Construction of 3D boron nitride nanosheets/silver networks in epoxy-based composites with high thermal conductivity via in-situ sintering of silver nanoparticles

Polymer-based thermal conductive composites (PTCs) with good thermal and mechanical properties are highly appreciated in the thermal management of modern electronic devices. However, the heat transfer property of particle-filled PTCs is severely limited by the thermal resistance at both filler-matrix and filler-filler interfaces. Intensive efforts have been taken to enhance the filler-matrix interface, however, the effect of filler-filler thermal contact resistance on the heat transfer properties of PTCs is still not very clear. In this work, continuous thermal conductive networks with good filler-filler interface contact are formed in epoxy composites via the in-situ sintering of silver nanoparticles on the surface of boron nitride nanosheets (BNNS). In this composites, homogeneously dispersed and well exfoliated BN nanosheets are bridged to each other via the sintered AgNPs located at the BNNS and a 3D boron nitride nanosheets network is formed with solid Ag junctions lying in between. After thermal sintering process, the thermal conductivity of EP/BNNS@AgNPs composite with the 3D boron nitride nanosheets network increase from 0.95 W/m.K to 1.13 W/m.K at the filler loading of 20 wt%, which indicates that merged AgNPs are used as thermal transport junctions to reduce the thermal contact resistance within 3D BNNS networks. The present strategy provides an effective route for developing high-performance PTCs.