Interfacial Regulation and Thermal Conductivity of Geraniol-Silane-Modified BN/MVQ Composites

Hexagonal boron nitride (h-BN) is widely used as a thermally conductive filler in methyl vinyl silicone rubber (MVQ), but its surface inertness and poor interfacial compatibility limit further thermal-conductivity enhancement. In this work, a geraniol-derived silane modifier (Ger-IPTMS) was synthesized and grafted onto hydroxylated BN to prepare Ger-BN for MVQ composites. FTIR, XPS, TGA, SEM/EDS, and XRD confirmed the introduction of Ger-IPTMS-related surface species while preserving the BN crystal structure, with an apparent grafting ratio of 1.28%. Laser-diffraction and BET analyses showed that the modification did not markedly change the filler size or accessible surface area. At 35 wt % filler loading, the thermal conductivity increased from 1.23 W·m –1 ·K –1 for BN/MVQ to 1.60 W·m –1 ·K –1 for Ger-BN/MVQ, corresponding to a 30.1% enhancement, and reached 1.82 W·m –1 ·K –1 at 40 wt %. The apparent thermal contact resistance decreased by 17.6% after modification. At 20 wt %, tensile strength increased from 0.87 to 1.34 MPa. MD simulations indicated lower free volume, higher binding energy, and restricted chain mobility, supporting improved interfacial compactness and filler–matrix interaction.