Structural Color Elastomer Based on Two Different Mechanisms

Organisms capable of changing their body color generate color through a variety of mechanisms in response to environmental shifts and stimuli, resulting in color transformation. Inspired by these color changes, we can create sensors and optical materials that alter their color in response to various stimuli, such as mechanical and optical triggers.<br/>Using submicron-sized spherical silica particles as fillers and arranging them in a periodic structure within an elastomer can result in a silica composite elastomer with structural color changes. When this composite elastomer is stretched, its periodic structure changes, thereby affecting the structural color produced by the elastomer. According to Bragg's law, which takes into account Snell's equation, a blueshift occurs in silica composite elastomers when the distance between silica particles changes after stretching.<br/>Additionally, cholesteric liquid crystal elastomers (CLCEs) with helical structures can selectively reflect circularly polarized light, resulting in interesting optical effects. When the CLCEs are stretched, the change in pitch also produces a blue shift which is similar to silica the composite elastomer.However, the rate of change in blueshift is not synchronised between silica elastomers and CLCE due to different structural changes in blueshift caused by stretching. Moreover, the unique circular polarization of the CLCEs makes it possible to distinguish between the two different structural color change mechanisms.<br/>In this study, we report on a bioinspired composite elastomer that combines the helical structure of CLCEs with the periodic structure of the silica composite elastomer, enriching the chromatic effects of the composite elastomer and fabricating a cholesteric liquid crystal-silica (CLC-silica) composite elastomer with mechanochromism. This mechanochromism can be used to develop a unique strain sensor based on the CLC-silica composite elastomer, displaying complex color patterns upon stretching, with significant application potential in encryption, anti-counterfeiting, and other areas.