Gallium-Based Liquid Metal Amalgams: Transitional-State Metallic Mixtures (TransM2ixes) with Enhanced and Tunable Electrical, Thermal, and Mechanical Properties.

Metals are excellent choices for electrical- and thermal-current conducting. However, either the stiffness of solid metals or the fluidity of liquid metals could be troublesome when flexibility and formability are both desired. To address this problem, a reliable two-stage route to improve the functionalities of gallium-based liquid metals is proposed. A series of stable semiliquid/semisolid gallium-based liquid metal amalgams with well-controlled particle packing ratios, which we call TransM2ixes, are prepared and characterized. Through effectively packing the liquid metal with copper particles (which are found to turn into intermetallic compound, CuGa2, after dispersing), remarkable enhancements in electrical conductivity (6 × 106 S m-1, ∼80% increase) and thermal conductivity (50 W m-1 K-1, ∼100% increase) are obtained, making the TransM2ixes stand out from current conductive soft materials. The TransM2ixes also exhibit appealing semiliquid/semisolid mechanical behaviors such as excellent adhesion, tunable formability, and self-healing ability. As a class of highly conductive yet editable metallic mixtures, the TransM2ixes demonstrate potential applications in fields like printed and/or flexible electronics and thermal interface materials, as well as other circumstances where the flexibility and conductivity of interfaces and connections are crucial.