Polyacrylonitrile-polyaniline composite nanofiber webs: Effects of solvents, redoping process and dispersion technique

Abstract

This study was carried out to examine the effect of different solvents (DMSO, NMP, DMF) and solvent mixtures, application of dispersion and mixing techniques during solution preparation and redoping process on polyacrylonitrile (PAN) and camphorsulfonic acid (CSA) doped polyaniline (PANI) composite nanofibers. It was observed that nanofibers produced from DMSO and NMP solvents had larger fiber diameters than nanofibers produced from DMF. When the crystallinity of the 100 % PAN nanofibers were compared, the nanofibers electrospun from DMSO had the lowest crystallinity values. The tensile breaking stress values of the nanowebs produced from DMSO and NMP were higher than nanowebs produced from DMF while the breaking elongation values of the nanowebs produced from DMF was higher. Mechanical dispersion technique resulted in higher tensile breaking stress values than corresponding magnetic stirring. The redoping process also affected the tensile properties of the nanowebs by increasing the breaking stress values and decreasing the breaking elongation values. When DMSO was used as a solvent for the production of composite nanofibers, the electrical conductivity values at around 10−6 S/cm were obtained corresponding to the semiconductive material range. The use of solvent mixtures resulted in better conductivity values than their counterparts. When CSA-NMP and CSA-NMP/DMF were compared, the nanofibers produced from the solvent mixture had higher conductivity values. On redoping, the conductivity increased 10 times and reached 1.2×10−5 S/cm. The reference samples with DMSO had the lowest cyclization temperature and enthalpy. Addition of PANI increased the thermal stability of the composite nanofibers in comparison with pure PAN.