Photonic Spring‐Like Shell Templated from Cholesteric Liquid Crystal Prepared by Microfluidics

Solid‐state photonic shells are prepared with a reactive cholesteric liquid crystal (CLC) mixture that consists of a reactive mesogen mixture and the nonreactive chiral dopant. The shells are prepared using a microfluidic glass‐capillary chip, followed by UV‐curing and extraction of the chiral dopant. CLC shells with relatively uniform thickness are produced by density matching and annealing. The produced solid‐state CLC (CLC_solid) shells show a good reversible swelling/shrinkage behavior that is dependent on the solvent quality and temperature. The swelling or shrinkage simultaneously induces a color change in the reflection point at the center and in the cross‐communication dots. Encapsulation and release from the CLC_solid‐shell cores are successfully tested with Rhodamine 6G by controlling the solvent quality and temperature. Nanosized Fe₃O₄ particles encapsulated in the core give the CLC_solid shells mobility, and are assembled at the desired location using a magnet. The color changes caused by external stimuli can be applied to new types of small hollow sensors that will respond to changes in temperature, and solvent quality. The shells can be used, for example, as a chemical container that can be triggered by temperature to release for a delayed reaction, or in a security patch controlled by tuneable multicolored patterns.