Synthesis and characterization of HCl doped polyaniline grafted multi-walled carbon nanotubes core-shell nano-composite

Multi-walled carbon nanotubes (MWNTs) was modified with p-phenylenediamine (p-PDA) and hydrochloric acid (HCl) doped polyaniline (PANI) grafted MWNTs nano-composite was synthesized by in situ oxidation polymerization. Raman spectra, XPS, TEM and XRD reveal that modification does not decrease the integrity of outer graphite sheets in p-PDA modified MWNTs (p-MWNTs) excessively and results in phenylamine groups with concentration of 3.7% covalently grafted on the surface of p-MWNTs via amide bond. Oxidized phenylamine groups initiate polymerization and contribute to the formation of inner layer of PANI coatings. As self-assembly templates, p-MWNTs are encapsulated by PANI forming a homogeneous core (p-MWNTs)-shell (HCl doped PANI) nano-structure with controlled organization. In earlier reaction period, polymer chains are highly ordered and microcrystalline domains are enriched in the inner PANI layers. When deposition of PANI chains under less restriction, more amorphous parts are distributed in the outer layers of PANI coatings. TGA and conductivity data reveal that although chemical modification affects the performance of p-MWNTs, thermal stability and electronic conductivity at room temperature of HCl doped PANI grafted MWNTs nano-composite are highly improved owing to incorporation of p-MWNTs and covalent bindings between PANI and carbon nanotubes.