Interface Dominated Dielectric Response of PS-Fe3O4 Patchy Microspheres

Abstract

Polymeric-inorganic interface plays a vital role in enhancing dielectric properties of patchy microspheres, Janus particles, and nanocomposites. We performed the computational modeling and simulations along with experiments to understand the phenomena behind the improved dielectric permittivity of polystyrene-iron oxide (PS-Fe<inf>3</inf>O<inf>4</inf>) patchy microspheres. We addressed the fundamental insights into the role of the interfacial region on the dielectric properties. Based on the experimental outcomes and computational simulations on dielectric behavior including polarization and electric field formation, we propose a new mechanism of charge buildup at the interface. Computational results reveal that the creation of interface bound-charges at the inorganic-polymeric interface is responsible for the improved dielectric properties. We also fabricated PS-Fe<inf>3</inf>O<inf>4</inf> patchy microspheres by Pickering emulsion polymerization using Fe<inf>3</inf>O<inf>4</inf> particles as a solid stabilizer. The microstructure, composition, morphology, dielectric, and thermal properties of the synthesized patchy PS-Fe<inf>3</inf>O<inf>4</inf> particles were investigated. The dielectric permittivity (k) of the neat PS increased from ?2.9 to ?14.8 after decorating with Fe<inf>3</inf>O<inf>4</inf> particles. Impedance response of the patchy microspheres shows that the interface of PS-Fe<inf>3</inf>O<inf>4</inf> stores more charges than bulk PS-Fe<inf>3</inf>O<inf>4</inf>. The dielectric behavior of patchy microspheres can be engineered by tuning the shape and position of the patches. The present studies on polymer-inorganic interface provide some insights into the mechanisms that control dielectric permittivity and nonlinear conduction in an applied electric field. © © 2019 American Chemical Society.