Fabrication of polymethyl methacrylate composites with silanized boron nitride by in-situ polymerization for high thermal conductivity

Heat management is considered to be a critical issue for the efficient integration of electronic devices, and the demand for materials with high thermal conductivity is increasing. Therefore, various thermally conductive fillers have been developed to enhance the heat flow in polymer composites. However, boron nitride (BN), a thermally conductive filler has low compatibility with polymer matrix, which causes interfacial phonon scattering and interferes with the heat transfer performance. In this study, BN/polymethyl methacrylate (PMMA) composites with high thermal conductivity were prepared using a simple in-situ polymerization process and a hot-pressing method. The surface of BN was silanized with vinyltriethoxysilane to introduce double bonds, and it was directly linked with the polymer chains during the polymerization step. As a result, at a BN content of 70 wt%, the composite exhibited an obvious thermal conductivity enhancement, with a value that was 17.8 times higher than that of PMMA. In addition, our composites were also compared to other BN/PMMA composites fabricated with conventional melt-mixing and showed higher thermal conductivities.