DIFFUSION OF IODINE IN POLYACETYLENE

The diffusion of iodine into polyacetylene has been studied as a function of temperature using a gravimetric method. The experimental data have been interpreted with a microscopic model involving diffusion into cylindrical fibrils. The interfibrillar diffusion coefficient for I3− in (CH)x. is ~ 10−17 cm2 · s−1 at room temperature (corresponding to an overall diffusion coefficient of ~ 10−9 cm2 · s−1). The measurement of this parameter in the temperature range −20° to +30°C has given an activation enthalpy of 0.2 eV. The influence of the concentration of the doping source has been investigated. A limited enhancement is observed on the D values but no influence on the activation enthalpy. The influence of the synthesis of the material has also been examined. The results are compared in polyacetylene prepared by the Shirakawa and the Naarmann methods, respectively. © 1990, The Electrochemical Society, Inc. All rights reserved.