Grafting of Polyaniline onto the Surface of 4-Aminobenzoyl- Functionalized Multiwalled Carbon Nanotube and Its Electrochemical Properties

Polyaniline (PANi)-grafted multiwalled carbon nanotube (MWNT) composite is prepared by a two-step reaction sequence. MWNT is first functionalized with 4-aminobenzoic acid in polyphosphoric acid/phosphorous pentoxide as a ‘‘direct’’ Friedel-Crafts acylation reaction medium. The resultant 4-aminobenzoyl-functionalized MWNT is then treated with aniline using ammonium persulfate/aqueous hydrochloric acid to promote a chemical oxidative polymerization, leading to PANi-grafted MWNT composite. The resultant composite is characterized by elemental analysis, Fourier-transform infrared spectroscopy, wide-angle X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, UV–vis absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and electrical conductivity measurement. The thermooxidative stability and electrical conductivity of PANi-grafted MWNT composite are improved compared to those of PANi. Specifically, the electrical conductivity of PANi-grafted MWNT is improved 10– 900 times depending upon the level of doping. The capacitance of the composite is also greatly enhanced. VC 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3103–3112, 2010