Preparation and properties of polybenzoxazole–silica nanocomposites via sol–gel process

A novel organic/inorganic hybrid material has been prepared through the sol–gel process. A high temperature polymer, polybenzoxazole (PBO), was chosen as the organic phase due to its inherent low dielectric constant and low water absorption. The inorganic phase was generated via sol–gel reaction from a silica precursor, phenyltriethoxysilane (PTEOS). Due to the hydroxyl groups in the PBO precursor backbone and the water release during the cyclization of the precursor, the sol–gel reaction proceeded without the addition of water and any catalyst. After curing at 350 °C, we obtained the PBO/silica nanocomposites. From TEM and SEM photographs, the silica particles dispersed in the PBO matrix were nano-sized. With an addition of 100 wt% of PTEOS, the Tg of PBO was increased 35 °C. The dielectric constant of the hybrid materials increased with the increasing amount of PTEOS.