Thermally reconfigurable monoclinic nematic colloidal fluids

Mundoor, Haridas; Wu, Jin-Sheng; Wensink, H. H.; Smalyukh, Ivan I.

doi:10.1038/s41586-021-03249-0

Cited by 30 publications

(39 citation statements)

References 48 publications

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“…[ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ] This may lead to technological applications ranging from smart windows to electro‐optic and photonic devices, [ 12 , 13 ] as well as to a fertile ground for new fundamental science. [ 3 ] In the latter case, combining colloidal nanoparticles with nematic fluid hosts already led to the discovery of ferromagnetic, [ 4 , 5 , 6 , 7 ] orthorhombic, [ 10 ] and monoclinic [ 19 ] nematic LC order and triclinic and other colloidal crystals, [ 9 ] but potentially even a much larger range of possibilities can be accessed by dispersions of nanoparticles with various symmetries and topological characteristics. However, realization of diverse mesoscale soft matter composites is hindered by a limited inventory of nanoparticles demonstrated to form stable LC colloidal dispersions with orientational correlations between the anisotropic nanoparticle and the host medium.…”

Section: Introductionmentioning

confidence: 99%

Nematic Order, Plasmonic Switching and Self‐Patterning of Colloidal Gold Bipyramids

et al. 2021

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Dispersing inorganic colloidal nanoparticles within nematic liquid crystals provides a versatile platform both for forming new soft matter phases and for predefining physical behavior through mesoscale molecular-colloidal self-organization. However, owing to formation of particle-induced singular defects and complex elasticity-mediated interactions, this approach has been implemented mainly just for colloidal nanorods and nanoplatelets, limiting its potential technological utility. Here, orientationally ordered nematic colloidal dispersions are reported of pentagonal gold bipyramids that exhibit narrow but controlled polarization-dependent surface plasmon resonance spectra and facile electric switching. Bipyramids tend to orient with their C 5 rotation symmetry axes along the nematic director, exhibiting spatially homogeneous density within aligned samples. Topological solitons, like heliknotons, allow for spatial reorganization of these nanoparticles according to elastic free energy density within their micrometer-scale structures. With the nanoparticle orientations slaved to the nematic director and being switched by low voltages ≈1 V within a fraction of a second, these plasmonic composite materials are of interest for technological uses like color filters and plasmonic polarizers, as well as may lead to the development of unusual nematic phases, like pentatic liquid crystals.

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Section: Introductionmentioning

confidence: 99%

Nematic Order, Plasmonic Switching and Self‐Patterning of Colloidal Gold Bipyramids

et al. 2021

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“…[33][34][35] A LdG = −1.72 × 10 5 J m −3 , B LdG = −2.12 × 10 6 J m −3 , C LdG = 1.73 × 10 6 J m −3 , S eq = 0.533, K 11 = 6. Simulation of Polarizing Optical Microscopy Images: The polarizing optical microscopy images were obtained by using the Jones matrix method, [49] where the multiplication of Jones matrices corresponds to the polarizer, analyzer, 530 nm phase retardation plate, silicon wafer, and LC layers with defined patterns of the optical axis orientations. The LC volume was divided into tens of layers, and each layer was treated as a phase retardation plate with spatially varying optical axis and retardation.…”

Section: Methodsmentioning

confidence: 99%

Fabrication of Arrays of Topological Solitons in Patterned Chiral Liquid Crystals for Real‐Time Observation of Morphogenesis

et al. 2022

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Topological solitons have knotted continuous field configurations embedded in a uniform background, and occur in cosmology, biology, and electromagnetism. However, real‐time observation of their morphogenesis and dynamics is still challenging because their size and timescale are enormously large or tiny. Liquid crystal (LC) structures are promising candidates for a model‐system to study the morphogenesis of topological solitons, enabling direct visualization due to the proper size and timescale. Here, a new way is found to rationalize the real‐time observation of the generation and transformation of topological solitons using cholesteric LCs confined in patterned substrates. The experimental demonstration shows the topologically protected structures arise via the transformation of topological defects. Numerical modeling based on minimization of free energy closely reconstructs the experimental findings. The fundamental insights obtained from the direct observations pose new theoretical challenges in understanding the morphogenesis of different types of topological solitons within a broad range of scales.

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“…Boundary conditions at the colloids’ surface determine n ( r )-deformations around the colloidal particles immersed into LC and formation of the corresponding elastic multipoles. ,, Therefore, controlling the boundary conditions especially when colloids already are mixed in the dispersions can affect the self-assembly of colloidal particles resulting in different fluid materials with new symmetry. − Examples of boundary conditions that can be obtained for LC molecules using specific alignment agents at different colloidal particles described in this article are summarized in Table . One of the methods of controlling the type of anchoring at the colloids’ surface is using electrostatic charging of their surface (Figure ).…”

Section: Liquid Crystal Colloids Fabrication Methodsmentioning

confidence: 99%

Design and Preparation of Nematic Colloidal Particles

2022

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Colloidal systems are abundant in technology, in biomedical settings, and in our daily life. The so-called “colloidal atoms” paradigm exploits interparticle interactions to self-assemble colloidal analogs of atomic and molecular crystals, liquid crystal glasses, and other types of condensed matter from nanometer- or micrometer-sized colloidal building blocks. Nematic colloids, which comprise colloidal particles dispersed within an anisotropic nematic fluid host medium, provide a particularly rich variety of physical behaviors at the mesoscale, not only matching but even exceeding the diversity of structural and phase behavior in conventional atomic and molecular systems. This feature article, using primarily examples of works from our own group, highlights recent developments in the design, fabrication, and self-assembly of nematic colloidal particles, including the capabilities of preprogramming their behavior by controlling the particle’s surface boundary conditions for liquid crystal molecules at the colloidal surfaces as well as by defining the shape and topology of the colloidal particles. Recent progress in defining particle-induced defects, elastic multipoles, self-assembly, and dynamics is discussed along with open issues and challenges within this research field.

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Thermally reconfigurable monoclinic nematic colloidal fluids

Cited by 30 publications

References 48 publications

Nematic Order, Plasmonic Switching and Self‐Patterning of Colloidal Gold Bipyramids

Nematic Order, Plasmonic Switching and Self‐Patterning of Colloidal Gold Bipyramids

Fabrication of Arrays of Topological Solitons in Patterned Chiral Liquid Crystals for Real‐Time Observation of Morphogenesis

Design and Preparation of Nematic Colloidal Particles

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