Polydopamine-assisted silver-coated spherical boron nitride as dual functional filler for thermal management and electromagnetic interference shielding

Developing high-performance multifunctional fillers for polymer filling is of significant importance for thermal management and electromagnetic interference (EMI) shielding in the electrical and electronic fields. In this work, a novel dual-functional filler of silver-coated spherical boron nitride (Ag@s-BN) was first synthesized via the electroless chemical deposition method with the aid of polydopamine and then used to improve the thermal conductivity and EMI shielding performance of the silicone rubber (SR). It is found that the Ag@s-BN filled SR composites show remarkable improvement in thermal conductivity compared to raw s-BN filled composites at the same loading fraction. At 23.3 vol% Ag@s-BN, the SR/Ag@s-BN composite exhibits a thermal conductivity of 1.53 W m⁻¹ K⁻¹, which is improved by 48.5 % and 806.8 % compared to the SR/s-BN composite and pure SR, respectively. Meanwhile, the remarkably improved electrical conductivity of the SR/Ag@s-BN composite at 23.3 vol% Ag@s-BN leads to an EMI shielding effectiveness of 20.9 dB that already reaches a commercial standard. Moreover, due to the high sphericity and smooth surface of Ag@s-BN, the Ag@s-BN filled SR mixture before curing possesses good processability and thus is suitable for the potting processes. Overall, this work provides a novel strategy for developing polymer composites with both thermal conductivity and EMI shielding properties.