Multifunctional silanized silica nanoparticle functionalized graphene oxide: polyetherimide composite film for EMI shielding applications

Abstract

Synthesis of graphene oxide (GO) was done using graphite powder by Hummer’s modified method and it was functionalized using silanized silica nanoparticle. Various weight percentage of functionalized graphene oxide (FGO) in polyetherimide (PEI) matrix (0.5–3 wt%) nanocomposite films were synthesized using solution based method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies confirm the functionalization and partial reduction of GO. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies demonstrated the nanostructure of GO, FGO and PEI–FGO nanocomposite films. The electromagnetic interference (EMI) shielding effectiveness in comparison to pure polyetherimide (2–3 dB), nanocomposite with 1.5 wt% FGO loading exhibits upto 21–23 dB at frequency range 8–12 GHz. Dynamic mechanical analysis (DMA) elucidate the improvement of glass transition temperature and storage modulus (E′) of the PEI–FGO nanocomposite films. Variation in different experimental parameters such as frequency, temperature and filler loading were used to analyze the dielectric properties of the PEI–FGO nanocomposite films. Dielectric constant increases seven times and dielectric loss decreases 14 times for nanocomposites with 1.5 wt% FGO loading in PEI matrix as compared to pure polyetherimide. The bandgap decreases slightly for PEI–FGO composite due to an intermediate band in PEI band structure by FGO. The nanocomposite films also exhibited good dielectric, mechanical properties and excellent EMI shielding effectiveness at wide range of frequency and temperature.