Synergetic optimization of thermal conductivity and breakdown strength of boron nitride/poly (vinylidene fluoride) composite film with sandwich intercalated structure for heat management in flexible electronics

Polymer-based thermal management materials with common homogeneous composition cannot meet the needs of both fast heat transfer and resistance to high-voltage breakdown, due to the coupling of the above two interrelated properties. Thus, a sandwich intercalated structure design is proposed to combine a novel boron nitride (BN)/poly (vinylidene fluoride) (PVDF) composites with synergistically improved thermal conductivity and breakdown strength in this study. Herein, the micro-BN/PVDF is constructed as the outer layer due to the contribution of orientated micro-BN to high thermal conductivity. Attributed to the confinement of interfacial charge in BN nano-sheets (BNNS)/PVDF layer, it is inserted into the micro-BN/PVDF homogenous composite to improve the breakdown strength. The obtained sandwich intercalated structure composite exhibits both high in-plane thermal conductivity (18.4 Wm(-1) K-1) and breakdown strength (96.7 kV/mm) at an equivalent filler loading about 40 wt%. In addition, the thermal management capability of the sandwich structure film is further demonstrated when used as substrate for the heat dissipation of a printed resistor, and a maximum temperature drop of 16 degrees C is exhibited, indicating much potential for thermal management application in flexible electronics.