SOLUTION-STATE NMR-STUDIES OF POLYANILINE STRUCTURE

We present the results of solution state NMR investigations of the str ucture of polyaniline in various oxidation states. The resolution obta ined is much higher than that available from solid state techniques. W e confirm that the majority of the material present in samples of leuc oemeraldine base and emeraldine base have the previously postulated st ructures, but find that defects in the postulated structures may be pr esent at concentrations up to 5 mole% of the repeat units. The nature of the defects cannot be identified with certainty, but some postulate d defect structures can be excluded on the basis of chemical shift cal culations. End groups form part of the ''defect'' resonances, but do n ot account for all of them. We believe that the considerable spectral complexity apparent in both the C-13 and N-15 spectra of emeraldine ba se reflect the large number of discrete conformational states of the p olymer chain.