Enhancing thermal conductivity in polysiloxane composites through synergistic design of liquid crystals and boron nitride nanosheets

Polysiloxane-based thermally conductive composites are essential for electronic heat management, but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency. In this work, a novel liquid crystal crosslinker (LCC) based on biphenyl liquid crystal moieties was synthesized. Liquid crystal polydimethylsiloxane (LC-PDMS) with intrinsic high 7 was prepared by crosslinking vinyl/methyl-hydrogen functionalized PDMS by LCC at its liquid crystal transition temperature, and boron nitride nanosheets (BNNs) with different particle sizes were used to prepare BNNs/LC-PDMS composites. When the mass ratio of LCC to vinyl-terminated PDMS is 2:1, the LC-PDMS exhibitsa well-ordered liquid crystal phase, and its 7|| reachesthe maximum value of 0.34 W (m K)-1 , approximately 1.7 times that of general PDMS (0.20 W (m K)-1 ). The 7|| of BNNs/LC-PDMS composites increases with the addition of BNNs, and when the mass fraction of BNNs reaches 30 wt%, with a 1:9 mass ratio of small BNNs (1 mu m) to large BNNs (10 mu m), the composite achieves the highest 7|| of 12.50 W (m K)-1 , a 68.5% increase compared to BNNs/PMDS composites containing the same amount of BNNs (7.42 W (m K)-1 ). Additionally, BNNs/LC-PDMS composites also demonstrate excellent electrical insulation properties and low density, making them promising candidates for applications in highly integrated electronics fields. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.