Preparation and characteristics of polyimide/CaMoO4 nanocomposites with enhanced dielectric performance and thermal stability

The polyimide/CaMoO4 nanocomposites were successfully prepared by ex-situ polymerization. (3-Aminopropyl) triethoxysilane (KH550) was used as coupling agent to disperse the CaMoO4 nanoparticles in polyimide matrix homogeneously. To characterize the structure and properties of the obtained nanocomposites, Scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, dielectric properties and thermal stability were studied. It was observed that the CaMoO4 nanoparticles were dispersed homogeneously in the polyimide matrix without obvious aggregation. The results show that nano-sized CaMoO4 will improve dielectric constant and decrease dielectric loss of the nanocomposites in the relatively high-frequency region (>10 kHz). And the nanocomposite with excellent dielectric properties of e = 3.04, δ = 8.0 × 10−3 was obtained after doping 2.5 wt% nano-sized CaMoO4 into polyimides. Dielectric loss of the nanocomposites is reduced in low frequency domain ( 10 kHz). In addition, the thermal stability of the nanocomposites was enhanced from 544 to 651 °C compared to pure polyimide.