A facile method to fabricate water-dispersible hetero-structured AuNPs@BNNS hybrid filler and its application for enhancing thermal conductivity

Chemical inertness of BNNS seriously restricts its application for fabricating thermally conductive polymer-based composites with uniform dispersion and low interfacial thermal resistance. In this work, by using self-initiated photografting and photopolymerization (SIPGP) method, over 40 wt% polyacrylic acid (PAA) macromolecular chains can be grafted onto BNNS in only 2 h for improving polarity and water dispersibility of BNNS, and the content of grafted PAA can be easily tuned by the reaction time. Furthermore, based on the coordination effect between carboxyl groups of PAA and Au3+/AuNPs, large amount of AuNPs can be immobilized onto BNNS to form hetero-structured AuNPs@BNNS hybrid filler, and such filler is beneficial for decreasing interfacial thermal resistance between fillers, constructing thermally conductive network in relatively lower filler content and improving comprehensive thermal conductivity. Finally, AuNPs@BNNS/NFC composite with only 30 wt% filler can reach in-plane and through-plane thermal conductivities of 19 and 1.22 W/(m·K) simultaneously. Therefore, this study provides a simple and effective method to fabricate water-dispersible and hetero-structured AuNPs@BNNS hybrid filler, which can be used for preparation of high-efficiency thermal management materials for electronic devices effectively.