TiO2-nanorod decorated carbon nanotubes for high-permittivity and low-dielectric-loss polystyrene composites

Polymer composites with high permittivity and low dielectric loss are highly desirable in electronic and electrical industry. Adding conductive fillers could significantly increase the permittivity of a polymer. However, polymer composites containing conductive fillers often exhibit very high dielectric loss due to their large electrical conduction or leakage currents. In this work, by engineering TiO₂-nanorod-decorated multi-walled carbon nanotubes (TD-CNTs), polystyrene (PS) composite with high permittivity and low dielectric loss have been successfully prepared. The composite containing of 17.2 vol.% TD-CNTs has a permittivity of 37 at 1 kHz, which is 13.7 times higher than that of the pure PS (2.7), while the dielectric loss still remains at a low value below 0.11. The dielectric properties of the composites are closely related to the length of CNTs and the loading level of TiO₂-nanorods on the CNT surfaces.