Synthesis and characterization of polyaniline-multiwalled carbon nanotube nanocomposites in the presense of sodium dodecyl sulfate

Polyaniline-carboxylic acid functionalized multi-walled carbon nanotube (PAni/c-MWNT) nanocomposites were prepared in sodium dodecyl sulfate (SDS) emulsion. First, the c-MWNTs were dispersed in SDS emulsion then the aniline was polymerized by the addition of ammonium persulfate in the absence of any added acid. SDS forms the functionalized counterion in the resulting nanocomposites. The content of c-MWNTs in the nanocomposites varied from 0 to 20 wt%. A uniform coating of PAni was observed on the c-MWNTs by field-emission scanning electron microscopy (FESEM). The PAni/c-MWNT nanocomposites have been characterized by different spectroscopic methods such as UV-Visible, FT-Raman, and FT-IR. The UV-Visible spectra of the PAni/c-MWNT nanocomposites exhibited an additional band at around 460 nm, which implies the induced doping of the MWNTs by the carboxyl group. The FT-IR spectra of the PAni/c-MWNT nanocomposites showed an inverse intensity ratio of the bands at 1562 and 1480cm^-1 as compared to that of pure PAni, which reveals that the PAni in the nanocomposites is richer in quinoid units than the pure PAni. The increase in the thermal stability of conductivity of the nanocomposites was due to the network structure of nanotubes and the charge transfer between the quinoid rings of the PAni and the c-MWNTs.