Preparation, Characterization, and Conductivity of Polyaniline Doped with 12-Tungstoboric Acid

Abstract

The Keggin type 12-tungstoboric acid (H₅BW₁₂O₄₀) was prepared. Aniline was oxidized in an aqueous solution of H₅BW₁₂O₄₀ to synthesize a series of polyanilines doped with the 12-tungstoboric acid (PANI-[H₅BW₁₂O₄₀]), using ammonium persulfate as an oxidant. The effects of the initial weight ratio x (x) of H₅BW₁₂O₄₀ to aniline on the properties of PANI-[H₅BW₁₂O₄₀] were investigated by FTIR, UV-vis, XRD, and conductivity measurement. The results showed that PANI in PANI-[H₅BW₁₂O₄₀] was in the emeraldine salt state, and the 12-tungstoboric anions were incorporated into the chains of PANI more and more with increasing values of x. The oxidation degree of PANI in PANI-[H₅BW₁₂O₄₀] was strongly dependent on x. As the weight ratio x reached 0.040, the oxidation degree of PANI in PANI-[H₅BW₁₂O₄₀] increased obviously. The reason that electrical conductivity of PANI-[H₅BW₁₂O₄₀] decreased sharply at x was attributed to the increase of the oxidation degree resulted by the excess of H₅BW₁₂O₄₀ used in the preparation.

Keywords:

• conductivity
• doping
• FTIR
• polyaniline
• XRD
• 12-tungstoboric acid

Funding

This work was supported by National Natural Science Foundation of China (NSFC 10774076), Natural Science Fund for Colleges and Universities in Jiangsu Province (09KJB140003 and 11KJB480003), and Open Project M25021 of the National Laboratory of Solid State Microstructures in Nanjing University.