Preparation and molecular dynamics simulation of natural rubber thermal conductive composites reinforced with boron nitride modified by a hyperbranched coupling agent

Abstract The applications of thermal interface material (TIM) based on boron nitride (BN)‐filled polymer composites are often constrained by weak interfacial interactions between BN and the polymer matrix. In this work, the hyperbranched polymer (H‐Si69) was synthesized by polycondensation on the surface of BN using a sulfur‐containing coupling agent. The coupling agent modified BN (g‐BN), and natural rubber (NR)/g‐BN composites were prepared with higher thermal conductivity and mechanical properties. The thermal conductivity (0.665 W/mK), tensile strength (19.78 MPa), and elongation at break (1091.8%) of the NR/g‐BN composites with a 19.6% volume fraction of g‐BN were 44.40%, 15.47%, and 29.56% higher than those of the NR/BN composites, respectively. Furthermore, molecular dynamics (MD) simulation was employed to calculate the binding energy, free volume fraction, solubility parameter, and mechanical properties of the composite system to explore the interfacial enhancement mechanism. The combined results of the experiments and MD simulation indicated that g‐BN exhibits strong interfacial interactions with the NR matrix, significantly improving the mechanical properties and thermal conductivity of the composites. This work provides a method to improve the compatibility of BN within the NR matrix, offering insight for the preparation of TIMs with high thermal conductivity for applications in electronic packaging devices. Highlights Boron nitride surface hyperbranched modification. Natural rubber composites with high thermal conductivity and mechanical properties. Interface enhancement mechanism was investigated by molecular dynamics simulation.