Record‐High Latent Heat, Ultra‐Fast Relaxation and Closed‐Loop Recycling Double‐Brush Polymer Networks for Self‐Adaptive Thermal Interface Management

In the era of artificial intelligence (AI)-driven high-performance computing, phase change materials (PCMs) are critical for high-flux thermal management. PCMs are evolving toward high enthalpy, low interfacial thermal resistance (ITR), and high reliability. Herein, we design double-brush phase-change polymer (PVBS-TMC_n) crosslinked by B─O─B and Si─O─B dynamic bonds, characterized by the ultra-fast relaxation time of 0.8 s under 80°C and closed-loop cycling. This architecture enhances the content of phase-change units for elevated theoretical enthalpy, while inherent multiple dynamic bonds and ultra-low entanglement minimize enthalpy loss, resulting in a record enthalpy of 240.7 J·g^-1. Furthermore, a composite of flexibility PVBS-TMC_14/24 and graphene foam films (PVBS-TMC/GF) is fabricated as thermal interface materials using a stacking-cutting strategy, which self-adaptively modulates low-ITR in response to temperature, owing to phase transition properties, ultra-low modulus, and adaptive filling capability of dynamic polymer matrix. PVBS-TMC/GF significantly generates better thermal management efficiency compared to commercial products. The topology design of double-brush polymer dynamic networks and interfacial contact mechanisms provide fundamental insights for developing phase-change adaptive materials and advancing thermal management.