Interface Dominated Dielectric Response of PS-Fe₃O₄ Patchy Microspheres

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-Fe₃O₄) 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-Fe₃O₄ patchy microspheres by Pickering emulsion polymerization using Fe₃O₄ particles as a solid stabilizer. The microstructure, composition, morphology, dielectric, and thermal properties of the synthesized patchy PS-Fe₃O₄ particles were investigated. The dielectric permittivity (k) of the neat PS increased from ∼2.9 to ∼14.8 after decorating with Fe₃O₄ particles. Impedance response of the patchy microspheres shows that the interface of PS-Fe₃O₄ stores more charges than bulk PS-Fe₃O₄. 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.