Silica/Polyurea Composite: Preparation, Characterization and Study of Dielectric Constant

Silica/polyurea composite was prepared after surface modification of silica nanoparticles. Silica/polyurea composite was characterized by Fourier-transform infrared spectroscopy, ultraviolet spectroscopy, X-ray diffraction and transmission electron microscopy. The results indicate that the helical polyurea has been successfully grafted onto the surfaces of the modified silica. Silica/polyurea composite exhibits clearly core–shell structure. The ultraviolet absorption and crystallizability of silica/polyurea are changed due to the shell of helical polyurea, which possesses regular singlehanded conformation and interchain hydrogen bonds. The dielectric constant of silica/polyurea was also investigated. The result indicates that the interfacial interactions between organic shell and inorganic core increase the dielectric constant value being increased to 6.42 for silica/polyurea. The interchain hydrogen bonds of helical polyurea could also be the reason for the increasing of dielectric constant.