Morphology of Anion-Conducting Ionenes Investigated by X-ray Scattering and Simulation

J Phys Chem B. 2018 Feb 8;122(5):1730-1737. doi: 10.1021/acs.jpcb.7b10177. Epub 2018 Jan 24.

Abstract

We have studied the morphology of a novel series of benzimidazole-based ionenes, methylated poly(hexamethyl-p-terphenylbenzimidazolium) (HMT-PMBI), in halide form. Materials with anion-exchange capacities ranging from 0 to 2.5 mequiv/g were studied. X-ray scattering reveals three length scales in the materials: ion-polymer spacing (4 Å), polymer-polymer interchain spacing (6 Å), and an intrachain repeat distance (20 Å). No long-range structure is apparent above the monomer length, which is rare in ion-conducting polymer membranes. In preliminary molecular dynamics simulations, water molecules were observed forming chains between ions, even at a modest level of hydration, providing an interpenetrating network where conductivity can occur.

Publication types

  • Research Support, Non-U.S. Gov't