | 4557-4570 |
| Number of pages | 14 |
| Journal | Macromolecules |
| Volume | 49 |
| Issue number | 12 |
| DOIs | |
| State | Published - Jun 28 2016 |
Funding
The authors thank Dr. J. C. Johnson for helping with the synthesis of IL-1. The dn/dc measurements were conducted at the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory (ORNL). The authors thank Dr. H. M. Meyer III for performing the X-ray photoelectron spectroscopy measurements at High Temperature Materials Laboratory at ORNL. A.P.S. and J.M. acknowledge the financial support by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. F.F. and A.P.H. thank the NSF Polymer Program (DMR-1408811) for funding.