Synthetic preparations and physical and electrical properties of main chain type thermotropic liquid crystalline polyimide/SiO2 nanocomposites

Abstract Two kinds of monomers, 1,3‐bis[4‐(4′‐amino‐Phenoxy)cumyl]benzene (BACB) and pyromellitic dianhydride were used to synthesize the Liquid Crystalline Polyamic acid—a precursor (LCPAA) of Liquid Crystalline Polyimide (LCPi). The nanohybrid films were successfully prepared by the sol–gel reaction. Tetraethoxysilane (TEOS) (99%)–ethanol (99.8%) solution was added to LCPAA solution. The hybrid films were made by the hydrolysis–polycondensation of TEOS–ethanol in the LCPAA solution. When water and the solvent were removed completely, the hybrid films were obtained. The functional group and chemical structure were characterized by FTIR. We employed a number of instruments to understand whether the nano‐SiO2 particle was introduced into the polymer matrix and enhanced the thermal properties and mechanical strength. The liquid crystalline phase of the LCPi and LCPi/SiO2 hybrid films was observed by POM. TGA and DSC were used to test the thermal properties. The crystallization and liquid crystal phase analyses were carried out by XRD. The elemental analysis was employed to measure the 1,3‐bis[4‐(4′‐nitrophenoxy)cumyl)]benzene and BACB monomers. Besides, the cross section at morphology of the materials was observed with an FESEM. The electrical properties of hybrid films were measured by the high resistance analysis and dielectric constant analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1688–1704, 2006