Leipeng Liu

Polyimide composites composed of covalently bonded BaTiO3@GO hybrids with high dielectric constant and low dielectric loss

Novel flexible three-phase high-k polyimide (PI) composites were fabricated by the incorporation of covalently bonded BaTiO3@graphene oxide (BaTiO3@GO) hybrids in which the BaTiO3@GO hybrids were prepared by the reaction of amino modified BaTiO3 particles and GO. A series of analyses, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman and XRD demonstrated that amino modified BaTiO3 particles were successfully grafted onto the surface of GO. A dielectric constant as high as 285 (100 Hz), which was eighty times that of a pure PI film, a lower dielectric loss as low as 0.25 and high-frequency-shift dielectric relaxation were obtained for BaTiO3@RGO/PI composites as the fraction of BaTiO3@GO was 20 wt% (the corresponding volume fraction is 8 vol%). The flexible, high-k BaTiO3@RGO/PI composites have promising potential applications for capacitors and electronic devices in the fields of micro electron.

Optical-electric properties of poly(amic acid) composite films with a low content of thermotropic liquid crystals

Poly(amic acid) composite films with the thermotropic liquid crystal, 10-cholesteroxy-10-oxocaproic acid (COOA) were developed. The composites could still show liquid crystal behavior at low COOA loading (as low as 3 wt%) due to the phase separation under the induction of temperature. The synergistic reaction of the interaction of PAA with COOA and the arrangement of COOA endowed the films with strong fluorescence and a higher temperature shifted liquid crystal phase. Even more, the dielectric constant of the composites was enhanced. The composites were multifunctional optical-electric materials.