Microstructural Bridge Engineering of Boron Nitride/Silicone Rubber Composite With Enhanced Interface Heat Transfer

ABSTRACT The interfacial thermal resistance and phonon scattering at boron nitride (BN)/silicone rubber (SR) interfaces severely limit the thermal conductivity of BN/SR composites. To address this, this work proposes a microstructural bridge engineering strategy combining chemical interface modification and ice‐templated alignment. Hydroxylated BN nanosheets (BNNS‐OH) were first prepared via sucrose‐assisted ball milling, followed by silane coupling agent (KH570) grafting to introduce terminal double‐bond groups (BNNS‐DB). During SR curing, covalent bonds formed between BNNS‐DB and the matrix, reducing interfacial resistance. Vertical alignment via ice templating further optimized heat transfer pathways. The optimized composite achieved a remarkable thermal conductivity of 0.85 W/m K at 20 wt% filler loading, representing a 286% enhancement over pure SR and outperforming composites with unmodified BN by 23%. Infrared thermographic analysis demonstrated rapid thermal equilibration, reaching 64.4°C within 60 s under 80°C heating. This unique bridge strategy provides a scalable approach to design high‐efficiency thermal interface materials through synergistic interface and microstructure control.