Mobile‐Chain‐Assisted Flow Alignment and Interfacial Adaptation Enable Elastomeric Thermal Interface Materials with High through‐Plane Thermal Conductivity and Low Contact Thermal Resistance

ABSTRACT The performance of conventional chemically cross‐linked elastomeric thermal interface materials (E‐TIMs) is fundamentally limited by the intrinsic trade‐off between through‐plane thermal conductivity and interfacial contact resistance. In this work, we propose a mobile‐chain‐assisted flow‐alignment and interfacial‐adaptation strategy by introducing free high‐molecular‐weight hydroxyl‐functional silicone chains into a silicone cross‐linked network. The mobile hydroxyl‐functional chains act as a dual regulator: they facilitate flow‐field‐induced vertical alignment of carbon fibers during extrusion and endow the elastomer matrix with enhanced interfacial wettability, chain mobility, and adaptive conformability. Consequently, the fabricated V‐cSi/fSi‐OH/CF TIM achieves a remarkable through‐plane thermal conductivity of 54.7 W·m −1 ·K −1 . More importantly, the mobile hydroxyl‐functional chains enable near‐conformal interfacial adaptation with heat‐sink surfaces even under a low pressure (1 psi), yielding a calculated contact thermal resistance of 11.2 K·mm 2 ·W −1 (an 84% reduction compared to conventional cross‐linked counterparts). This mobile‐chain‐assisted design strategy provides a generalizable route for developing elastomeric TIMs that combine efficient through‐plane heat conduction with low‐resistance interfacial heat transfer.