Constructing of strawberry-like core-shell structured Al2O3 nanoparticles for improving thermal conductivity of nitrile butadiene rubber composites

Abstract

In this paper, we have designed strawberry-like core-shell structured aluminum oxide/tannic acid-ferric ion/silver (Al2O3/TA-Fe3+/Ag) nanoparticles (NPs) and incorporated them into nitrile butadiene rubber (NBR) matrix to obtain thermally conductive composites. The tannic acid (TA) provided a strong binding affinity to the surface of Al2O3 NPs and formed a stable octahedral complex with Fe3+. Moreover, the TA layer enhanced interfacial interactions and compatibility between thermally conductive filler and NBR matrix, leading to reduced phonon scattering and decreased interfacial resistance of NBR composites. As a result, the incorporation of Ag NPs on the surface of Al2O3/TA-Fe3+ enhanced the thermal conductivity (λ) of NBR composites. The results revealed that the λ of 50 vol% Al2O3/TA-Fe3+/Ag/NBR composite was 0.90 W/mK, which was 600% of pure NBR (0.15 W/mK). Meanwhile, the dielectric constant (ϵr) of 50 vol% Al2O3/TA-Fe3+/Ag/NBR composite reached up to 12.91 at 102 Hz. However, the volume resistance of all Al2O3/TA-Fe3+/Ag/NBR composites was larger than 1.97 × 1011 Ω mm. Overall, the proposed low-cost and green surface modification method provides novel insights into the design of advanced polymeric composites with high λ for large-scale production.