Largely enhanced dielectric and thermal conductive properties of novel ternary composites with small amount of nanofillers

Polymer-based composites with excellent dielectric and thermal conductive properties attract ever-increasing attentions from researchers due to the irreplaceable role in energy storage system and electrical devices. Herein, poly(vinylidene fluoride) (PVDF)-based ternary composites were fabricated by adding small amount of poly(dopamine) coated boron nitride (DBN) and electrochemical exfoliated graphene (EEG) into PVDF matrix. Due to the high degree of π-conjugation and good dispersity of EEG, high dielectric constant could be achieved with a very small addition. Meanwhile, after a small amount of DBN was introduced into the EEG/PVDF system, high dielectric constant, low dielectric loss and excellent thermal conductivity were integrated into the EEG/DBN/PVDF ternary composites due to the synergistic effect of DBN and EEG. Compared with the dielectric constant of 591 and loss of 1.21 for EEG(2.0%)/PVDF, the dielectric constant of the DBN(3.1%)/EEG(2.0%)/PVDF can reach up to 6655 and the dielectric loss can be suppressed below 0.83 at 10 2  Hz. In addition, the thermal conductivity of the ternary composite film can reach up to 1.33 W m -1  K -1 , which is 5.68 times more than that of pure PVDF (0.234 W m -1  K -1 ). This work provides a simple and efficient strategy to exploit novel polymer based composites with excellent dielectric and thermal conductive properties for extensive applications in electronics and energy storage systems.