Coaxially Aligned Polyaniline Nanofibers Doped with 3-Thiopheneacetic Acid through Interfacial Polymerization

Abstract

Coaxially aligned polyaniline (PANI) nanofibers doped with 3-thiopheneacetic acid (TAA) were chemically synthesized by the interfacial polymerization of aniline in the presence of TAA, using iron (III) chloride hexahydrate (FeCl3·6H2O) as the oxidant. The morphology, crystallinity, room temperature conductivity, and coaxial alignment of the PANI-TAA nanofibers were highly dependent on the organic solvent used for the interfacial polymerization, the oxidant, and also the molar ratio of the aniline to TAA. Hexane, diethyl ether, dichloromethane, chloroform, and acetone were used as the organic solvents, and chloroform proved to be the best solvent for the formation of PANI-TAA nanofibers. The redox potential of the oxidant is the key to controlling the morphology and diameter of the PANI-TAA nanofibers. The use of FeCl3as the oxidant leads to the formation of thin (∼50 nm) PANI-TAA nanofibers, which increased in length, crystallinity, conductivity, and coaxial alignment as the molar ratio of TAA to aniline was increased from 0.1 : 1 to 1 : 1. By comparison, only granular PANI was obtained when ammonium persulfate (APS), which has a higher redox potential, was used as the oxidant. The doping function of TAA in the PANI-TAA nanofibers was confirmed by means of FTIR and UV-Visible spectroscopy.