Multiwalled carbon nanotube/polyaniline thermoreversible gel composites

Composites of multiwalled carbon nanotubes (MWCNTs) in a dinonylnaphthalene disulphonic acid (DNNDSA)-doped polyaniline (PANI) thermoreversible gel were prepared from a formic acid medium. A three-dimensional fibrillar network and a reversible first order phase transition characterize the systems as thermoreversible gels. Transmission electron micrographs indicate that the MWCNTs are well dispersed in the gel and PANI-DNNDSA wraps the MWCNT surface unevenly. pi-pi, CH-pi and acid-base interactions are evident from Fourier transform infrared spectroscopy. Thermal stability increases with increasing MWCNT content and the storage modulus of the composites increases dramatically. Photoluminescence increases significantly in the composites showing a red shift of the emission peak with increasing MWCNT content. The pi band-polaron band transitions show a red shift and the dc conductivity increases two orders of magnitude over that of the PANI-DNNDSA gel with the addition of MWCNTs. The current-voltage characteristic curves are Ohmic in nature and the current increases appreciably with increasing MWCNT concentration. (C) 2009 Elsevier B.V. All rights reserved.