Tuning the Ionic Conductivity of Polymerized Ionic Liquid Homo-, Random, and Block Copolymers

摘要

Polymerized ionic liquids (PILs) are an emerging class of ion-conducting polymers based on the familiar chemistries of ionic liquids. In contrast to ionic liquids, either the cation or anion is tethered to the polymer backbone in a PIL which minimizes leakage of the charged species into neighboring materials (for example in a thin film transistor). A major advantage of PILs over conventional ion conducting membranes is that they can operate in the absence of water allowing for high temperature operation. In this project, we seek a better understanding of the conductivity mechanisms in PILs, particularly in materials which conduct protons. One of the main structural features of ion-conducting polymers is the aggregation of ionic groups due to the non-polar, low dielectric constant polymer backbone. These aggregates have a pronounced influence on the conductivity, viscosity, and dielectric constant of the material and we seek to tune these properties via two distinct routes. The first is through the incorporation of polar, non-ionic groups into the backbone of a random copolymer PIL. The second is via nanostructuring of PILs within self-assembled block copolymers containing a non-conductive, mechanically robust block.