Preparation and characterization of soluble and DBSA doped polyaniline grafted multi-walled carbon nanotubes nano-composite

Abstract

Soluble and highly doped polyaniline (PANI) grafted multi-walled carbon nanotubes (MWNTs) nano-composite was synthesized by in situ oxidation polymerization, de-doping with ammonium hydroxide and doping the PANI-Emeraldine base (PANI-EB) grafted MWNTs nano-composite in N-methyl-2-pyrrolidinone (NMP) with Dodecyl benzene sulfonic acid (DBSA). Transmission electron microscope (TEM), Raman spectra, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and standard four-probe methods were employed to characterize morphology, chemical structure and electronic conductivity of the nano-composite. The results show that oxidized phenylamine groups of phenylamine groups contained MWNTs (p-MWNTs) initiate PANI polymerization on the surface of p-MWNTs. PANI coatings graft on the surface of p-MWNTs via amide bond forming homogeneous core (p-MWNTs)–shell (PANI) nano-structures. After doping PANI-EB grafted MWNTs nano-composite with DBSA, the attachment of soluble DBSA doped PANI chains on the surface of p-MWNTs via covalent bonding renders p-MWNTs compatible with polymer matrix and lead to DBSA doped PANI grafted MWNTs nano-composite soluble and stable in NMP. Owing to incorporation of p-MWNTs and chemical bridges between p-MWNTs and PANI chains, conductivity of DBSA doped PANI grafted MWNTs nano-composite at room temperature is increased by about two orders of magnitude over neat DBSA doped PANI.