Comparative morphological and dielectric properties measurements of homopolymer and block copolymer grafted BaTiO3 nanoparticles

The use of one component system of block polymer grafted nanoparticles is expected to prevent nanoparticle aggregation, result in uniform dispersion, and reduce the dielectric mismatch between the nanoparticle and polymer matrix and improve the overall dielectric performance of nanocomposites. In this study, surface-initiated atomic transfer radical polymerization (Si-ATRP) was used to synthesize core-shell barium titanate-poly(methyl methacrylate) (BaTiO₃-PMMA), barium titanate-polystyrene (BaTiO₃-PS) polymer grafted nanoparticle and  ARGET-ATRP  was used to synthesized block copolymer grafted nanoparticles (BaTiO₃-PS-b-PMMA and BaTiO₃-PMMA-b-PS). The molecular weights and dispersities of synthesized homopolymer and BCP nanoparticles were in the range of 31000 g/ml to 150000 g/mol and 1.2 to 1.8, respectively, indicating controlled growth of the polymer on the BaTiO₃ surface. The dielectric study of homopolymer BT-PMMA exhibited improved dielectric constant (3.7 to 9.9), low dielectric loss (< 0.05) with a high breakdown strength (200 to 347 V/µm), resulting in high energy densities (0.82 to 5.2 J/cm³) compared to pure polymer system.  We are currently evaluating the dielectric performance of BT-BCP and results will be used to compare the dielectric performance of BaTiO₃-BCP to that of BaTiO₃-homopolymers single component system.  The matrix-free single-component system can have far-reaching applications in the electronics industry.