Effect of supercritical carbon dioxide treatment on the polarons of HCl-doped polyaniline films

In situ HCl‐doped polyaniline films were synthesized on glass substrates via chemical oxidative polymerization of aniline using ammonium peroxydisulfate as oxidant. The films were treated with supercritical carbon dioxide (SC‐CO2) at 30 MPa and 40 °C for 30 minutes. The physico‐chemical and electrical properties of the films were determined to establish the effect of supercritical carbon dioxide treatment on the polaron structures of polyaniline films. The treatment removed limited number of polarons which affected the properties of polyaniline. The treated films remained conducting despite that the conductance decreased substantially. The treatment enhanced the quinoid character of the films and altered the HOMO‐LUMO transitions. In addition, SC‐CO2 treatment was unable to remove the PANI precipitations adhering on the surface of the films. A mechanism on the effect of SC‐CO2 interaction to HCl‐doped PANI films was proposed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)