Multi-faceted role of blended poly(vinyl pyrrolidone) leading to remarkable improvement in characteristics of polyaniline emeraldine salt

A detailed study has been carried out to ascertain the specific interaction of poly(vinyl pyrrolidone) (PVP) with polyaniline emeraldine salt (PANT) in their blend (PANI-PVP blend of 2:1 molar ratio) prepared by in situ chemical oxidative polymerization of aniline with PVp. Incorporation of PVP is found to improve many of the characteristics of PANT, in particular, conductivity and its retention for a considerable period, thermal stability upto 150degreesC and steric arrangement and its retention. When PVP + I-2 complex is blended instead of PVP, the advantageous effects of PVP are reduced in proportion to the iodine content. This observation, together with the results of investigation of these blends by various instrumental techniques, reveals that PVP with its dipolar imide group carrying a fractional negative charge on carbonyl oxygen, could act as a polymeric functionalized co-dopant. Iodine complexation by charge transfer from this negative end, inhibits PVP's coulombic interaction with PANI and becomes responsible for the declining effect. Evidently, it is realizable that PVP plays a multi-faceted role involving the functions of co-doping, polymer support, structural enhancement, steric and thermal stabilization and solubilization, towards PANT. (C) 2004 Elsevier B.V. All rights reserved.