Two years ago conductivity values nearly as high as copper were published for highly oriented polyacetylene, a prototype material for conducting polymers. The reasons for this elevated conductivity are still not clear. The objective of our proposal is to discover the mechanisms responsible for these high values, to connect them with other material properties and to improve systematically the quality of synthesis.
The HICOPOL consortium has in joint effort clarified the conditions under which a chemical synthesis for very highly conducting material can be carried out. More important, based on experiments and on theoretical work by the various partners and using the relevant information available in the published literature, the mechanism of the electrical conductivity has been elucidated and is now fairly well understood. The knowledge obtained from studying polyacetylene is of paramount importance to optimize those conducting polymers which are actually in industrial use like polyaniline, polypyrrole and polythiophene. Moreover it will help to improve those conjugated polymers which will be used for organic light emitting devices. The expertise gained from the necessity to deal with the electrical conductivity of polymer chains, bundles and fibers will be used in future cooperative projects on the newly discovered carbon nanotubes and their assessment for technological uses. The experimental technique developed for conductivity measurements on a micrometer scale has merged into the new activity of molecular rectification and molecular electronics, which the members of the consortium are attacking now with great enthusiasm.
Only the combination of different specialized experimental methods on exactly the same type of samples allows the evaluation of these parameters and requires the collaboration of different groups. These proposed methods are optical spectroscopy and Raman investigations, DC- and AC- conductivity, transient photoconductivity and photoinduced absorption, nuclear magnetic resonance and electron spin resonance, electron energy loss spectroscopy, and structural investigations. The results obtained for polyacetylene should then, hopefully be transferred to other conducting polymers.