Flexible and thermally conductive epoxy‐dispersed liquid crystal composites filled with functionalized boron nitride nanosheets

Abstract In view of the problem of heat accumulation in electronic devices, the development of new composites with high thermal conductivity (TC) is the current research focus. Nowadays, improving TC often lead to inevitable deterioration of the mechanical properties of materials. In this work, the E‐functionalized boron nitride nanosheets ( f ‐BNNS)/liquid crystal monomer (LCM)/Epoxy‐thiol films with high TC were prepared by using flexible epoxy‐thiol polymer as matrix and LCM and f ‐BNNS as thermal fillers via high voltage orientation molding. The epoxy‐thiol polymer possessed high intrinsic TC due to the regular arrangement of molecular chains and the f ‐BNNS showed favorable dispersibility because of the modification by isopropyl tri(dioctylpyrophosphate) titanate (ITDPT). The results show that TC of E‐ f ‐BNNS/LCM/Epoxy‐thiol films with 30 wt% f ‐BNNS content achieves 1.65 W/m·K and is 511.11% higher than that of pure epoxy‐thiol polymer (0.27 W/m·K). The tensile strength and elongation at break increase to 24.9 MPa and 47.41%, respectively. The favorable results are attributed to the ordered arrangement of f ‐BNNS and molecular chains, resulting from the hydrogen‐bonding interaction between OH group in f ‐BNNS, LCM and epoxy‐thiol polymer. This research provides a simple and feasible method for preparing flexible epoxy polymer films with high TC. Highlights The functional BNNS was achieved by isopropyl tri(dioctylpyrophosphate) titanate. Effects of matrix thermal conductivity on films thermal conductivity are probed. High voltage orientation molding are used for preparing epoxy composite films. The films demonstrate excellent thermal conductivity and favorable tensile strength.