Microencapsulation of cholesteric liquid crystals (CLCs) toward flexible photonic applications

Cholesteric liquid crystals (CLCs) exhibit a photonic stop band due to their helical structure; a periodic modulation of ordinary and extraordinary refractive indices along the helical axis yields one-dimensional photonic band gap (PBG). And the unique optical properties of CLCs, such reflecting circularly polarized component of light, can be easily controlled by the concentration of chiral dopant with helical twisting power. However, the fluidity severely limits the ease of processing and structural stability, thereby restricting their flexible applications. One way to overcome the limitations is to encapsulate CLCs in microcontainers; microcapsules can be easily processed and reconfigured to construct photonic devices. In addition, CLCs confined in spherical microcapsule possess spherical symmetry, thereby providing rotationindependent optical properties. Here we have introduced several methods for CLC microencapsulation including interfacial polymerization, complex coacervation, and microfluidic system. And the optical properties of CLCs encapsulated in various polymer systems are investigated according to the temperature, concentration of chiral dopants and encapsulation methods.