Preparation, characterization and dielectric properties of polyetherimide nanocomposites containing surface‐functionalized BaTiO 3 nanoparticles

Polyetherimide (PEI)/hydroxyl‐functionalized barium titanate (BaTiO 3 ) 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 (H 2 O 2 ) could efficiently derive hydroxyl groups on the surface of BaTiO 3 nanoparticles. The strong interaction between the hydroxyl‐functionalized BaTiO 3 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 BaTiO 3 nanoparticles (50 vol% BaTiO 3 loading) showed an increased dielectric permittivity of 52.78 at 1 kHz compared with the dielectric permittivity (33.87) of PEI/raw BaTiO 3 composite. The loss tangent was still low (less than 0.03) when the content of hydroxyl‐functionalized BaTiO 3 was 50 vol%. For PEI/BaTiO 3 nanocomposites, the frequency and temperature dependences of the dielectric properties were significantly reduced through functionalizing the surface of BaTiO 3 nanoparticles with H 2 O 2 . Different theoretical approaches were employed to predict the effective permittivity of the nanocomposite systems and the results are compared with the experimental results. Copyright © 2012 Society of Chemical Industry