Liquid Metal Composites

Abstract

Liquid metal (LM) with high electrical conductivity, thermal conductivity, excellent biocompatibility, and extraordinary fluidity has emerged as a promising class of functional materials. However, such materials still encounter many practical challenges due to the rather limited forms available so far. As a promising remedy, LM composites in synergy with other materials would open tremendous opportunities for fundamental research or practical applications. This is because controllable integration of base LM with functional materials (e.g., metal nanoparticles, polymers, and drug molecules) would significantly tune the intrinsic properties of LM as desired, enabling it to offer further major potential in tackling various sectors' challenging issues, including thermal management, biomedicine, chemical catalysis, flexible electronics, and soft robots. Here, we systematically summarize and review the fundamental progress in pursuing LM composites. The basic composite strategies are outlined in three categories: LM composites with core-shell structure, LM-polymer composites, and LM-particle composites. The effectiveness of the composite strategy is illustrated via the typical applications of LM composites in representative fields. The challenges and perspectives in developing LM composites are also identified and interpreted to better guide future research. It is expected that the coming LM era will witness a new world of fruitful composites thereby discovered or invented.

General Programmable Growth of Hybrid Core–Shell Nanostructures with Liquid Metal Nanodroplets

“…As a commonly used route for the preparation of water‐based emulsions, facile probe sonication was applied here to introduce cavitation in the solution and local extremes of pressure on the LM. [ 8 ] The oscillating shear force can easily fracture the initial oxidation layer that stabilizes the Ga‐based LM bulk. Small LM droplets successively separate from the bulk matrix in a spherical shape, due to the high surface energy of the freshly exposed oxide‐free LM surface.…”

Interfacial Engineering of Room Temperature Liquid Metals

“…The rheological characteristics of RTLM make it attractive enough in the areas of thermal control, [ 171 ] flexible batteries, [ 172 ] and self‐healing composites. [ 106,151,172a ] As a fluid medium, the corrosion effect of objects in contact with RTLM will largely determine applications of materials utilized. The corrosion of gallium‐based liquid metal to metallic iron and copper is as mentioned above.…”

“…The wetting paradigm of the solid-liquid interface is of great significance for revealing the correspondence between properties of interfacial products and wetting behaviors, which would provide a scientific basis for engineering potential applications, such as welding, [19,104] electronic device packaging, [3,105] chemical reaction in solution, [22,65] and fabrications of composite materials. [106][107][108] The wetting phenomenon of the solid-liquid metal interface could be segmented into physical wetting (inert wetting) and reactive wetting (chemical wetting), according to whether chemical reactions occur and new substances form at the interface. In addition to general contact angle for visualization of wettability, [109,110] the adhesion work that describes the mutual attraction of liquid molecules and solid molecules, is characterized to calculate wettability theoretically.…”

Pervasive liquid metal printed electronics: From concept incubation to industry

“…Currently, successfully doped metal particles have included Cu, Ag ( Tang et al., 2017 ), Fe ( Cao et al., 2020 ; Carle et al., 2017 ; Hu et al., 2019 ), Ni ( Chang et al., 2018 ; Guo et al., 2018c ), Mg ( Wang et al., 2018c ), W ( Kong et al., 2019 ), etc. Further, based on more generalized liquid metal composite strategy ( Chen et al., 2020 ), the liquid metal dispersed into micro-nano droplets can form liquid metal-polymer composites with the polymer ( Chechetka et al., 2017 ; Fassler and Majidi, 2015 ; Krisnadi et al., 2020 ; Li et al., 2018 , 2020 ; Peng et al., 2019 ; Tang et al., 2018 ; Wang et al., 2018b ), and the resulting ink can be flexibly applied to different substrates ( Figure 2 B). But because of the dispersed liquid metal droplets, special treatments to make them conductive are usually necessary, such as laser ( Deng and Cheng, 2019 ; Liu et al., 2018a ), low temperature ( Chen et al., 2019 ; Wang et al., 2019 ), mechanical pressure ( Boley et al., 2015 ; Zhang et al., 2019a ), evaporation ( Li et al., 2019b ), in situ reduction of silver shell ( Zheng et al., 2020 ), and stretch ( Thrasher et al., 2019 ; Xin et al, 2019 ).…”