Fabrication of Thermal Conductivity Enhanced Polymer Composites by Constructing an Oriented Three-Dimensional Staggered Interconnected Network of Boron Nitride Platelets and Carbon Nanotubes.

The orientation of ultrahigh aspect ratio thermally conductive fillers can construct a heat transfer path to enhance the thermal conductivity of composite materials effectively with low filler loading. Nevertheless, single orientation (vertical or horizontal) limited the application of these materials when there was the need for isotropic heat transferring. Here we report a novel strategy to prepare thermally conductive flexible cycloaliphatic epoxy resin nanocomposites with an oriented three-dimensional staggered interconnected network of vertically aligned h-BN (hexagonal boron nitride) platelets and randomly dispersed CNT-NH (aminated carbon nanotubes). In this structure, h-BN platelets coated with magnetic particles could respond to the external magnetic field; however, the CNT-NH couldn't. The obtained composites exhibited both through-plane (0.98 ± 0.037 W/m·K) and in-plane (0.99 ± 0.001 W/m·K) thermal conductivity enhancement at low h-BN loading of 30 wt %, and also presented excellent electrical insulating properties (<1.2 × 10 S/cm). In addition, the equal value of thermal conductivity of two directions (in-plane and through-plane) was shown when the content of h-BN was about 26.43 wt % and of CNT-NH was 2 wt %, displaying no difference between the thermal conductivity of two directions (in-plane and through-plane). The infrared imaging tests showed the outstanding heat dissipation capability of the composites by capturing the surface temperature variations of a heater with the composites as the heat dissipating material.