High‐Performance h‐ <scp>BN</scp> / <scp>PDMS</scp> Thermal Interface Composites Enabled by Polydopamine and <scp>KH550</scp> Dual Surface Modification

ABSTRACT The efficient heat dissipation in modern electronics creates an urgent need for high‐thermal‐conductivity polymer‐based thermal interface materials. A key challenge in developing such materials lies in the incorporation of functional fillers. Hexagonal boron nitride (h‐BN) is a promising thermally conductive filler for enhancing the thermal conductivity of the polymer matrix; however, its dispersion and interfacial compatibility with polymers are hindered by strong agglomeration and chemical inertness. Herein, we develop a dual‐modification strategy for h‐BN using polydopamine (PDA) and the silane coupling agent KH550. A PDA layer is first coated onto h‐BN via self‐polymerization, followed by KH550 grafting, yielding the functionalized filler (KBN). This approach significantly improves the dispersion of h‐BN in a polydimethylsiloxane matrix and enhances the filler‐matrix interfacial interaction. The resulting composite with 40 wt% KBN loading achieves a high thermal conductivity of 1.48 W m −1 K −1 , much higher than that of pure polydimethylsiloxane. This work provides an effective route for developing high‐performance TIMs for advanced electronic packaging applications.