Shape memory composites are fascinating materials with the ability to preserve deformed shapes that recover when triggered by certain external stimuli. Although elastomers are not inherently shape memory materials, the inclusion of phase-change materials within the elastomer can impart shape memory properties. When this filler changes the phase from liquid to solid, the effective modulus of the polymer increases significantly, enabling stiffness tuning. Using gallium, a metal with a low melting point (29.8 °C), it is possible to create elastomeric materials with metallic conductivity and shape memory properties. This concept has been used previously in core–shell (gallium-elastomer) fibers and foams, but here, we show that it can also be implemented in elastomeric films containing microchannels. Such microchannels are appealing because it is possible to control the geometry of the filler and create metallically conductive circuits. Stretching the solidified metal fractures the fillers; however, they can heal by body heat to restore conductivity. Such conductive, shape memory sheets with healable conductivity may find applications in stretchable electronics and soft robotics.

A bifunctional electrocatalyst based on heteroatoms doped VS2 was developed for electrocatalytic water splitting.

This work demonstrates a facile way to fabricate ultrastretchable thermo‐ and mechanochromic fiber with healable metallic conductivity. Thermochromic hollow elastic fiber is prepared by using silicone composite with thermochromic pigment. Once the fiber forms, gallium‐based liquid metal is injected into the fiber. The composite fiber with liquid metal core shows uniform color change along the fiber by applying Joule heating through the liquid metal wire. The fiber with multiple thermochromic pigment locally distributed along the fiber shows serial color change by increased current. The healable conductivity of the metal core is demonstrated by restoring electrical conductivity near room temperature. When it is in a solid state, the wire can fracture during deformation, thus the wire loses conductivity. However, upon body heating, the wire can rewire, because of the low melting point of the metal (gallium, 29.8 °C). This healing ability of the metal core can allow the fiber to have healable thermochromic behavior. Stretching a liquid metal wire can change the geometry of the wires, resulting in a color change because of increased resistance while Joule heating is applied. This thermo‐ and mechanochromic fiber with liquid metal core would find use in wearable and conformal electronics, electronic textiles, and soft robotics.

Stretchable and soft piezoresistive composites are appealing for application to tactile sensors, artificial skin, and wearable electronics. The ability of the composites to deform the geometries when they are strained can allow the electrical behavior of the composites to be manipulated. Although rigid metal and semiconductor inclusions have been utilized to create piezoresistive composites, they limit the degree of mechanical deformation. Here, liquid metal (gallium, melting point ≈ 29.7 °C) inclusion into elastomeric foam substrate with 3D open cell morphologies is utilized. Gallium is a fluidic conductor, thus it is possible to infiltrate the liquid metal into the 3D interconnected pore, resulting in soft, stretchable, and shape reconfigurable conductive composites that can change shape and function in response to external stimuli. Applying strain can enable deformation of the liquid metal, generating changes of electrical resistance. Interestingly, it is found that this piezoresistivity of the composite can be positively and negatively manipulated by adjusting the geometries of the liquid metal in the foam. Furthermore, the liquid metal in the elastomeric foam can be reversibly actuated by applying compressive force, resulting in manipulation of the restorative electrical activity of the composites.

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