Facile approach to produce water-dispersible conducting polyaniline powder

Abstract

In this work, electrically conducting polyaniline (PAni) was obtained as a highly water-dispersible powder. The chemical aniline oxidative polymerization was conducted in the presence of poly(styrenesulfonic acid) (PSS) using ammonium peroxydisulfate (APS) as oxidative agent. The effects of aniline concentration and Ani:APS molar ratio on the redispersion capability of PAni.PSS powders were investigated. The purified PAni.PSS powders were redispersed in water and evaluated by UV–vis spectroscopy, field-emission scanning electron microscopy (FE-SEM) and dynamic light scattering (DLS). The electrical conductivity was measured on the dried material by the four-point probe method. As-prepared dispersions were also evaluated for comparative analyses. Conducting PAni.PSS as a powder with remarkable dispersibility and stability in water was obtained using Ani:APS 4:1 and aniline concentration of 0.256 mol.L−1. This material presented electrical conductivity of 10-3 S. cm−1 and granular morphology. Nanoparticles were obtained after sonication in water for only 4 min, with reproducible results. This colloidal dispersion remained stable for at least two months. Further analyses of zeta potential and stability in alkaline medium revealed negatively charged particles without flocculation signs in alkaline pHs for 240 h. At lower aniline concentration (0.032 mol.L−1) particles with 10 nm were obtained, however, not adequate for typical filtration. At Ani:APS 1:1 molar ratio yielded larger particles with heterogeneous distribution and partial precipitation.