Bimodal Polymer Brush Core–Shell Barium Titanate Nanoparticles: A Strategy for High-Permittivity Polymer Nanocomposites

This paper presents a novel strategy to modify the surface chemistry of barium titanate (BaTiO3, BT) with a bimodal population of oligothiophene polymer brushes using step-by-step reversible addition–fragmentation chain transfer (RAFT) polymerization. Compared with a previous strategy based on monomodal surface-tethered brushes, these hybrid nanoparticles, BaTiO3 coated with bimodal oligothiophene polymer brushes, demonstrate extremely good dispersion behaviors as dielectric nanofillers in a matrix of oligothiophene polymers. These nanodielectric composites exhibit greatly improved dielectric performance and maintain linear displacement–polarization (D–E) profiles under high applied electric fields. This promising bimodal strategy could be generalized to a variety of nanoparticles for the development of novel dielectric nanocomposite systems.