Achieving thermally conductive low loss PVDF-based dielectric composites via surface functionalization and orientation of SiC nanowires

Semi-conductive silicon carbide (SiC) nanowires were amino-functionalized to achieve better dispersion in poly(vinylidene fluoride) (PVDF) matrix. It was found that PVDF based composites with amino-functionalized SiC (f-SiC) nanowires exhibited lower loss tangent than their counterparts with bare SiC nanowires, especially at a filler loading of 13.8 vol%. The loss tangent at 1 kHz of PVDF/f-SiC nanowires (86.2/13.8, v/v) composite is only 0.048, which is nearly one quarter of that of its counterpart with bare SiC nanowires. The nearly one order of magnitude lower AC conductivity at 1 kHz is responsible for the remarkable decrease of the loss tangent, since the interlacing of f-SiC nanowires was avoided via their parallel orientation, facilitated by the enhanced interfacial interaction. In addition to the low loss, the PVDF/f-SiC nanowires (86.2/13.8, v/v) composite exhibited about twofold increase of the dielectric permittivity at 1 kHz, compared to neat PVDF. Moreover, the thermal conductivity of PVDF/f-SiC nanowires (86.2/13.8, v/v) composite was increased to twice that of neat PVDF. The thermally conductive, high dielectric permittivity, and low loss PVDF/f-SiC nanowires composites may find potential applications in capacitors for microelectronics.