Title

DIELECTRIC-RELAXATION STUDIES OF ACID-CONTAINING SHORT-SIDE-CHAIN PERFLUOROSULFONATE IONOMER MEMBRANES

Document Type

Article

Publication Date

4-27-1992

Department

Polymers and High Performance Materials

Abstract

The storage and loss components of the complex dielectric permittivities of aqueous H2SO4-containing short-side-chain perfluorosulfonic acid membranes were determined as a function of acid concentration and temperature. An equivalent circuit model and its mathematical representation is proposed for these ionomers. This simple, but successful, permittivity model reinforces our usual partitioning of the dielectric relaxation spectra into contributions that represent the short-range (intracluster) and long-range (intercluster) motions of ions throughout the known microphase-separated morphology. A low-frequency graphical feature on the experimental spectra that is reflective of and quantifies the tortuosity of long-range ion conductive pathways was identified and determined as a function of acid concentration and temperature. A high-frequency relaxation peak attributed to a fluctuating polarization that occurs at the cluster/TFE interfaces yields the time scales for intracluster ion motions and suggests the existence of two types of clusters for the case of low acid concentration.

Publication Title

MACROMOLECULES

Volume

25

Issue

9

First Page

2369

Last Page

2380