Morphology-controllable graphene-TiO2 nanorod hybrid nanostructures for polymer composites with high dielectric performance

High permittivity polymer-based materials are highly desirable due to their inherent advantages of being easy to process, flexible and light weight. Herein, a new strategy for the development of polymer composites with high permittivity and low dielectric loss has been proposed based on morphology-controllable graphene-TiO2 nanorod hybrid nanostructures. These hybrid nanostructures possess large aspect ratio, high surface area and high electric conductivity graphene sheets, which provide ideal electrodes in the construction of microcapacitors. In addition, the morphology-controllable TiO2 nanorod decoration effectively prevents direct contact between the graphene sheets in the composite, which give advantages for forming a large microcapacitor network and suppressing the leakage current. As a consequence, a polystyrene composite with 10.9 vol% graphene-TiO2 nanorod sheets exhibits a very high permittivity of 1741 at 10(2) Hz, which is 643 times higher than the value for pure polystyrene (2.7), and low dielectric loss (tan alpha) of only 0.39. The permittivity of the composites can be controlled by controlling the amount of nanorod decoration on the graphene substrates, which provides a new pathway for tuning the permittivity of polymer composites. We expect that our strategy of controlling filler interface will be applied to acquire more polymer composites with high permittivity and low dielectric loss.