One-pot facile simultaneous synthesis of conductive Ag-polyaniline composites using Keggin and Preyssler-type phosphotungstates.

Two heteropolytungstate structures, Keggin (HPWO) and Preyssler (H[NaPWO]), were used to synthesize conductive silver nanoparticle-polyaniline-heteropolytungstate (AgNPs-PAni-HPW) nanocomposites. During the oxidative polymerization of aniline, heteropolyblue was generated and served as the reducing agent to stabilize and distribute AgNPs within "PAni-Keggin" and "PAni-Preyssler" matrixes as well as on their surfaces. The prepared nanocomposites and AgNPs were characterized using UV-visible (UV-Vis) and Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), pore size distribution BET, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). UV-Vis results showed different stages of the formation of metal NPs embedded in the polymer-HPW composites, and FT-IR spectra presented characteristic bands of PAni, Keggin and Preyssler anions in the composites confirming no changes in their structures. The presence of AgNPs and an intensely crystalline matrix were confirmed by the XRD pattern. The BET surface areas were found to be 38.426 m g for "AgNPs-PAni-Keggin" and 29.977 m g for "AgNPs-PAni-Preyssler" nanocomposites with broad distributions of meso-porous structure for both nanocomposites. TEM and SEM images confirmed that the type of heteropolyacids affected the size of AgNPs. This is the first report that uses Keggin and Preyssler-type heteropolytungstate to synthesize "AgNPs-PAni-HPW" nanocomposites in an ambient condition through a low-cost, facile, one-pot, environmentally friendly and simultaneous oxidative polymerization protocol.