A double inclusion model for liquid metal polymer composites

gallium-based LM alloys such as EGaIn (eutectic gallium-indium) or galinstan (eutectic gallium-indium-tin) are typically selected as the liquid filler due to the combination of high electrical and thermal conductivity, low viscosity, and nontoxic characteristics. [4][5][6][7] By dispersing LM inclusions into elastomers, functional properties-including thermal conductivity, [8][9][10][11][12][13][14][15] dielectric constant, [16][17][18][19][20][21] and electrical conductivity, [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] -can be improved with negligible changes in stiffness and extensibility of the host elastomer, even at high loading. LM embedded composites exhibit a unique combination of functional properties, low stiffness, and high strain limit that overcomes fundamental limitations of soft and deformable materials and offers great promise for emerging applications in soft robotics and wearable computing that require highly functional and elastically deformable materials. Despite the improved properties, both the density of Ga-based LMs (EGaIn: 6.25 g cm −3 ; galinstan: 6.44 g cm −3 ) and typically high loading (⩾85 wt%, or ⩾50 vol%) required to achieve the desired functional properties contribute to the high density of LM embedded composites, which can be problematic for largearea and weight-sensitive applications.Recently, researchers have shown that the properties of Gabased LMs can be enhanced through the addition of solid particles. Several LM mixtures have been studied to improve the thermo-mechanical properties [10,11,[40][41][42][43][44][45][46][47][48][49] , rheology and consistency, [50][51][52][53][54][55][56][57][58] and density [58,59] of LM. This has resulted in LM mixtures with high thermal conductivity >100 W m −1 K −1 , a fourfold increase as compared to pure LM, [43,44] LM pastes that can be easily spread on a surface, [40] and LM mixtures that can float on water. [59] However, LM mixtures that include metallic particles with fcc crystal structures, such as copper (Cu), silver (Ag), iron (Fe with fcc crystal structure), and nickel (Ni), tend to spontaneously react with LM and form intermetallics that solidify at low loading. [10] For LM mixtures with particles that do not form intermetallic species, the rheology and consistency of the mixtures are controlled by the fraction of solid particles that are added to the mixture, resulting in a transition from a liquid to paste-like rheology (⩽50% by volume) or liquid to powder at higher volume loading (>50%). [40,44,52,53,59] The viscosity of the Lightweight and elastically deformable soft materials that are thermally conductive are critical for emerging applications in wearable computing, soft robotics, and thermoregulatory garments. To overcome the fundamental heat transport limitations in soft materials, room temperature liquid metal (LM) has been dispersed in elastomer that results in soft and deformable materials with unprecedented thermal conductivity. However, the high density of LMs (>6 g cm −3 ) and the typical...

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confidence: 99%

Lightweight, Thermally Conductive Liquid Metal Elastomer Composite with Independently Controllable Thermal Conductivity and Density

Krings

Zhang

Sarin

et al. 2021

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“…This can lead to increased stiffness or mechanical cloaking depending on composite parameters and the size of LM inclusions. In a recent study, a double inclusion micromechanics model was introduced to predict the effective elastic properties of LMPCs with core‐shell LM inclusions 76 . This modeling result confirmed the important role of the oxide interface in the elastic response of LMPCs with different matrix materials.…”

Section: Structural Propertiesmentioning

confidence: 66%

Multifunctional liquid metal polymer composites

Guymon

Malakooti

2022

Journal of Polymer Science

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Liquid metal polymer composites are an emerging class of functional materials with potentially transformative impacts in wearable electronics, soft robotics, and human-computer interactions. By employing different processing methods, room temperature liquid metal inclusions can be embedded in insulating polymers like elastomers to incorporate functional properties of metals while the matrix remains soft and stretchable. These solid-liquid composites offer an interesting, yet complex multifunctional material system. In this review, we present an exclusive overview of the synthesis methods, structural and functional properties, and applications of gallium-based liquid metal polymer composites. Common methods to control the size of liquid metal inclusions and their interaction in polymers are discussed. Moreover, the effect of liquid metal microstructures on the overall properties of the composites is summarized. We also highlight the new trends in terms of material composition, printing process, and novel applications of liquid metal polymer composites in intelligent systems.

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“…Alternatively, a soft matrix can incorporate a liquid filler that imparts the desired properties without mechanical mismatch as long as the interface of the liquid filler is controlled [139,140]. By studying composites with liquid fillers, new understandings of the effects of surface tension on mechanical properties led to the development of new inclusion theories [140,141]. The interphase, which refers to the structure that connects the matrix and filler beyond the absorption layer and is important for fiber-reinforced composites, is also important to understand for functional composites with both liquid and solid inclusions.…”

Section: Interfaces Of Disparate Materialsmentioning

confidence: 99%

Composites of functional polymers: Toward physical intelligence using flexible and soft materials

Ford

Ohm

Chin

et al. 2021

Journal of Materials Research

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Materials that can assist with perception and responsivity of an engineered machine are said to promote physical intelligence. Physical intelligence may be important for flexible and soft materials that will be used in applications like soft robotics, wearable computers, and healthcare. These applications require stimuli responsivity, sensing, and actuation that allow a machine to perceive and react to its environment. The development of materials that exhibit some form of physical intelligence has relied on functional polymers and composites that contain these polymers. This review will focus on composites of functional polymers that display physical intelligence by assisting with perception, responsivity, or by off-loading computation. Composites of liquid crystal elastomers, shape-memory polymers, hydrogels, self-healing materials, and transient materials and their functionalities are examined with a viewpoint that considers physical intelligence. Graphic Abstract

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A double inclusion model for liquid metal polymer composites

Cited by 41 publications

References 46 publications

Lightweight, Thermally Conductive Liquid Metal Elastomer Composite with Independently Controllable Thermal Conductivity and Density

Lightweight, Thermally Conductive Liquid Metal Elastomer Composite with Independently Controllable Thermal Conductivity and Density

Multifunctional liquid metal polymer composites

Composites of functional polymers: Toward physical intelligence using flexible and soft materials

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