Synthesis of semiconducting poly(diphenylamine) particles and analysis of their electrorheological properties

Abstract

Poly(diphenylamine) (PDPA) particles were synthesized as a novel semiconducting electro-responsive electrorheological (ER) material by a chemical oxidative polymerization process and their ER characteristics were investigated at various electric fields. Surface morphology of these N-aryl-substituted polyaniline-derived PDPA particles was examined by scanning electron microscopy and their chemical structure and thermal properties were confirmed by Fourier-transform infrared spectroscopy and thermogravimetric analysis, respectively. Their susceptibility to electric fields and the chain formation of dispersed particles were observed directly using optical microscopy. Rheological analysis of the PDPA-based ER fluid was performed using a combination of steady shear and oscillation tests in a Couette-type rotational rheometer with a high-voltage power supply. The measurements were performed in controlled shear stress and shear rate modes under the varied electric field strengths. The Cho–Choi–Jhon model was found to determine the stress behavior more clearly. Dielectric analysis provided additional information about the electrical polarization properties and thus also the ER performance of the PDPA-based ER fluid.