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 (<i>D</i>–<i>E</i>) 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