?STUDY OF PARAMAGNETISM IN PYRROLE BASED CONDUCTING POLYMERS USING ESR MEASUREMENTS AT Low TEMPERATURES AND PRESSURES
Keywords:
Key words: Paramagnetic defects, Radical cation, Spin concentration, Deuterated and protonated polypyrrole, Polarons and bipolarons.Abstract
A series of ESR experiments were carried out at atmospheric as well as low pressures in order to find any relation-
ship between paramagnetic species and the charge carriers in pyrrole based electrically conducting polymers. ESR
spectra recorded for a range of polymer sampleshavingelectrical conductivities spreadover four orders of magnitude
suggest that apparently there is no link between the paramagnetic centres and bipolarons which serve as the major
charge carriers in these materials. A series of ESR measurements at low temperatures for pyrrole based polymers
showthat mostofthepolymers obeyCurie-Weisslawintermsofincreaseinspinpopulations.Differenceinbehaviour
of various polymers in terms of changes in spin populations, line shape and line width is attributed to the difference
in molecular structure and morphology.
