Low-Modulus Thermal Interface Materials with Bicontinuous Heat-Conduction Pathways Enabled by Liquid Metal and Graphene Films

Developing thermal interface materials (TIMs) with high thermal conductivity (k) and good mechanical compliance is critical for thermal management of high-power electronics. However, conventional polymer-based TIMs usually suffer from low intrinsic k, while the incorporation of highly conductive fillers often leads to increased stiffness and reduced compressibility. Herein, we developed a composite TIM by integrating polybutadiene-encapsulated liquid metal (LM@PB) with vertically aligned graphene films (GFs), termed LM@PB/GF. A uniform and stable LM@PB slurry was prepared via solvent-assisted ultrasonic dispersion, and silane modification was used to strengthen the interfacial bonding between GFs and LM@PB. Through a stacking–cutting method, bicontinuous heat-conduction pathways were constructed for efficient through-plane heat transport. Benefiting from this dual heat-conduction network and the softness of LM@PB, LM@PB/GF achieved a favorable balance between thermal performance and mechanical compliance, delivering a high through-plane k of 151.02 W m–1 K–1 together with a low compressive modulus of 2.09 MPa (25–40% strain). In practical heat-dissipation tests, LM@PB/GF outperformed commercial TIM Laird T-flex 700 and maintained stable performance under cyclic heating–cooling cycling. This work provides an effective strategy for achieving high thermal conductivity and low modulus in GF-based TIMs, showing great promise for advanced thermal management in next-generation electronic devices.