Reversible On–Off of Chirality and Anisotropy in Patterned Coexistence of Achiral‐Anisotropic and Chiral‐Isotropic Soft Materials

Abstract

Achieving a coexistence of two or multiple phases of soft matters via a delicate trade‐off of free energy and long‐range order with one another has been inspiring abundant interest on fundamental sciences and engineering. In this work, a stable coexistence of the optically achiral‐anisotropic liquid crystalline nematic phase and the optically chiral‐isotropic liquid crystalline blue phase is proposed and demonstrated, with their distribution tailored in a micro‐pattern by the developed localized micro‐regional polymer templating technique. Such a stable patterned coexistence of the two different phases with a distinct molecular arrangement, optical chirality, and anisotropy is achieved depending on a delicate matching of the elastic energy on the interface between liquid crystals and polymer networks. In contrast to the majority of soft coexistence systems, a specific dynamic and reversible on–off response of chirality and anisotropy is observed in such a system driven by an electric field. The structure of patterned coexistence system in the presence and absence of external stimulation is explored by microscopy and optical technique, and furthermore, the prospective photonic applications are demonstrated. This investigation indicates another category of functional soft material with fantastic adaptive characteristics for application in optics, electronics, interface physics, and chemistry.

Liquid Crystals: Versatile Self-Organized Smart Soft Materials

“…With the help of polymer templating, the micropatterns of nematic and blue phases have been developed, and their applications have been explored. 177 Bent-shaped hydrogen bonded assemblies containing azobenzene based mesomorphic groups have been used in the development of LC blue phases. 178 The blue phases are stable close to room temperature, and their Bragg reflection can be tuned with light irradiation.…”

“…Photonic application of such a conglomerate micropattern with 1D and 3D chiral soft structures has also been demonstrated. With the help of polymer templating, the micropatterns of nematic and blue phases have been developed, and their applications have been explored …”

High‐Resolution Erasable “Live” Patterns Based on Controllable Ink Diffusion on the 3D Blue‐Phase Liquid Crystal Networks

“…[7,11] Currently, the research on BPLCs mainly focused on broadening the temperature range [1,2,[13][14][15][16] of films, realizing the largedomain single crystals, [5,17] investigating the phase transition process [9,[18][19][20][21][22][23][24] and pursuing functional BPLCs for device applications. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] BPLCs, with the unitcell lattice spacing on the order of the wavelength of visible light, exhibit a selective reflection as a photonic crystals and present tuneable photonic stopband/structural coloration accompanied by exterior stimuli. Programmable color-changing BPLC pattern has attracted wide research attention owing to its promising applications in adaptive camouflage, concealing, protection, or display.…”

“…Various responsive patterns have been fabricated by introducing responsive materials into BPLC system, where the pattern can be modulated based on the distinct external field interaction, such as electricity, [7,11,12,27,28] light, [30,36,39] humidity, [26,34] temperature, [31] pressure, [32] magnetic field, [37] solvent, [40] etc. Typically, Li et al realized reversible switching between Blue phase II and chiral nematic phase based on achiral photoresponsive molecular switch, [29] and the well-defined micropattern was obtained by photomask technology. Zheng et al [31] realized micropatterning with erasable/written on-demand by light.…”

3D Chiral Photonic Nanostructures Based on Blue‐Phase Liquid Crystals

“…[ 56–63 ] In this regard, 1D photonic superstructures based on cholesteric liquid crystals (CLCs) have been extensively investigated and widely applied in reflective displays, tunable lasers, and other advanced chiral photonic devices. [ 64–79 ] Blue‐phase liquid crystals (BPLCs) with cubic lattice nanostructures have recently entered the research limelight due to their ability to self‐organize into 3D chiral photonic crystals that can manipulate light or the flow of photons in all the three dimensions. [ 80–85 ] Herein, we present a comprehensive review of the state‐of‐the‐art in 3D chiral photonic nanostructures based on BPLCs and their potential applications.…”