Synthesis of Sandwich-liked Nanostructure Fillers and Their Use in Different Types of Thermal Composites.

Thermally conductive yet electrically insulating two-dimensional boron nitride nanosheet (BNNS) has been an ideal choice of the enhanced filler for improving thermal properties of polymer-based composites. As a nanofiller with ultra-high aspect ratio, BNNS results in a conspicuous stacking along the planar direction in the preparation of composites, which results in a strong anisotropy of heat transfer and suppresses out-plane thermal dissipation. Thus, it is necessary to facilitate the out-plane heat transfer by building favorable microstructure. Focusing on the structural design of nanofillers itself, here we have fabricated a novel three-dimensional nanofiller with improved out-plane connections. Carbon nanotubes (CNTs) have been grown in-situ on the surface of BNNSs using chemical vapor deposition (CVD). Utilizing this BNNS/CNT as fillers in composites, we have assembled diverse sorts of composites, such as the flexible films, scleroid 3D mats, painted ink, and viscous grease. Simultaneously, their thermal and insulating properties have been evaluated. The results indicate that the BNNS/CNT filler has superior thermal performance over the original BNNS while maintaining a satisfactory electrical resistivity to avoid short-circuits in high-power electronics. Furthermore, the prepared grease used as a thermal interface material shows an impressive heat dissipation performance when being applied on a computer running.