Heterostructured Alumina/Boron Nitride Nanosheets for Thermal Management of Poly(dimethylsiloxane)

The development of heterostructures offers an effective method for influencing thermal transport mechanisms. This work presents the preparation of heterostructured, thermally conductive alumina nanosphere@boron nitride nanosheet (f-A@B) fillers that resemble "sesame crackers" using the in situ approach. Benefited from the synergistic effect of zero-dimensional (0D) alumina/two-dimensional (2D) boron nitride nanosheet (BNNS) heterostructures in which alumina and BNNS are boned at the interface, the f-A@B/poly(dimethylsiloxane) (PDMS) nanocomposites presented excellent heat dissipation efficiency. The in situ method of uniformly connecting alumina to the BNNS interlaminar is essential for supplying a heat conduction channel. At a mass fraction of 30 wt % f-A@B, the f-A@B/PDMS nanocomposite presents the optimal thermal conductivity (κ) of 3.72 W m–1 K–1, a 1279% increase over pure PDMS. The modified Hashin–Shtrikman (MHS) model verifies and explains the experimental results, suggesting that the reduced filler-to-filler interfacial thermal resistance accounts for the construction of the f-A@B heterostructure. Meanwhile, the as-prepared composites also exhibit exceptional volume resistivity up to 2.2 × 1013 Ω cm, which is 4 orders of magnitude greater than the critical resistance for electrical insulation (109 Ω cm). The composites with superior thermal conductive and electrical insulating properties may open up future opportunities in electrical packaging and thermal management.