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An important goal of the modern soft matter science is to discover new self-assembly modalities to precisely control the placement of small particles in space. Spatial inhomogeneity of liquid crystals offers the capability to organize colloids in certain regions such as the cores of the topological defects. Here we report two self-assembly modes of nanoparticles in linear defects-disclinations in a lyotropic colloidal cholesteric liquid crystal: a continuous helicoidal thread and a periodic array of discrete beads. The beads form one-dimensional arrays with a periodicity that matches half a pitch of the cholesteric phase. The periodic assembly is governed by the anisotropic surface tension and elasticity at the interface of beads with the liquid crystal. This mode of self-assembly of nanoparticles in disclinations expands our ability to use topological defects in liquid crystals as templates for the organization of nanocolloids. [ABSTRACT FROM AUTHOR]

We report composite stimulus-responsive cholesteric catalytically active microgels derived from filamentous supramolecular building blocks: cellulose nanocrystals (CNCs). The variation in the microgel dimensions and pitch in response to the change in ambient conditions was governed by the polymer component. The cholesteric morphology of the microgels resulted from the self-organization of CNCs in spherical confinement. The microgels exhibited excellent structural integrity and functioned as microreactors in catalytic hydrolysis reactions and in the synthesis of metal nanoparticles. Because of these collective properties, the reported microgels show much promise for application in the design of functional responsive materials. [ABSTRACT FROM AUTHOR]

Incorporation of metal nanoparticles in chiral (Ch) films of cellulose nanocrystals (CNCs) enhances nanoparticle plasmon resonances, due to the coupling of the intrinsic properties of the plasmonic guest and the photonic properties of the Ch‐CNC host. In contrast with previous reports, the properties of the Ch‐CNC host are focused and an effective strategy is developed for tuning the optical polarization rotation of the composite films formed by the CNCs and gold nanoparticles. A twofold enhancement in the polarization rotation power of the composite Ch‐CNC films, with an insignificant change in the incurred optical losses, is achieved by varying the density and dimensions of gold nanoparticles embedded in the Ch‐CNC films. For such films, a new approach is developed to obtain broadband circular dichroism by fabricating films from mixtures of CNC suspensions ultrasonicated for different time intervals. These new findings enable fine‐tuning of the power and spectral range of the polarization rotation and offer a novel strategy for the fabrication of broadband reflectors and polarizers, smart solar windows, and detectors for circularly polarized light. [ABSTRACT FROM AUTHOR]

Spherical‐shape cholesteric (Ch) photonic films offer promising applications such as omnidirectional lasing and broadband reflection. Here, a strategy is reported for the fabrication of photonic Ch films by the self‐assembly of cellulose nanocrystals (CNCs) in semi‐spherical cavities. It is shown that film structure and photonic properties are controlled by the film curvature, the composition of the precursor CNC suspension, and its liquid crystalline or isotropic state. The effect of curvature of the drying Ch‐CNC films coupled with the restricted mobility of CNCs during film preparation results in the variation in pitch and helical axis inclination, thus leading to broadband reflectance properties of the films. The role of curvature of the Ch‐CNC films is underlined by comparing their distinct properties with those of planar films with the same composition. These findings provide a novel insight into the design and development of biomimetic photonic Ch films. Semi‐spherical cholesteric cellulose nanocrystal (CNC) films with tunable optical properties are fabricated by exploring the interplay between the curvature, the composition and state of the precursor CNC suspension, and the film structure and optical properties. The combination of photonic properties and spherical shape results in a broadband reflection covering the entire spectral range. [ABSTRACT FROM AUTHOR]

The article discusess a study conducted for achieving precise organization of nanoparticles (NPs) in three-dimensional space. It examines morphogenesis of nanoparticle assemblies and a cholesteric liquid crystalline host formed by cellulose nanocrystals for experiencing marked changes in shape and structure as a function of concentration. It mentions increase in NP loading triggers reversible droplet transformation to gain a core-shell morphology with an isotropic core.