Electrically conductive hydrogel composites made of polyaniline nanoparticles and poly(N-vinyl-2-pyrrolidone)

A novel electrically conductive composite material, consisting of polyaniline (PANI) nanoparticles dispersed in a polyvinyl pyrrolidone (PVP)hydrogel, was prepared ‘in situ’ by water dispersion polymerisation (DP) of aniline using PVP as steric stabiliser, followed by g-irradiationinduced crosslinking of the PVP component. Conversion yield of aniline into PANI particles was determined via HPLC and gas chromatography,while structural confirmation of the synthesised polymer was sought by FTIR. Morphology and dimensions of PANI particles into the coloured,optically transparent hydrogel was determined by electronic microscopy; moreover, swelling behaviour of composite hydrogels in different buffersolutions was investigated by gravimetric measurements and compared to that of pure PVP hydrogels.Cyclic voltammetry experiments were carried out both on these hydrogels and on the parent aqueous dispersions, at different pH values of thesuspending/swelling medium, while conductivity of the composite hydrogels was derived from Impedance Spectroscopy; in both cases resultswere compared to those relative to hydrogels containing commercial-grade PANI particles.