Sensing properties of sulfonated multi-walled carbon nanotube and graphene nanocomposites with polyaniline

Abstract

Here, we discuss one of the simplest approaches for chemical functionalization of in-situ prepared polyaniline (Pani) and its nanocomposites with multi-walled carbon nanotubes (MWCNT) and graphene (GN) in chlorosulphonic acid. The effect of polymerization and functionalization was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, Field emission scanning electron microscopy (FESEM) and electro-thermal analysis. Results also revealed the presence of π−π interactions between Pani and carbon allotropes leading to the formation of charge-transfer complexes. This strong π−π interaction significantly increased the resultant electrical conductivity, stabilizing them as well. Further, theirs back to back sulphonation in chlorosulphonic acid significantly enhanced the solubility in one way but caused a heavy loss in conductivity conversely. The thermoelectric properties of the as-prepared nanocomposites were investigated as a function of MWCNT and GN contents. It was observed that as-prepared Pani/GN nanocomposites showed a greater electrical conductivity as well as an improved thermal stability in terms of DC electrical conductivity retention under isothermal and cyclic ageing conditions compared with Pani/MWCNT and Pani. Finally these oxidative products were also studied for their sensing response towards amine to detect whether the particular compound is either 1°, 2°, or 3° amine. Keywords: In-situ polymerization, Pani/MWCNT and Pani/GN nanocomposite, Sulphonation, Isothermal and cyclic ageing technique, Amine identification