LAUSR

Effective heat dissipation is essential for optimizing the performance and extending the service life of electronic devices. However, developing thermal interface materials (TIMs) that integrate excellent stretchability, self‐adhesiveness, and high thermal conductivity still represents a significant challenge. Balancing the interfacial heat transfer with the mechanical force transfer is particularly a key barrier for TIMs. In this work, we strategically design a polymer composite by incorporating Al2O3 filler in a synthetic polyphenol‐rich flexible elastomer (PRFE). The applied PRFE was synthesized through a stepwise polymerization process, enabling the integration of flexible chain segments and rigid polyphenol structures. The PRFE composite exhibits an excellent thermal conductivity of 5.4 W/m K and holds low thermal resistance (~0.29 K cm2/W) under high‐loading states. This can be attributed to the synergy between the polydimethylsiloxane (PDMS) flexible chain segments and the polyphenol structure, which combines to form a well‐developed thermal conductivity pathway with efficient interfacial contact. Due to the well‐designed macromolecular structure, the obtained composite demonstrates advanced mechanical properties, including low modulus, excellent adhesive performance, and notable toughness simultaneously. This work provides a novel approach for fabricating advanced thermally conductive composites, along with a flexible and practical strategy for designing TIMs.