We fabricated a novel core-shell-type microsphere-based electrorheological (ER) composite material using poly(diphenylamine) (PDPA) as an electro-responsive coating layer onto polystyrene (PS) particles of controlled size and morphology. The coating of the core particle with a semiconducting shell was successfully achieved under a controlled environment to attain compact wrapping of surfaces, as confirmed by morphological analysis by using scanning electron microscopy and transmission electron microscopy. The chemical composition and thermal stability of the particles were investigated by Fourier-transform infrared spectroscopy and thermogravimetric analysis, respectively. The rheological properties of the PS/PDPA-based ER fluid were analyzed via both steady shear and dynamic oscillation tests performed under various electric field strengths. Further characterizations of both the susceptibility of flow behavior to the electric fields and the electrical polarization property of the PS/PDPA-based ER fluid were performed by using an LCR meter to provide additional information supporting its ER performance, which was determined to follow a conduction model with a slope of 1.5. (C) 2017 Elsevier Ltd. All rights reserved.