EAPSI: Elucidating the Role of Ionic Aggregate Structure on Polymer Dynamics for Charge Transport Applications

Middleton Luri R, Phildelphia PA

Investigators

Abstract

Global and US energy consumption increases every year and consequently substantial research efforts have been devoted to improving next-generation energy solutions to keep up with demand and improve efficiency. Currently, there is intense interest in acid-containing and ion-containing polymers as this class of polymers could enable the next generation of batteries, thin film capacitors, and proton exchange membranes in fuel cells. The goal of this project is to gain fundamental understanding of the coupling between ion motion and polymer dynamics in a model ion-containing polymer system. To optimize the ion transport kinetics, a performance bottleneck in these critically important to applications, one must understand the nature of this coupling. The specific expertise in the physics of complex liquids and instrumental capabilities of Dr. Ryusuke Nozaki?s lab at Hokkaido University in Japan will be essential to investigate dynamics in this class of polymers. Interest in ionomers and other polymers with acid, ionic and polar groups is fueled by these polymers? ability to selectively transport charged species. Dielectric relaxation spectroscopy (DRS) will be used to investigate the various relaxations in a series of homologous acid copolymers neutralized with metal salts such as lithium. DRS will measure relaxations on the timescales of ion conduction and polymer motion. This technique will be combined with a recently synthesized category of acid copolymers with high levels of molecular control during synthesis to probe the coupling of motion between polymer and ion. These precise copolymers and ionomers provide unprecedented molecular control that produces well-defined morphologies and thereby facilitate the improved understanding of structure-property relationships. Specifically, the differences between discrete and percolated ionic aggregate morphologies will be investigated with the goal of accelerating ion motion relative to polymer dynamics. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.