Highly thermally conductive polyvinyl alcohol/boron nitride nanocomposites with interconnection oriented boron nitride nanoplatelets

With the development of high power density electronic devices, much more excessive heat is generated, which puts forward higher requirements for the thermal conductivity (TC) of polymer materials. In this study, polyvinyl alcohol (PVA)/boron nitride nanoplatelets (BNNSs) nanocomposites were fabricated with high in-plane TC via the combination of co-electrostatic spinning and spraying and hot-pressing technique. The high TC of the nanocomposites was due to the large lateral size of 2D BNNSs, which was obtained via boric acid-assisted ball milling. Another paramount structural factor is the selective distribution of these BNNSs on the surface of 1D PVA fibres. These interconnected BNNSs are oriented along the in-plane direction after pressing, which construct continuous heat conduction pathways in the nanocomposites. Additionally, the in-plane TC of the nanocomposites shows obvious thickness dependence, reaching 19.99 W/(m·K) with a thickness of 30 μm at BNNSs fraction of 40 wt%; it may be because BNNSs in thinner nanocomposites possess high orientation degree as their rotational freedom decreased.