Multiwalled Expanded Graphite Coated with Nanometer-Thick Silica Layers for Thermal Management

Thermal management materials utilized in electronic devices are vital components of both future electronics such as flexible electronics and technologies including artificial intelligence. In this work, nanosilica-coated multiwalled expanded graphite (EG-SiO2) is synthesized via a solgel method and subsequently incorporated into the VMQ matrix. The less stiff nanosilica intermediate shell on the EG alleviates the modulus mismatch between the EG and VMQ and improves their interaction. Consequently, the thermal conductivity of the EG-SiO2-VMQ composites is increased by 394% (0.89 Wm–1 K–1) and 705% (1.45 Wm–1 K–1) compared to pure VMQ (0.18 Wm–1 K–1) at low filler loadings of 5 and 10 wt%, respectively. In addition, the composites have intermediate insulation properties (1012 Ω·cm). This is because the SiO2 nanolayer on the EG surface can inhibit electron transfer in the composites and act as an interception point for the conductive path. This work demonstrates that EG-SiO2-VMQ has enormous potential for use in fabricating polymer composites with high thermal conductivity and outstanding insolation capability, which can be utilized in aerospace, telecommunications, and mobile electronic devices.