Thermal-conductive polymer composites have developed to be a hotspot in academic and industrial fields recently. Both efficient heat transport and superior mechanical properties are of critical significance for high-performance thermal-conductive devices. In this paper, magnetic hexagonal boron nitride (mhBN) with excellent interfacial compatibility is successfully synthesized by dopamine and magnetic co-functionalization, and mhBN-poly(vinylidene fluoride) (mhBN-PVDF) composites with a combination of high thermal conductivity and outstanding mechanical property are achieved due to the integration of excellent interfacial interaction and aligned filler architecture into one material's system. The thermal conductivity increases from 0.35 W/(m K) for the 20 wt % pure BN-PVDF to 0.82 W/(m K) after the dopamine modification and further to 1.43 W/(m K) after alignment. The effective medium approximation model demonstrates that the optimization of mhBN orientation and decrease of thermal resistance are two major factors for the enhancement of thermal conductivity. Moreover, the mhBN-PVDF composites also exhibit excellent tensile strength (168.5 MPa at 15 wt % content) and impact strength (20-30 kJ/m2). The significantly enhanced thermal and mechanical properties result in the excellent heat exchange ability and durability in the heat exchange test, which is important for potential application in the heat exchange industry.
Keywords: aligned structure; boron nitride; dopamine; magnetic modification; mechanical strength; polymer composite; thermal conductivity.