Synthesis and Electrical Properties of Polyaniline/Polyaniline Grafted Multiwalled Carbon Nanotube Mixture via Suspension Polymerization

Abstract

The mixture of polyaniline (PANi) and PANi-grafted multiwalled carbon nanotube (PANi/PANi-g-MWNT mixture) was prepared by suspension polymerization. MWNT was first functionalizaed with 4-aminobenzoic acid via “direct” Firedel-Crafts acylation in polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5) medium to afford 4-aminobenzoyl-functionalized MWNT (AF-MWNT). The resulting 4-aminobenzoyl-functionalized multiwalled carbon nanotube was then treated with aniline in the presence of ammonium persulfate/aqueous hydrochloric acid to promote a suspension polymerization. The resultant composite was characterized by elemental analysis, Fourier-transform infrared spectroscopy, wide angle x-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis absorption spectroscopy, florescence spectroscopy, cyclic voltammetry, and electrical conductivity measurement. The electrical conductivity of polyaniline grafted multiwalled carbon nanotube composite was improved compared to that of polyaniline control. Specifically, the electrical conductivity of polyaniline grafted multiwalled carbon nanotube was improved 1.5~3500 times depending upon the level of doping of what. The capacitance of the composite was also greatly enhanced.