Low loss and high dielectric constant poly(methyl methacrylate)/BaTiO3 nanocomposites prepared by in situ atom transfer radical polymerization

Poly(methyl methacrylate) (PMMA) nanocomposites containing BaTiO₃ were prepared by in situ atom transfer radical polymerization (ATRP). The nanocomposites show significantly increased dielectric constant when compared with the pure PMMA, whereas the dielectric loss of the nanocomposite is kept at the same low level as that of the pure PMMA. For example, at 1000 Hz, the dielectric constant increases from 6.9 for the nanocomposite containing 15 vol% BaTiO₃ to 15 for the nanocomposite with 32 vol% BaTiO₃, while the dielectric loss is almost independent on the BaTiO₃ content and has a low value of 0.045. ¹H NMR spectra confirmed the chemical structure of PMMA shell on the surface of BaTiO₃ nanoparticles. Scanning electron microscopy (SEM) revealed that the BaTiO₃ nanoparticles are well dispersed in the nanocomposites.