Ionic diffusion in polymer matrices

Abstract

The mass transport of ionic doping species in conducting polymers is of crucial importance in determining the effectiveness of these materials in many of their applications. Recent experiments using a new gravimetric technique have provided values for the diffusion coefficients and migration activation energies of a number of dopants into polyacetylene. Analogous measurements of absorption, desorption and isotopic exchange into polymeric crown ethers suggest that these materials may have considerable potential as ion-exchange membranes. The conducting polymer systems have also recently been investigated using atomistic simulation techniques. These have predicted the most stable structures for the pristine polymer substrates and have been used to determine the optimum locations and to investigate diffusion pathways for the dopant species in their polymer hosts. The calculations suggest that the polymer chains adopt a corrugated rather than planar conformation in the perfect doped lattices and that potassium ions in polyacetylene should be highly mobile.