SOLUTION-STATE NMR-STUDIES OF POLYANILINE STRUCTURE

We present the results of solution state NMR investigations of the structure of polyaniline in various oxidation states. The resolution obtained is much higher than that available from solid state techniques. We confirm that the majority of the material present in samples of leucoemeraldine base and emeraldine base have the previously postulated structures, but find that defects in the postulated structures may be present at concentrations up to 5 mole% of the repeat units. The nature of the defects cannot be identified with certainty, but some postulated defect structures can be excluded on the basis of chemical shift calculations. End groups form part of the ''defect'' resonances, but do not account for all of them. We believe that the considerable spectral complexity apparent in both the C-13 and N-15 spectra of emeraldine base reflect the large number of discrete conformational states of the polymer chain.