Covalent‐Bond Modified Boron Nitride for High‐Temperature Poly(Ether Ether Ketone) Composites: Enhancement of Thermal Conductivity and Mechanical Properties by Interfacial Strengthening

ABSTRACT Interface thermal resistance is the key factor in influencing the thermal conductivity of filler‐reinforced composites. Building a covalent‐bond bridge between the resin and filler effectively reduces the interface thermal resistance by creating thermal transmission pathways. A covalent‐bonded poly (ether‐ether‐ketone)/boron nitride (PEEK/BN) composite (i‐PEEK/BNNS‐FOH) was prepared by functionalizing BN and incorporating it into the in situ polymerization process. With an addition of 30 wt% functionalized BN, the thermal conductivity of i‐PEEK/BNNS‐FOH reached 1.79 W m ⁻¹ K ⁻¹ , an increase of 12% over ungrafted PEEK/BN. Foygel's model calculations proved that the modification of BN reduced interface thermal resistance by 48%. Additionally, the improved interface contributed to better mechanical properties, reaching a tensile strength of 97 MPa with a 10 wt% filler addition. This covalent‐bond bridging strategy highlights modified BN fillers for high‐temperature applications and an efficient method for the preparation of thermally conductive special engineering plastics.