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

Abstract

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 (CLCsolid) 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 CLCsolid‐shell cores are successfully tested with Rhodamine 6G by controlling the solvent quality and temperature. Nanosized Fe3O4 particles encapsulated in the core give the CLCsolid 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.

Micrometer‐Scale Porous Buckling Shell Actuators Based on Liquid Crystal Networks

“…Yet, the delicate nature of the liquid–liquid interfaces bounding regular LC shells represents a drawback, limiting their lifetime and preventing their removal from the continuous liquid phase. To circumvent this limitation, some reports have included mesogens with polymerizable end groups, either for polymer stabilization of a shell that remains largely fluid or for turning the shell into a polymeric solid or rubber . So far, only one study was presented with LCN shell actuators .…”

Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

“…Past decades are characterized by the explosive development of technologies based on optoelectronics and photonics . The modern elemental base of these technologies includes refractive, diffraction and optical fiber components.…”

Magnetic Nanoparticle-Assisted Tunable Optical Patterns from Spherical Cholesteric Liquid Crystal Bragg Reflectors

“…The employ of photoresponsive molecular switches enabled a wide tuning range of the pitch length of CLCs and hence of the highly selective CP reflection wavelength emanating from paired spherical CLC Bragg reflectors [ 16 ]. In addition, it was reported that the transition from droplets to shells gave rise to sharp patterns and sustained excellent optical quality even after polymerization [ 19 , 20 ].…”

“…Also, it is difficult to manipulate each individual spherical CLC Bragg reflector and organize relatively small amounts of them into various separated geometric figures independently. Very recently, by means of magnetic manipulation strategies, the noncontact transport of CLC microshells was successfully achieved with microfluidic devices [ 13 , 19 ]. Chen et al fabricated dye-doped CLC microshells encapsulated with water-dispersible Fe 3 O 4 nanoparticles for a magnetically-transportable tunable microlaser [ 13 ].…”

“…Chen et al fabricated dye-doped CLC microshells encapsulated with water-dispersible Fe 3 O 4 nanoparticles for a magnetically-transportable tunable microlaser [ 13 ]. Park et al also demonstrated the capability of solidified CLC microshells with Fe 3 O 4 nanoparticles as new types of location-adjustable sensors for the detection of temperature changes, solvent quality, and humidity [ 19 ].…”