STUDIES ON SUBSTITUTED DERIVATIVES OF POLYANILINE

Aromatic ring and N-substituted derivatives of polyaniline have been p repared by peroxidisulphate oxidation of respective substituted anilin es under different polymerization conditions, such as, temperature, el ectrolyte composition and monomer to oxidant ratio.,The products forme d under different conditions exhibit significantly different conductiv ity, band width and exciton band transitions as well as crystalline ch aracteristics. The temperature dependence of conductivity, microwave a nd dielectric data and ESR studies lend support to the suggestion that in polyaniline the electrons are three dimensionally localized and co nsist of bundle of chains which form 'metallic' bundles. These are the crystalline regions of the polymer in which the electron wavefunction s are three dimensionally extended. The metallic bundles are separated by amorphous regions in which charge hopping dominates the macroscopi c conductivity. The coherence, most probable hopping distance, hopping energy and localization length have been compared for the series of p olymers. It is also concluded that interchain coupling and coherence a re suppressed due to substitution and the conduction electrons in the amorphous region may be localized to single chains. Thus, such polymer forms a class of 1-D disorder conductor.