Characterization of polyaniline/single-walled carbon nanotube composite films prepared by plasma polymerization

Abstract

Polyaniline (PANI)/single-walled carbon nanotube (SWCNT) composite films with good uniformity were prepared by in situ plasma polymerization of aniline containing SWCNTs. A unique method was used to inject the monomer and SWCNTs simultaneously into the plasma reactor. Chemically pre-functionalized SWCNTs-COOH and pristine SWCNTs were used in this study. Both types of the SWCNTs were plasma functionalized during their path to the substrate through the microwave plasma, which led to a uniform dispersion within the PANI matrix. The structure and morphology of the films were characterized by the Fourier transform infrared, X-ray diffraction, atomic force microscopy, and scanning electron microscopy. The Fourier transform infrared method confirmed the chemical bonding and the formation of the nanocomposite. While the X-ray diffraction results indicated that the composite has a relatively high ordered crystalline structure, which is expected to reveal high electrical conductivity. The atomic force microscopy micrographs specified a uniform distribution of the SWCNTs in PANI matrix with no aggregations and low roughness average, whereas the scanning electron microscopy micrographs revealed that SWCNTs of both kinds were completely coated by PANI and well dispersed in a continuous polymer matrix forming a conductive network. Films conductivity was examined by the Hall effect; the PANI/SWCNT composite showed a conductivity of 25 S/cm with using pristine SWCNTs of 1.5 wt% and 50 S/cm for composite using chemically pre functionalized SWCNTs-COOH of the same loading percentage, compared to that of pure PANI of 10−8 S/cm. It is concluded that the improved conductivity of the PANI/SWCNT composite films is due to the strong interaction between SWNTs and PANI, which simplifies the effective degree of electron delocalization.