EPR and electrical conductivity in microporous polyaniline

Abstract We have studied a series of microporous polyaniline (PANI) samples, each of the structure with micro-channels and micro-caves inside (a diameter of 1.5–2.5 μm), formed as a non-periodic network of microrods. Microporous polyaniline is a paramagnetic material and strong EPR signals with the g -factor in the range of 2.0030–2.0032 and the line width Δ B between 1.80 and 6.50 Gs have been measured for samples of various electrical conductivity. The EPR line asymmetry is high (almost 1.5) in the case of PANI samples of the highest electrical conductivity (0.35 S/cm). We found that lithium cations present in the reaction medium can stabilise values of the EPR line asymmetry parameter and g -factor observed for PANI samples prepared in such conditions. Lithium cations are able to influence the intermolecular hydrogen bonding which is essential for the interchain coupling leading to an increase in the EPR line asymmetry and a higher electrical conductivity. Thus, the properties of PANI samples are modified by lithium cations.