Dual Network Structures of Polyurethane/Boron Nitride Nanosheets/Alumina for Improved Thermal Management of Polymers

The development of efficient thermally conductive polymer composites is crucial for the performance upgrade of modern electronics. However, the thermal conductivity of polymer composites is dramatically limited by inadequate thermal networks and mechanical properties degradation. Herein, we report the preparation of polydimethylsiloxane (PDMS) composites with dual thermal networks of functionalized boron nitride nanosheets (fBNs) and alumina (Al 2 O 3 ) spheres impregnated in commercial polyurethane (PU) foams. The fBN layers are first assembled hydrothermally onto the surface of tannic acid (TA)-modified PU foam (PT) to form a 3D fBN network, followed by the vacuum infiltration of Al 2 O 3 /PDMS to obtain PT/fBN/Al 2 O 3 /PDMS composites. The thermal conductivity of the composite reaches 3.1 W/mK at 11.5 wt % fBN and 15 wt % Al 2 O 3 loading, with a 2285% enhancement compared to that of pure PDMS. Moreover, the resulting composite shows excellent practical performance in the heat dissipation simulation of integrated chips, demonstrating the broad prospect for thermal management applications. Additionally, the mechanical properties of the composite are significantly improved. This work provides a promising strategy for the production of polymer-based high-performance thermal management materials.