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

Abstract

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.