Interactions between polyaniline and methanol vapour

UV-VIS spectroscopy, electron spin resonance spectroscopy CESR) and conduct ivity measurements have been used to characterise the interactions between methanol vapour and polyaniline. The data indicates that the methanol hydro gen bonds to two locations on the emeraldine base such that it is able to f orm a bridge between the polymer chains causing twisting. This prevents the few remaining polarons from moving beyond a few monomer units, effectively localising them, giving rise to a decrease in conductivity and an increase in absorption at ca. 1.6 eV. However, in the case of the emeraldine salt p rotonation of the quinoid moieties' nitrogen restricts the number of potent ial hydrogen bonding sites, preventing the methanol from forming a bridge b etween two polymer chains. At the same time, the high conductivity of the e meraldine salt allows the charge that is transfer to the polyaniline, as a result of the hydrogen bonding to the methanol, to be distributed along the conjugated chain in the form of polarons and bipolarons. (C) 2000 Elsevier Science B.V. All rights reserved.