Electrical field influence on molecular mass and electrical conductivity of polyaniline

Abstract

We have described the primary studies on the conductivity and molecular weight of polyaniline in an electric field as it is used in a field effect experimental configuration. We report further studies on doped in-situ deposited polyaniline. First we have chemically synthesized polyaniline by ammonium peroxodisulfate in an acidic solution, with aqueous, organic and emulsion conditions at different times. Next, we measured mass and conductivity and obtained the best time of polymerizations. Then, we repeated these reactions under different electrical fields in constant time and measured mass and conductivity. The polyaniline is characterized by gel permeation chromatography (GPC), UV-visible spectroscopy and electrical conductivity. Polyanilines with high molecular weight are synthesized under electric field M w = (5.2–6.8) × 105, with M w/M n = 2.0–2.5. The UV-visible spectra of polyanilines oxidized by ammonium peroxodisulfate and protonated with dodecylbenzenesulfonic acid (PANi-DBSA), in N-methylpyrolidone (NMP) show a smeared polaron peak shifted into the visible. Electrical conductivity of polyaniline has been studied by four-probe method. The conductivity of the films of emeraldine protonated by DBSA cast from NMP is higher than 500 S/cm under (10 kV/cm2 of potential) electric field and shows an enhanced resistance to ageing. Next, we carried chemical polymerization at the best electric field at different times. Finally, the best time and amount of electric field were determined. Polymers synthesized under an electric field probably have better physical properties regarding the existence of less branching and high electric conductivity.