Preparation, characterization and dielectric properties of polyetherimide nanocomposites containing surface-functionalized BaTiO3 nanoparticles

Polyetherimide (PEI)/hydroxyl-functionalized barium titanate (BaTiO3) nanocomposite films were successfully prepared through solution-casting followed by subsequent thermal imidization. The results of Fourier transform infrared spectroscopy confirmed that the chemical treatment with hydrogen peroxide (H2O2) could efficiently derive hydroxyl groups on the surface of BaTiO3 nanoparticles. The strong interaction between the hydroxyl-functionalized BaTiO3 and the PEI matrix greatly enhanced the particle dispersion as well as the interfacial adhesion, as evidenced by scanning electron microscopy. The PEI nanocomposite with hydroxyl-functionalized BaTiO3 nanoparticles (50 vol% BaTiO3 loading) showed an increased dielectric permittivity of 52.78 at 1 kHz compared with the dielectric permittivity (33.87) of PEI/raw BaTiO3 composite. The loss tangent was still low (less than 0.03) when the content of hydroxyl-functionalized BaTiO3 was 50 vol%. For PEI/BaTiO3 nanocomposites, the frequency and temperature dependences of the dielectric properties were significantly reduced through functionalizing the surface of BaTiO3 nanoparticles with H2O2. Different theoretical approaches were employed to predict the effective permittivity of the nanocomposite systems and the results are compared with the experimental results. Copyright (c) 2012 Society of Chemical Industry