PANI-WO 3 ·2H 2 O Nanocomposite: Phase Interaction and Evaluation of Electronic Properties by Combined Experimental Techniques and Ab-Initio Calculation.

The development of conjugated polymer-based nanocomposites by adding metallic particles into the polymerization medium allows the proposition of novel materials presenting improved electrical and optical properties. Polyaniline Emeraldine-salt form (ES-PANI) has been extensively studied due to its controllable electrical conductivity and oxidation states. On the other hand, tungsten oxide (WO 3 ) and its di-hydrated phases, such as WO 3 ·2H 2 O, have been reported as important materials in photocatalysis and sensors. Herein, the WO 3 ·2H 2 O phase was directly obtained during the in-situ polymerization of aniline hydrochloride from metallic tungsten (W), allowing the formation of hybrid nanocomposites based on its full oxidation into WO 3 ·2H 2 O. The developed ES-PANI-WO 3 ·2H 2 O nanocomposites were successfully characterized using experimental techniques combined with Density Functional Theory (DFT). The formation of WO 3 ·2H 2 O was clearly verified after two hours of synthesis (PW 2 nanocomposite), allowing the confirmation of purely physical interaction between matrix and reinforcement. As a result, increased electrical conductivity was verified in the PW 2 nanocomposite: the DFT calculations revealed a charge transfer from the p -orbitals of the polymeric phase to the d -orbitals of the oxide phase, resulting in higher conductivity when compared to the pure ES-PANI.