In situ ESR studies over wide temperature range for conducting polymers

In this work, in situ variable temperature electron spin resonance (ESR) measurements were realized for the first time to verify the spin nature of conducting polymers at controlled potentials. By using mixed solvents consisting of water and propanol in 1:1 volume ratio the temperature window was widened to 100 °C (−40 to +60 °C) for the study of polyaniline. According to the temperature dependence of ESR intensities obtained with this technique, it can be clearly seen that polyaniline in HCl solutions took on the Curie spin behavior at low doping level (0.0 V vs AgCl/Ag), and turned to the Pauli spin behavior at high doping level (0.4 V where conductivity reached about its maximum).