High-σ and Low-σ Polyacetylene: A Comparison

Abstract

Different films of iodine-doped Naarmann polyacetylene prepared under similar conditions differ by up to a factor of 30 in their conductivities parallel to the stretching direction, ^σ∣∣, while only minor differences in conductivity are found for different parts of the same film. Thinner films exhibit systematically higher values of ^σ∣∣ (up to 104 000 S/cm) than thicker films. While no difference in the typical temperature dependence is found between high-σ and low-σ samples, three systematic differences are observed which are related to the stretching process. High-σ samples show a larger increase in conductivity due to mechanical stretching, the conductivity anisotropy reaches higher values and the fibrillar interior of the samples is more homogeneously oriented. However, the results indicate that differences in the degree of fibrillar orientation can explain only part of the differences in conductivity between different samples.