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This work reveals the intricate interplay between curvature, shell thickness, and anchoring asymmetry in governing structural transitions, dynamic behavior, and defect morphologies in highly chiral cholesteric liquid crystal shells. 

Blue phase (BP) liquid crystals represent a fascinating state of soft matter that showcases unique optical and electro-optical properties. Existing between chiral nematic and isotropic phases, BPs are characterized by a three-dimensional cubic lattice structure resulting in selective Bragg reflections of light and consequent vivid structural colors. However, the practical realization of these material systems is hampered by their narrow thermal stability and multi-domain crystalline nature. This feature article provides an overview of the efforts devoted to stabilizing these phases and creating monodomain structures. In particular, it delves into the complex relationship between geometrical confinement, induced curvature, and the structural stability and photonic features of BPs. Understanding the interaction of curved confinement and structural stability of BPs proves crucially important for the integration of these materials into flexible and miniaturized devices. By shedding light on these critical aspects, this feature review aims to highlight the significance of understanding the coupling effects of physical and mechanical forces on the structural stability of these systems, which can pave the way for the development of efficient and practical devices based on BP liquid crystals. 

When viewed with a cross-polarized optical microscope (POM), liquid crystals display interference colors and complex patterns that depend on the material's microscopic orientation. That orientation can be manipulated by application of external fields, which provides the basis for applications in optical display and sensing technologies. The color patterns themselves have a high information content. Traditionally, however, calculations of the optical appearance of liquid crystals have been performed by assuming that a single-wavelength light source is employed, and reported in a monochromatic scale. In this work, the original Jones matrix method is extended to calculate the colored images that arise when a liquid crystal is exposed to a multi-wavelength source. By accounting for the material properties, the visible light spectrum and the CIE color matching functions, we demonstrate that the proposed approach produces colored POM images that are in quantitative agreement with experimental data. Results are presented for a variety of systems, including radial, bipolar, and cholesteric droplets, where results of simulations are compared to experimental microscopy images. The effects of droplet size, topological defect structure, and droplet orientation are examined systematically. The technique introduced here generates images that can be directly compared to experiments, thereby facilitating machine learning efforts aimed at interpreting LC microscopy images, and paving the way for the inverse design of materials capable of producing specific internal microstructures in response to external stimuli. 

Designing simple, sensitive, fast, and inexpensive readout devices to detect biological molecules and biomarkers is crucial for early diagnosis and treatments. Here, we have studied the interaction of the chiral liquid crystal (CLC) and biomolecules at the liquid crystal (LC)-droplet interface. CLC droplets with high and low chirality were prepared using a microfluidic device. We explored the reconfiguration of the CLC molecules confined in droplets in the presence of 1,2-diauroyl-sn-glycero3-phosphatidylcholine (DLPC) phospholipid. Cross-polarized optical microscopy and spectrometry techniques were employed to monitor the effect of droplet size and DLPC concentration on the structural reorganization of the CLC molecules. Our results showed that in the presence of DLPC, the chiral LC droplets transition from planar to homeotropic ordering through a multistage molecular reorientation. However, this reconfiguration process in the low-chirality droplets happened three times faster than in high-chirality ones. Applying spectrometry and image analysis, we found that the change in the chiral droplets’ Bragg reflection can be correlated with the CLC–DLPC interactions. 

Abstract Blue phases (BPs), formed through the self‐assembly of chiral liquid crystal molecules into 3D nanolattices with cubic symmetries, exhibit dynamic photonic bandgaps in the visible spectrum, offering transformative opportunities for advanced optical circuits, sensing and communication technologies. However, their thermal stability is restricted to a narrow temperature range (0.5–1.0 K), limiting practical applications. Polymer stabilization of bulk BPs has extended thermal stability but often compromises the dynamic behavior essential for fast‐response functionalities. Here, experimental and computational approaches are integrated to investigate the effect of curvature and interfacial interactions on BP polymer stabilization. It is demonstrated that photo‐polymerization of reactive monomers within BP microdroplets produces polymer shells, a few hundred nanometers thick, featuring BPs disclination network nano‐architecture. This nano‐architected shell provides surface topology and anchoring conditions to direct BP nucleation and growth, with the degree of curvature dictating the stabilized BP lattice structure within microdroplets. Remarkably, while enhancing thermal stability across a broad temperature range, this polymer shell enables reconfigurable crystal‐to‐crystal transformations in stabilized BP droplets. This work introduces a novel approach to tailoring BP properties by leveraging curvature, confinement, and interfacial interactions to create thermally stable, reconfigurable photonic crystals, paving the way for adaptive sensors and next‐generation fast‐response optical devices. 

Liquid crystals are important components of optical technologies. Cuboidal crystals consisting of chiral liquid crystals−the so-called blue phases (BPs),are of particular interest due to their crystalline structures and fast response times, but it is critical that control be gained over their phase behavior as well as the underlying dislocations and grain boundaries that arise in such systems. Blue phases exhibit cubic crystalline symmetries with lattice parameters in the 100 nm range and a network of disclination lines that can be polymerized to widen the range of temperatures over which they occur. Here, we introduce the concept of strain-controlled polymerization of BPs under confinement, which enables formation of strain-correlated stabilized morphologies that, under some circumstances, can adopt perfect single-crystal monodomain structures and undergo reversible crystal-to-crystal transformations, even if their disclination lines are polymerized. We have used super-resolution laser confocal microscopy to reveal the periodic structure and the lattice planes of the strain and polymerization stabilized BPs in 3D real space. Our experimental observations are supported and interpreted by relying on theory and computational simulations in terms of a free energy functional for a tensorial order parameter. Simulations are used to determine the orientation of the lattice planes unambiguously.The findings presented her eoffer opportunities for engineering optical devices based on single-crystal, polymer-stabilized BPs whose inheren tliquid nature, fast dynamics, and long-range crystalline order can be fully exploited.