Synthesis and characterization of processable polyaniline doped with novel dopant NaSIPA

Aniline has been polymerized in the presence of a novel dopant sodio-5-sulfo-isophthallic acid (NaSIPA), via the chemical oxidative polymerization route. The thermal stability and processability of polyaniline prepared by indirect method (PD1) have been improved significantly (290°C) as compared to polyaniline doped with conventional inorganic dopants like HCl or H₂SO₄, without much loss of electronic conductivity (5.07 S/cm in PD1). This suggests its use for melt blending with engineering thermoplastics. However, polyaniline prepared by direct method (PD2) can be melt-blended only with conventional thermoplastics like polyethylene, polypropylene, polystyrene, etc. Low-temperature studies reveal the 1-D variable range hopping as a conduction mechanism for direct polymer (PD2), with parameters To and σo as 4112 K and 15.1 S/cm, respectively. However, for indirectly doped polymer (PD1) Arrhenius-type model, having parameters |(EF - EC)| and σC as 0.04 eV and 28.4 S/cm, respectively, it suited well. The coherence length as found from XRD data was around 28.8 nm for PD1 and 25.2 nm for PD2.