Materials with a temperature‐controlled reversible electrical transition between insulator and conductor are attracting huge attention due to their promising applications in many fields. However, most of them are intrinsically rigid and require complicated fabrication processes. Here, a highly stretchable (680% strain) liquid metal polymer composite as a reversible transitional insulator and conductor (TIC), which is accompanied with huge resistivity changes (more than 4 × 109 times) reversibly through a tuning temperature in a few seconds is introduced. When frozen, the insulated TIC becomes conductive and recovers after warming. Both the phase change of the liquid metal droplets and the rigidity change of the polymer contribute directly to transition between insulator and conductor. A simplified model is established to predict the expansion and connection of liquid metal droplets. Along with high stretchability, straightforward fabrication methods, rapid triggering time, large switching ratio, good repeatability, the TIC offers tremendous possibilities for numerous applications, like stretchable switches, semiconductors, temperature sensors, and resistive random‐access memory. Accordingly, a system that can display numbers and letters via converting alternative TIC temperature to a binary signal on a computer is conceived and demonstrated. The present discovery suggests a general strategy for fabricating and stimulating a stretchable transitional insulator and conductor based on liquid metal and allied polymers.

Gallium-based room-temperature liquid metals are becoming increasingly attractive and outstanding candidates for designing soft robots because of their remarkable electrical conductivity, superior flexibility, excellent stability, and low toxicity. However, the color of liquid metals is limited to shiny silver-white with high reflectivity, which is not helpful for camouflage, like that found in natural soft animals such as cephalopods. Herein, a biomimetic chromatic liquid-metal soft robot with tunable structural colors is reported. Colors ranging from white to gold and black appear on the surface of liquid metal when placed on a graphite substrate and mixed with Al foil in an electrolyte solution. A stable liquid-metal functional material with a rainbow-like appearance is realized under the regulation of an electric field. Further composition and structure characterization reveals that it is a nanoscale Ga2O3 film that displays the multicolor characteristic. The nanostructural film indicates that light scattering of Ga2O3 occurs when the liquid metal is on the graphite surface, and thin-film interference triggers iridescence when the liquid metals are subjected to electrolysis, respectively. These results provide a route to create kaleidoscopic and colorful liquid metals, which are expected to have diverse applications, especially in reinforcing soft robot design with intelligent camouflage function.

Directly contrasting ultrafast excited-state dynamics in the gas and liquid phases is crucial to understanding the influence of complex environments. Previous studies have often relied on different spectroscopic observables, rendering direct comparisons challenging. Here, we apply extreme-ultraviolet (XUV) time-resolved photoelectron spectroscopy (TRPES) to both gaseous and liquid cis-stilbene, revealing the coupled electronic and nuclear dynamics that underlie its isomerisation. Our measurements track the excited-state wave packets from excitation along the complete reaction path to the final products. We observe coherent excited-state vibrational dynamics in both phases of matter that persist to final products, enabling the characterisation of the branching space of the S 1 -S 0 conical intersection. We observe a systematic lengthening of the relaxation time scales in the liquid phase and a red shift of the measured excited-state frequencies that is most pronounced for the complex reaction coordinate. These results characterise in detail the influence of the liquid environment on both electronic and structural dynamics during a complete photochemical transformation.