Enhanced dielectric performance of polyimide composites with modified sandwich-like SiO2@GO hybrids

High-dielectric-constant (high-k) polymer nanocomposites are demonstrated to show great promise microelectronics industry. In this work, sandwich-like SiO2 encapsulated graphene oxide hybrids (SiO2@GO) were fabricated throng a sol gel method to enhance the dielectric properties of PI. Series of analysis, such as X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that SiO2 were successfully grafted onto the surface of GO and formed a sandwich-like core shell structure hybrids. Then, polyimide (PI) composites filled with SiO2@GO were prepared via in-situ polymerization method. A dielectric constant of 73 (40 Hz) was obtained for SiO2@GO/PI composites as the fraction of SiO2@GO was 20 wt%. In order to improve the dielectric properties of composite, two kinds of coupling agents, 3-aminopropyl triethoxysilane (APTS) and 3-glycidoxypropyltrimethoxysilane (GPTS), were used to modify the surface of SiO2@GO. GPTS-SiO2@GO/PI composite had an increased dielectric constant of 79 and a decreased loss of 0.25 at 40 Hz. The significantly enhanced dielectric performance of GPTS-SiO2@GO/PI composite was caused by the good dispersion of GPTS-SiO2. In addition, the different dielectric performance of composites modified by different coupling agent was also discussed. This work could help researchers further understand the mechanism of fillers' interface on the dielectric properties of composites. (C) 2017 Elsevier Ltd. All rights reserved.