Synthesis and Characterization of Processable Multi-Walled Carbon Nanotubes—Sulfonated Polydiphenylamine Graft Copolymers

Water soluble and processable nanocomposites composed of multi-walled carbon nanotubes (MWNTs) and poly(diphenylamine sulfonic acid) (PDPASA) are synthesized and characterized. Two types of methodologies are adopted. MWNTs are covalently functionalized with 2,5-diaminobenzene sulfonic acid (DABSA) and further in situ polymerized with diphenylamine-4-sulfonic acid (DPASA). This results in the formation of nanocomposites, MWNT(DABSA)-g-PDPASA, in which PDPASA is presented as the graft chains onto MWNTs. In another approach, DPASA is in situ polymerized in presence of unfunctionalized MWNTs, results in a nanocomposite in which MWNTs are present as entrapped mass in PDPASA matrix. Both nanocomposites are found to be water soluble and can form free standing films. The conductivity of MWNT(DABSA)-g-PDPASA and MWNT/PDPASA is found to be 1.25 mS · cm⁻¹ and 0.65 mS · cm⁻¹, respectively, which is higher than that of pristine PDPASA (0.25 × 10⁻⁵ S · cm⁻¹). The nanocomposites are characterized for their structure, morphology, optical and thermal properties.