Breaking the Performance‐Reliability Trade‐OFF: Molecularly Anchored Topology for Efficient and Durable Interface Thermal Management

The relentless increase in advanced electronics’ power density makes thermal management a critical bottleneck, as the failure of thermal interface materials (TIMs) under cyclic thermal stress poses a fundamental reliability challenge. Conventional TIMs face an intrinsic trade‐off: compliant materials suffer from irreversible pump‐out, whereas stable crosslinked networks exhibit high interfacial thermal resistance due to poor conformability. Herein, we transcend this paradigm through a molecular design strategy leveraging reaction‐induced self‐assembly of a covalently anchored hybrid network. By transforming amino‐functionalized alumina (A–Al 2 O 3 ) into multifunctional “molecular rivets,” we construct a polyurea‐siloxane topology grafting rigid domains onto particle surfaces, thereby decoupling interfacial phonon transport from bulk viscoelasticity. This architecture simultaneously establishes continuous heat‐conduction pathways and immobilizes the filler‐matrix interface, while long, flexible siloxane spacers maintain grease‐like compliance even at 90 wt% filler loading. The optimized composite achieves high thermal conductivity (3.94 W·m − 1 ·K − 1 ) and ultralow contact resistance (0.78 K·cm 2 ·W − 1 ), alongside universal adhesion to metallic, ceramic, and polymeric substrates. Crucially, the covalent anchoring mechanism effectively suppresses pump‐out, enabling exceptional cycling stability (ΔT < 0.5°C) compared with the traditional silicone‐grease control. This work introduces a generalizable platform for durable thermal management via precision interfacial topology control, bridging the gap between high performance and long‐term reliability.