Spectroscopic, structural and transport properties of conductive polyaniline processed from fluorinated alcohols

Studies of PANI protonation in fluorinated alcohols are presented. Three solvents have been tested, namely 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), 1,1,1,3,3,3-hexafluoro-2-phenyl-2-propanol (HFPP), and 1,1,1,3,3,3-hexafluoro-2-(p-tolyl)-propanol (HFTP). It has been demonstrated that the degree of the broadening of the NIR absorption, which can be considered as a measure of polaron delocalization, depends strongly on the selection of an appropriate protonating agent-solvent couple. Several couples, giving spectra similar to that reported for PANI(CSA)(0.5) in m-cresol, have been found. Processing of PANI from HFIP solutions leads to films with improved PANI chains stacking order as evidenced by X-ray diffraction studies. The films exhibit metallic type of conductivity down to 200 K. The temperature dependence of the conductivity over the whole temperature range studied has been fitted using a combination of a metallic and hopping contribution in the frame of a heterogeneous disorder picture of PANI.