Synthesis and dielectric properties of polyimide/hollow silica nanofiber composite

Organically modified hollow silica (SiO2) nanofibers (m-HSNFs) were synthesized via an effectively combined method of electrospinning, high-temperature calcination and chemically modified using 3-aminopropyl(triethoxysilane) (APTEOS). The m-HSNFs were served as a core for the fabrication of polyimide composites using two-step polymerization. Fourier transform infrared (FTIR), field-emission scanning electron microscopy, and transmission electron microscopy were used to characterize the chemical structure and morphology of the fabricated composites. These FTIR results indicate that the polyamic acid was successfully synthesized and converted into polyimide by two-step polymerization process. The degradation temperatures of the nanocomposite materials slightly increase as the loadings of m-HSNF increase. This phenomenon is contributed to the existence of higher thermal stability m-HSNF in the polyimide matrix, resulting in the increase of the thermal stability of composites. The dielectric constants of the nanocomposite materials measured at 28 GHz and 38 GHz decrease as the presence of fluorine-containing groups in dianhydride monomers and the loadings of m-HSNF increase. This result is probably contributed to the increase of free volume with the presence of trifluoromethyl groups and m-HSNF.

Automated summary

Organically modified hollow silica nanofibers were synthesized and used as the core for polyimide composites. The composites were characterized using FTIR, SEM, and TEM. The results showed successful synthesis of polyimide through two-step polymerization, and an increase in thermal stability and decrease in dielectric constants with the addition of modified hollow silica nanofibers.