Conductivity measurements of novel, oriented polyaniline films

A novel combination of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and dichloroacetic acid (DCA) solvent has been used for processing polyaniline (PANi) into free-standing solvent cast films. At 60 % protonation of the nitrogen sites in PANi, the temperature dependent electrical conductivity, on warming from 15 to 300 K, is found to increase at first then decrease above 90 K. A second transition is seen at ~ 250 K where the rate of conductivity decrease is even greater. This second transition correlates well with an endothermic transition observed using differential scanning calorimetry (DSC). Stretch alignment of the films increases the conductivity along the stretch direction and raises the conductivity ‘turnover’ point to higher temperatures. However, the second transition is not significantly affected by orientation.