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 102 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.