Highly thermally conductive yet mechanically robust composites with nacre-mimetic structure prepared by evaporation-induced self-assembly approach

Highly thermally conductive and mechanically strong nanocomposites for efficient thermal management have received wide attention because of the rapid development of modern electronics. Boron nitride nanosheet (BNNS) with combined benefits of high thermal conductivity (TC) and good electrical insulation has been considered a promising filler to fabricate thermally conductive nanocomposites. Herein, inspired by biological systems, large-scale and high-performance artificial nacre-like composite composed of BNNS and oxidized cellulose nanocrystal (OCNC) is fabricated through simple evaporation-induced self-assembly (EISA) approach for the first time. Thanks to the template effect of OCNC host, BNNS and OCNC are self-assembled to form an artificial layer-by-layer nacre structure, where OCNC combined with the epoxy-based adhesive agent (AA) serves as the mortar to form a stiff and dense structure. The resulting BNNS-OCNC-AA composite at a relative low BNNS loading of 11.6 vol% exhibits a high in-plane thermal conductivity of 10.9 W/mK as well as the excellent tensile strength of 197.3 MPa, which are prominent compared to other composites fabricated via the various currently established methods under higher filler loadings (13.4 ~ 95 vol%). From the characterization results, we could attribute the multiple properties to the construction of the unique nacre-like structure and the robust interfacial interaction. The artificial nacre-like BNNS composite with excellent thermal and mechanical properties simultaneously has significant potential application for thermal management in flexible and wearable electronics fields.