High-Yield-Stress Particle-Stabilized Emulsion for Form-Factor-Free Thermal Pastes with High Thermal Conductivity, Stability, and Recyclability

Thermal pastes, thermally conductive fillers dispersed in liquid matrices, are widely used as thermal interface materials (TIMs). TIMs transfer heat generated from electronics to the surroundings, ensuring optimal operating temperatures. Thus, it is crucial to obtain high thermal conductivity (TC) by forming a continuous heat-conduction pathway through interconnected filler-networks within the TIM. Therefore, for paste-type TIMs with spherical fillers, high TC can only be realized at sufficiently high filler loadings (>60 vol%). However, the pastes bearing such high filler loadings are thick, stiff, and less applicable. To these ends, particle-stabilized emulsions composed of immiscible liquids (silicone oil and glycerol) and spherical alumina are utilized as thermal pastes. Owing to this structure, the resulting form-factor-free thermal paste exhibits higher TC and stability than a simple mixture consisting of alumina and a single-liquid-matrix (either silicone oil or glycerol). Furthermore, the high applicability of the emulsion-type pastes enables syringe extrusion, 3D printing, multiple cycles of reprocessing/molding, and eco-friendly recycling.