Controlled Transformation of Liquid Metal Microspheres in Aqueous Solution Triggered by Growth of GaOOH

Abstract

Liquid metals (LMs) are playing an increasingly important role in the fields of flexible devices, electronics, and thermal management due to their low melting point and excellent thermal and electrical conductivity, and the transformation of LMs in deionized water has recently received much attention. In this paper, we investigate the transformation process of EGaIn microspheres in deionized water and propose a two-step process of microspherical transformation, whereby the microspheres are first deformed into a spindle shape and then into lamellar nanorods. It is also shown that the growth of GaOOH crystals drives the transformation. Based on this result, EGaIn microspheres with controllable transformation could be prepared, such as spindle or lamellar rod shapes, extending the application area of LMs.

Transportable, Endurable, and Recoverable Liquid Metal Powders with Mechanical Sintering Conductivity for Flexible Electronics and Electromagnetic Interference Shielding

“…Under heating or long time storage circumstance, EGaIn micro/nanodroplets produced by ultrasonication in water (Figure S10A−C) or organic solvents had been proved that these were tended to transform into nonconductive GaOOH lamellae or nanorods because of the chemical reaction of Ga, water, and oxygen, resulting in the low chemical stability. 18 In addition, EGaIn coating produced from micro/nanodroplets by filtration tended to yield cracks on substrates, which would be fatal in electronic applications. 39 Surprisingly, LMPs could be stored in water for more than one month and still formed stable LMPs after being removed from the water, thus generating conductive routes by mechanical sintering (Figure S10D).…”

“…However, these LMs' nanodroplets still lack enough oxidation resistance due to the active metal atoms on their dynamic surfaces, resulting in chemical instability in various solvents. 18 It has been demonstrated that LMs can be wetted on high surface energy substrates (e.g., Au, 23 Ag, 24,25 and Cu 26 ) and form metallic bonds that cling securely to the substrate. In addition, the hydrogen bonds between gallium oxide layer and polymethacrylate glue are vital for achieving outstanding adhesion on substrates.…”

“…Generally, EGaIn micro/nanodroplets can be fabricated by sonication, microfluidic, nebulization, and shearing, which can be utilized in patterning on various substrates (e.g., polyethylene terephthalate (PET), cellulose, glass, and elastomers). Nanometerization of LMs in organic fluids or aqueous solutions can promote the deposition of LMs’ droplets onto substrates and later sintering to recover its conductivity. − Usually, EGaIn micro/nanodroplets were coated with shells (monolayer, biological macromolecule, or polymers) via chemical bonds, coordination, or polymerization to enhance the colloidal stability. However, these LMs’ nanodroplets still lack enough oxidation resistance due to the active metal atoms on their dynamic surfaces, resulting in chemical instability in various solvents …”

Self-healing liquid metal hydrogel for human–computer interaction and infrared camouflage

“…Gallium indium alloy (EGaIn), as one kind of liquid metal (LM) that has a melting point close to or below room temperature, [20][21][22] has been widely used in electronic devices, thermal management, soft robots, and biological devices due to its excellent electrical and thermal conductivity, 23,24 low melting point (15.6 1C), 25 and non-toxicity. 26 In addition, EGaIn can be prepared into EGaIn microspheres by ultrasonic dispersion, 27,28 which can be used as nanofillers. EGaIn microsphere fillers are different from other rigid nanofillers because they can adapt to the deformation of the polymer matrix, thus effectively toughening the polymer.…”

Rapidly responsive liquid metal/polyimide photothermal actuators designed based on the bilayer structure difference in coefficient of thermal expansion

“…However, since most of the photothermal fillers are inorganic rigid particles, which can have a large impact on the flexibility of the substrate of the actuator and can seriously decrease the response speed of the photoactuator. In contrast, a liquid metal (LM), as an emerging flexible material, combines the fluidity of liquid 13 with the electrical conductivity 14 and thermal conductivity 15 of metal. What's more, similar to gold nanocrystals 16 and silver nanocrystals, 17 LM particles have photothermal effects in the near-infrared (NIR) laser.…”