A Thermochromic Hydrogel for Camouflage and Soft Display

Recently, hydrogels with coloration have attracted researchers from various fields, such as camouflage, anti‐counterfeiting, and soft display. However, existing thermochromic hydrogels are limited by their weak color display performance and insufficient sensitivity. Here proposed is a new kind of thermochromic hydrogel which possesses bright colors, fast response time, and reliable results across a long lifespan. This hydrogel is prepared by embedding temperature‐responsive microcapsules containing three components: color developing agent, leuco agent, and solvent. The critical temperature for color changing of the microcapsule is determined by the phase transfer temperature of the solvent. The macroscopic coloration and discoloration of this hydrogel are fast. Soft display and camouflage are proposed for the practical applications in which the thermochromic hydrogel acts as the chameleon phase and the electrothermal filaments as the driving phase. The thermochromic hydrogel can be readily integrated into heat‐sensing devices and smart clothes. A thermochromic hydrogel by combining thermochromic capsule powders and PAAm hydrogels as well as a series of relevant electro‐actuated devices are proposed. The displayed colors are consistent and the discoloration only depends on temperature. In addition, the discoloration pattern could be designed and manufactured for applications in camouflage and soft displays.