1
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Senyuk B, Wu JS, Smalyukh II. Out-of-equilibrium interactions and collective locomotion of colloidal spheres with squirming of nematoelastic multipoles. Proc Natl Acad Sci U S A 2024; 121:e2322710121. [PMID: 38652740 PMCID: PMC11067049 DOI: 10.1073/pnas.2322710121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 03/14/2024] [Indexed: 04/25/2024] Open
Abstract
Many living and artificial systems show similar emergent behavior and collective motions on different scales, starting from swarms of bacteria to synthetic active particles, herds of mammals, and crowds of people. What all these systems often have in common is that new collective properties like flocking emerge from interactions between individual self-propelled or driven units. Such systems are naturally out-of-equilibrium and propel at the expense of consumed energy. Mimicking nature by making self-propelled or externally driven particles and studying their individual and collective motility may allow for deeper understanding of physical underpinnings behind collective motion of large groups of interacting objects or beings. Here, using a soft matter system of colloids immersed into a liquid crystal, we show that resulting so-called nematoelastic multipoles can be set into a bidirectional locomotion by external oscillating electric fields. Out-of-equilibrium elastic interactions between such colloidal objects lead to collective flock-like behaviors emerging from time-varying elasticity-mediated interactions between externally driven propelling particles. Repulsive elastic interactions in the equilibrium state can be turned into attractive interactions in the out-of-equilibrium state under applied external electric fields. We probe this behavior at different number densities of colloidal particles and show that particles in dense dispersions collectively select the same direction of a coherent motion due to elastic interactions between near neighbors. In our experimentally implemented design, their motion is highly ordered and without clustering or jamming often present in other colloidal transport systems, which is promising for technological and fundamental-science applications, like nano-cargo transport, out-of-equilibrium assembly, and microrobotics.
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Affiliation(s)
- Bohdan Senyuk
- Department of Physics, University of Colorado, Boulder, CO80309
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM), Hiroshima University, Higashi-Hiroshima, Hiroshima739-0046, Japan
| | - Jin-Sheng Wu
- Department of Physics, University of Colorado, Boulder, CO80309
| | - Ivan I. Smalyukh
- Department of Physics, University of Colorado, Boulder, CO80309
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM), Hiroshima University, Higashi-Hiroshima, Hiroshima739-0046, Japan
- Materials Science and Engineering Program, University of Colorado, Boulder, CO80309
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO80309
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2
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S A, V S D, More P, Pujala RK, Dhara S. Electrophoretic propulsion of matchstick-shaped magnetodielectric particles in the presence of external magnetic fields in a nematic liquid crystal. SOFT MATTER 2024; 20:535-545. [PMID: 38126395 DOI: 10.1039/d3sm01382k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Synthesis of micro- and nanoparticles of pre-designed shape and surface properties is an integral part of soft and synthetic active matter. We report synthesis of matchstick-shaped (MS) magnetodielectric particles and demonstrate their potential as active agents with field-controllable trajectories in a nematic liquid crystal (NLC). The MS particles with homeotropic anchoring in NLCs align either parallel or perpendicular to the director depending on the dipolar or quadrupolar director distortions. When subjected to transverse electric and magnetic fields, the particles experience electric and magnetic torques trying to align them in the respective field directions. At equilibrium, the long axis is tilted at an angle with respect to the director. The change in orientation alters the surrounding elastic distortion, which results in unbalanced electroosmotic flows. These flows provide the necessary impetus for propelling the particles in various directions with different velocities depending on their orientations.
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Affiliation(s)
- Archana S
- School of Physics, University of Hyderabad, Hyderabad-500046, India.
| | - Devika V S
- School of Physics, University of Hyderabad, Hyderabad-500046, India.
| | - Prasanna More
- Department of Physics, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati, Andhra Pradesh, 517507, India
| | - Ravi Kumar Pujala
- Department of Physics, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati, Andhra Pradesh, 517507, India
| | - Surajit Dhara
- School of Physics, University of Hyderabad, Hyderabad-500046, India.
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3
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Rhee K, Tukova A, Tavakkoli Yaraki M, Wang Y. Nanosupernova: a new anisotropic nanostructure for SERS. NANOSCALE 2023; 15:2087-2095. [PMID: 36647920 DOI: 10.1039/d2nr05287c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Gold and/or silver nanostars are interesting anisotropic nanoparticles that have been used in surface-enhanced Raman scattering (SERS). In particular SERS nanotags consisting of gold nanostars and Raman reporter molecules have been widely utilised in biosensing and bioimaging. To improve the SERS activity of gold/silver nanostars, this paper details the development of a simple synthesis method that results in the formation of quasi-spherical SERS nanotags and larger highly anisotropic nanoparticles with a novel structure, which we have designated nanosupernova. The resulting SERS nanotags and nanosupernova contain gold/silver nanostars at their core, a self-assembled monolayer of Raman reporter molecules, and a final silver coating. The silver coating is the essential step responsible for the formation of the two types of particles, with incubation time, and type of Raman reporter molecule, the defining factor as to which forms. We discovered that the Raman reporter molecule, 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB), plays a crucial role in controlling the morphology of nanosupernova. We believe the larger highly anisotropic nanoparticles will open new applications in material sciences and in optical and electronic devices in the future.
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Affiliation(s)
- Kristina Rhee
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Ryde, New South Wales 2109, Australia.
| | - Anastasiia Tukova
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Ryde, New South Wales 2109, Australia.
| | - Mohammad Tavakkoli Yaraki
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Ryde, New South Wales 2109, Australia.
| | - Yuling Wang
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Ryde, New South Wales 2109, Australia.
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Martín-Sánchez C, Sánchez-Iglesias A, Barreda-Argüeso JA, Polian A, Liz-Marzán LM, Rodríguez F. Behavior of Au Nanoparticles under Pressure Observed by In Situ Small-Angle X-ray Scattering. ACS NANO 2023; 17:743-751. [PMID: 36525616 PMCID: PMC9835983 DOI: 10.1021/acsnano.2c10643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
The mechanical properties and stability of metal nanoparticle colloids under high-pressure conditions are investigated by means of optical extinction spectroscopy and small-angle X-ray scattering (SAXS), for colloidal dispersions of gold nanorods and gold nanospheres. SAXS allows us to follow in situ the structural evolution of the nanoparticles induced by pressure, regarding both nanoparticle size and shape (form factor) and their aggregation through the interparticle correlation function S(q) (structure factor). The observed behavior changes under hydrostatic and nonhydrostatic conditions are discussed in terms of liquid solidification processes yielding nanoparticle aggregation. We show that pressure-induced diffusion and aggregation of gold nanorods take place after solidification of the solvent. The effect of nanoparticle shape on the aggregation process is additionally discussed.
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Affiliation(s)
- Camino Martín-Sánchez
- MALTA
Consolider, Departamento CITIMAC, Facultad de Ciencias, University de Cantabria, Santander39005, Spain
- Faculté
des Sciences, Département de Chimie Physique, Université de Genève, 30 Quai Ernest-Ansermet, CH-1211Genève, Switzerland
| | - Ana Sánchez-Iglesias
- CIC
biomaGUNE, Basque Research and Technology Alliance (BRTA), Paseo de Miramón 194, Donostia-San Sebastián20014, Spain
| | | | - Alain Polian
- Synchrotron
SOLEIL, L’Orme
des Merisiers St.Aubin, BP48, 91192Gif-sur-Yvette, France
- Sorbonne
Université, UMR CNRS 7590, Institut de Minéralogie de
Physique des Matériaux et de Cosmochimie, IMPMC, 75005Paris, France
| | - Luis M. Liz-Marzán
- CIC
biomaGUNE, Basque Research and Technology Alliance (BRTA), Paseo de Miramón 194, Donostia-San Sebastián20014, Spain
- Ikerbasque,
Basque Foundation for Science, Bilbao43018, Spain
- Centro
de Investigación Biomédica en Red, Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Paseo de Miramón 194, Donostia-San Sebastián20014, Spain
| | - Fernando Rodríguez
- MALTA
Consolider, Departamento CITIMAC, Facultad de Ciencias, University de Cantabria, Santander39005, Spain
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5
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Senyuk B, Meng C, Smalyukh II. Design and Preparation of Nematic Colloidal Particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9099-9118. [PMID: 35866261 DOI: 10.1021/acs.langmuir.2c00611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
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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Affiliation(s)
- Bohdan Senyuk
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
| | - Cuiling Meng
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
- Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Colorado 80309, United States
- Soft Materials Research Center and Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, United States
- Chemical Physics Program, Departments of Chemistry and Physics, University of Colorado, Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, United States
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6
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Ettinger S, Dietrich CF, Mishra CK, Miksch C, Beller DA, Collings PJ, Yodh AG. Rods in a lyotropic chromonic liquid crystal: emergence of chirality, symmetry-breaking alignment, and caged angular diffusion. SOFT MATTER 2022; 18:487-495. [PMID: 34851348 DOI: 10.1039/d1sm01209f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In lyotropic chromonic liquid crystals (LCLCs), twist distortion of the nematic director costs much less energy than splay or bend distortion. This feature leads to novel mirror-symmetry breaking director configurations when the LCLCs are confined by interfaces or contain suspended particles. Spherical colloids in an aligned LCLC nematic phase, for example, induce chiral director perturbations ("twisted tails"). The asymmetry of rod-like particles in an aligned LCLC offer a richer set of possibilities due to their aspect ratio (α) and mean orientation angle (〈θ〉) between their long axis and the uniform far-field director. Here we report on the director configuration, equilibrium orientation, and angular diffusion of rod-like particles with planar anchoring suspended in an aligned LCLC. Video microscopy reveals, counterintuitively, that two-thirds of the rods have an angled equilibrium orientation (〈θ〉 ≠ 0) that decreases with increasing α, while only one-third of the rods are aligned (〈θ〉 = 0). Polarized optical video-microscopy and Landau-de Gennes numerical modeling demonstrate that the angled and aligned rods are accompanied by distinct chiral director configurations. Angled rods have a longitudinal mirror plane (LMP) parallel to their long axis and approximately parallel to the substrate walls. Aligned rods have a transverse and longitudinal mirror plane (TLMP), where the transverse mirror plane is perpendicular to the rod's long axis. Effectively, the small twist elastic constant of LCLCs promotes chiral director configurations that modify the natural tendency of rods to orient along the far-field director. Additional diffusion experiments confirm that rods are angularly confined with strength that depends on α.
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Affiliation(s)
- Sophie Ettinger
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Clarissa F Dietrich
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Chandan K Mishra
- Discipline of Physics, Indian Institute of Technology (IIT) Gandhinagar, Palaj, Gandhinagar, Gujarat 382355, India
| | - Cornelia Miksch
- Max Planck Institute of Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Daniel A Beller
- Department of Physics, University of California, Merced, CA, 95343, USA
| | - Peter J Collings
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA, 19081, USA
| | - A G Yodh
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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7
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Senyuk B, Adufu RE, Smalyukh II. Electrically Powered Locomotion of Dual-Nature Colloid-Hedgehog and Colloid-Umbilic Topological and Elastic Dipoles in Liquid Crystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:689-697. [PMID: 34990137 DOI: 10.1021/acs.langmuir.1c02546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Colloidal particles in liquid crystals tend to induce topological defects and distortions of the molecular alignment within the surrounding anisotropic host medium, which results in elasticity-mediated interactions not accessible to their counterparts within isotropic fluid hosts. Such particle-induced coronae of perturbed nematic order are highly responsive to external electric fields, even when the uniformly aligned host medium away from particles exhibits no response to fields below the realignment threshold. Here we harness the nonreciprocal nature of these facile electric responses to demonstrate colloidal locomotion. Oscillations of the electric field prompt repetitive deformations of the corona of dipolar elastic distortions around the colloidal inclusions, which upon appropriately designed electric driving synchronize the displacement directions. We observe the colloid-hedgehog dipole accompanied by an umbilical defect in the tilt directionality field (c-field), along with the texture of elastic distortions that evolves with a change in the applied voltage. The temporal out-of-equilibrium evolution of the director and c-field distortions around particles when the voltage is turned on and off is not invariant upon reversal of time, prompting lateral translations and interactions that markedly differ from those accessible to these colloids under equilibrium conditions. Our findings may lead to both technological and fundamental science applications of nematic colloids as both model reconfigurable colloidal systems and as mesostructured materials with predesigned temporal evolution of structure and composition.
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Affiliation(s)
- Bohdan Senyuk
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
| | - Richmond E Adufu
- Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
- Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Colorado 80309, United States
- Soft Materials Research Center and Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, United States
- Chemical Physics Program, Departments of Chemistry and Physics, University of Colorado, Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, United States
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8
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Zhang M, Lindner-D’Addario M, Roohnikan M, Toader V, Lennox RB, Reven L. Polymer Functionalized Nanoparticles in Blue Phase LC: Effect of Particle Shape. NANOMATERIALS 2021; 12:nano12010091. [PMID: 35010041 PMCID: PMC8746361 DOI: 10.3390/nano12010091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/10/2021] [Accepted: 12/19/2021] [Indexed: 02/02/2023]
Abstract
Ethylene oxide oligomers and polymers, free and tethered to gold nanoparticles, were dispersed in blue phase liquid crystals (BPLC). Gold nanospheres (AuNPs) and nanorods (AuNRs) were functionalized with thiolated ethylene oxide ligands with molecular weights ranging from 200 to 5000 g/mol. The BPLC mixture (ΔTBP ~6 °C) was based on the mesogenic acid heterodimers, n-hexylbenzoic acid (6BA) and n-trans-butylcyclohexylcarboxylic acid (4-BCHA) with the chiral dopant (R)-2-octyl 4-[4-(hexyloxy)benzoyloxy]benzoate. The lowest molecular weight oligomer lowered and widened the BP range but adding AuNPs functionalized with the same ligand had little effect. Higher concentrations or molecular weights of the ligands, free or tethered to the AuNPs, completely destabilized the BP. Mini-AuNRs functionalized with the same ligands lowered and widened the BP temperature range with longer mini-AuNRs having a larger effect. In contrast to the AuNPs, the mini-AuNRs with the higher molecular weight ligands widened rather than destabilized the BP, though the lowest MW ligand yielded the largest BP range, (ΔTBP > 13 °C). The different effects on the BP may be due to the AuNPs accumulating at singular defect sites whereas the mini-AuNRs, with diameters smaller than that of the disclination lines, can more efficiently fill in the BP defects.
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9
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Senyuk B, Mundoor H, Smalyukh II, Wensink HH. Nematoelasticity of hybrid molecular-colloidal liquid crystals. Phys Rev E 2021; 104:014703. [PMID: 34412251 DOI: 10.1103/physreve.104.014703] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/25/2021] [Indexed: 11/07/2022]
Abstract
Colloidal rods immersed in a thermotropic liquid-crystalline solvent are at the basis of so-called hybrid liquid crystals, which are characterized by tunable nematic fluidity with symmetries ranging from conventional uniaxial nematic or antinematic to orthorhombic [Mundoor et al., Science 360, 768 (2018)SCIEAS0036-807510.1126/science.aap9359]. We provide a theoretical analysis of the elastic moduli of such systems by considering interactions between the individual rods with the embedding solvent through surface-anchoring forces, as well as steric and electrostatic interactions between the rods themselves. For uniaxial systems, the presence of colloidal rods generates a marked increase of the splay elasticity, which we found to be in quantitative agreement with experimental measurements. For orthorhombic hybrid liquid crystals, we provide estimates of all 12 elastic moduli and show that only a small subset of those elastic constants play a relevant role in describing the nematoelastic properties. The complexity and possibilities related to identifying the elastic moduli in experiments are briefly discussed.
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Affiliation(s)
- B Senyuk
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - H Mundoor
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - I I Smalyukh
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.,Department of Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA.,Chemical Physics Program, Departments of Chemistry and Physics, University of Colorado, Boulder, Colorado 80309, USA.,Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, USA
| | - H H Wensink
- Laboratoire de Physique des Solides, Université Paris-Saclay & CNRS, UMR 8502, 91405 Orsay, France
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10
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Senyuk B, Mozaffari A, Crust K, Zhang R, de Pablo JJ, Smalyukh II. Transformation between elastic dipoles, quadrupoles, octupoles, and hexadecapoles driven by surfactant self-assembly in nematic emulsion. SCIENCE ADVANCES 2021; 7:7/25/eabg0377. [PMID: 34144988 PMCID: PMC8213233 DOI: 10.1126/sciadv.abg0377] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 05/05/2021] [Indexed: 06/12/2023]
Abstract
Emulsions comprising isotropic fluid drops within a nematic host are of interest for applications ranging from biodetection to smart windows, which rely on changes of molecular alignment structures around the drops in response to chemical, thermal, electric, and other stimuli. We show that absorption or desorption of trace amounts of common surfactants can drive continuous transformations of elastic multipoles induced by the droplets within the uniformly aligned nematic host. Out-of-equilibrium dynamics of director structures emerge from a controlled self-assembly or desorption of different surfactants at the drop-nematic interfaces, with ensuing forward and reverse transformations between elastic dipoles, quadrupoles, octupoles, and hexadecapoles. We characterize intertransformations of droplet-induced surface and bulk defects, probe elastic pair interactions, and discuss emergent prospects for fundamental science and applications of the reconfigurable nematic emulsions.
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Affiliation(s)
- Bohdan Senyuk
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
| | - Ali Mozaffari
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - Kevin Crust
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
| | - Rui Zhang
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR
| | - Juan J de Pablo
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
- Center for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Ivan I Smalyukh
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA.
- Department of Electrical, Computer, and Energy Engineering and Materials Science and Engineering Program, University of Colorado, Boulder, CO 80309, USA
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO 80309, USA
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11
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Lavrentovich OD. Design of nematic liquid crystals to control microscale dynamics. LIQUID CRYSTALS REVIEWS 2021; 8:59-129. [PMID: 34956738 PMCID: PMC8698256 DOI: 10.1080/21680396.2021.1919576] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 04/11/2021] [Indexed: 05/25/2023]
Abstract
The dynamics of small particles, both living such as swimming bacteria and inanimate, such as colloidal spheres, has fascinated scientists for centuries. If one could learn how to control and streamline their chaotic motion, that would open technological opportunities in the transformation of stored or environmental energy into systematic motion, with applications in micro-robotics, transport of matter, guided morphogenesis. This review presents an approach to command microscale dynamics by replacing an isotropic medium with a liquid crystal. Orientational order and associated properties, such as elasticity, surface anchoring, and bulk anisotropy, enable new dynamic effects, ranging from the appearance and propagation of particle-like solitary waves to self-locomotion of an active droplet. By using photoalignment, the liquid crystal can be patterned into predesigned structures. In the presence of the electric field, these patterns enable the transport of solid and fluid particles through nonlinear electrokinetics rooted in anisotropy of conductivity and permittivity. Director patterns command the dynamics of swimming bacteria, guiding their trajectories, polarity of swimming, and distribution in space. This guidance is of a higher level of complexity than a simple following of the director by rod-like microorganisms. Namely, the director gradients mediate hydrodynamic interactions of bacteria to produce an active force and collective polar modes of swimming. The patterned director could also be engraved in a liquid crystal elastomer. When an elastomer coating is activated by heat or light, these patterns produce a deterministic surface topography. The director gradients define an activation force that shapes the elastomer in a manner similar to the active stresses triggering flows in active nematics. The patterned elastomer substrates could be used to define the orientation of cells in living tissues. The liquid-crystal guidance holds a major promise in achieving the goal of commanding microscale active flows.
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Affiliation(s)
- Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Department of Physics, Materials Science Graduate Program, Kent State University, Kent, OH 44242, USA
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12
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Mundoor H, Wu JS, Wensink HH, Smalyukh II. Thermally reconfigurable monoclinic nematic colloidal fluids. Nature 2021; 590:268-274. [PMID: 33568825 DOI: 10.1038/s41586-021-03249-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 11/26/2020] [Indexed: 01/30/2023]
Abstract
Fundamental relationships are believed to exist between the symmetries of building blocks and the condensed matter phases that they form1. For example, constituent molecular and colloidal rods and disks impart their uniaxial symmetry onto nematic liquid crystals, such as those used in displays1,2. Low-symmetry organizations could form in mixtures of rods and disks3-5, but entropy tends to phase-separate them at the molecular and colloidal scales, whereas strong elasticity-mediated interactions drive the formation of chains and crystals in nematic colloids6-11. To have a structure with few or no symmetry operations apart from trivial ones has so far been demonstrated to be a property of solids alone1, but not of their fully fluid condensed matter counterparts, even though such symmetries have been considered theoretically12-15 and observed in magnetic colloids16. Here we show that dispersing highly anisotropic charged colloidal disks in a nematic host composed of molecular rods provides a platform for observing many low-symmetry phases. Depending on the temperature, concentration and surface charge of the disks, we find nematic, smectic and columnar organizations with symmetries ranging from uniaxial1,2 to orthorhombic17-21 and monoclinic12-15. With increasing temperature, we observe unusual transitions from less- to more-ordered states and re-entrant22 phases. Most importantly, we demonstrate the presence of reconfigurable monoclinic colloidal nematic order, as well as the possibility of thermal and magnetic control of low-symmetry self-assembly2,23,24. Our experimental findings are supported by theoretical modelling of the colloidal interactions between disks in the nematic host and may provide a route towards realizing many low-symmetry condensed matter phases in systems with building blocks of dissimilar shapes and sizes, as well as their technological applications.
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Affiliation(s)
- Haridas Mundoor
- Department of Physics, University of Colorado, Boulder, CO, USA
| | - Jin-Sheng Wu
- Chemical Physics Program, Departments of Chemistry and Physics, University of Colorado, Boulder, CO, USA
| | - Henricus H Wensink
- Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, Orsay, France
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado, Boulder, CO, USA. .,Chemical Physics Program, Departments of Chemistry and Physics, University of Colorado, Boulder, CO, USA. .,Materials Science and Engineering Program, Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO, USA. .,Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO, USA.
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13
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Yuan Y, Tasinkevych M, Smalyukh II. Colloidal interactions and unusual crystallization versus de-mixing of elastic multipoles formed by gold mesoflowers. Nat Commun 2020; 11:188. [PMID: 31924770 PMCID: PMC6954209 DOI: 10.1038/s41467-019-14031-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 12/12/2019] [Indexed: 11/22/2022] Open
Abstract
Colloidal interactions in nematic liquid crystals can be described as interactions between elastic multipoles that depend on particle shape, topology, chirality, boundary conditions and induced topological defects. Here, we describe a nematic colloidal system consisting of mesostructures of gold capable of inducing elastic multipoles of different order. Elastic monopoles are formed by relatively large asymmetric mesoflower particles, for which gravity and elastic torque balancing yields monopole-type interactions. High-order multipoles are instead formed by smaller mesoflowers with a myriad of shapes corresponding to multipoles of different orders, consistent with our computer simulations based on free energy minimization. We reveal unexpected many-body interactions in this colloidal system, ranging from de-mixing of elastic monopoles to a zoo of unusual colloidal crystals formed by high-order multipoles like hexadecapoles. Our findings show that gold mesoflowers may serve as a designer toolkit for engineering colloidal interaction and self-assembly, potentially exceeding that in atomic and molecular systems. Elasticity-mediated particle interaction in a hosting medium holds promise for material engineering of unusual structures. Yuan et al. show that the gold microparticles can induce elastic multipoles of different symmetries when dispersed in a nematic liquid crystal as building blocks for various crystals.
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Affiliation(s)
- Ye Yuan
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA
| | - Mykola Tasinkevych
- Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, P-1749-016, Lisboa, Portugal.,Centro de Física Teórica e Computacional, Universidade de Lisboa, Campo Grande, P-1749-016, Lisboa, Portugal
| | - Ivan I Smalyukh
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA. .,Department of Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program, University of Colorado, Boulder, CO, 80309, USA. .,Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO, 80309, USA.
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14
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Lesiak P, Bednarska K, Lewandowski W, Wójcik M, Polakiewicz S, Bagiński M, Osuch T, Markowski K, Orzechowski K, Makowski M, Bolek J, Woliński TR. Self-Organized, One-Dimensional Periodic Structures in a Gold Nanoparticle-Doped Nematic Liquid Crystal Composite. ACS NANO 2019; 13:10154-10160. [PMID: 31433620 DOI: 10.1021/acsnano.9b03302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Composite structures exhibiting a periodic arrangement of building blocks can be found in natural systems at different length scales. Recreating such systems in artificial composites using the principles of self-assembly has been a great challenge, especially for 1D microscale systems. Here, we present a purposely designed composite material consisting of gold nanoparticles and a nematic liquid crystal matrix that has the ability to self-create a periodic structure in the form of a one-dimensional photonic lattice through a phase separation process occurring in a confined space. Our strategy is based on the use of a thermoswitchable medium that reversibly and quickly responds to both heating and cooling. We find that the period of the structure is strongly related to the size of the confining space. We believe that our findings will allow us to not only better understand the phase separation process in multicomponent soft/colloid mixtures with useful optical properties but also improve our understanding of the precise assembly of advanced materials into one-dimensional periodic systems, with prospective applications in future photonic technologies.
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Affiliation(s)
- Piotr Lesiak
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warszawa , Poland
| | - Karolina Bednarska
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warszawa , Poland
| | - Wiktor Lewandowski
- Faculty of Chemistry , University of Warsaw , ul. Pasteura 1 , 02-093 Warszawa , Poland
| | - Michał Wójcik
- Faculty of Chemistry , University of Warsaw , ul. Pasteura 1 , 02-093 Warszawa , Poland
| | - Sylwia Polakiewicz
- Faculty of Chemistry , University of Warsaw , ul. Pasteura 1 , 02-093 Warszawa , Poland
| | - Maciej Bagiński
- Faculty of Chemistry , University of Warsaw , ul. Pasteura 1 , 02-093 Warszawa , Poland
| | - Tomasz Osuch
- Faculty of Electronics and Information Technology, Institute of Electronic Systems , Warsaw University of Technology , Nowowiejska 15/19 , 00-665 Warszawa , Poland
| | - Konrad Markowski
- Faculty of Electronics and Information Technology, Institute of Electronic Systems , Warsaw University of Technology , Nowowiejska 15/19 , 00-665 Warszawa , Poland
| | - Kamil Orzechowski
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warszawa , Poland
| | - Michał Makowski
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warszawa , Poland
| | - Jan Bolek
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warszawa , Poland
| | - Tomasz R Woliński
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warszawa , Poland
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15
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Mundoor H, Senyuk B, Almansouri M, Park S, Fleury B, Smalyukh II. Electrostatically controlled surface boundary conditions in nematic liquid crystals and colloids. SCIENCE ADVANCES 2019; 5:eaax4257. [PMID: 31555742 PMCID: PMC6754225 DOI: 10.1126/sciadv.aax4257] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 08/23/2019] [Indexed: 05/30/2023]
Abstract
Differing from isotropic fluids, liquid crystals exhibit highly anisotropic interactions with surfaces, which define boundary conditions for the alignment of constituent rod-like molecules at interfaces with colloidal inclusions and confining substrates. We show that surface alignment of the nematic molecules can be controlled by harnessing the competing aligning effects of surface functionalization and electric field arising from surface charging and bulk counterions. The control of ionic content in the bulk and at surfaces allows for tuning orientations of shape-anisotropic particles like platelets within an aligned nematic host and for changing the orientation of director relative to confining substrates. The ensuing anisotropic elastic and electrostatic interactions enable colloidal crystals with reconfigurable symmetries and orientations of inclusions.
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Affiliation(s)
- Haridas Mundoor
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
| | - Bohdan Senyuk
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
| | - Mahmoud Almansouri
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
| | - Sungoh Park
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
| | - Blaise Fleury
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
| | - Ivan I. Smalyukh
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
- Department of Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program, University of Colorado, Boulder, CO 80309, USA
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory, University of Colorado, Boulder, CO 80309, USA
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16
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Elastic colloidal monopoles and reconfigurable self-assembly in liquid crystals. Nature 2019; 570:214-218. [DOI: 10.1038/s41586-019-1247-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 04/05/2019] [Indexed: 11/09/2022]
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17
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Yuan Y, Abuhaimed GN, Liu Q, Smalyukh II. Self-assembled nematic colloidal motors powered by light. Nat Commun 2018; 9:5040. [PMID: 30487599 PMCID: PMC6261955 DOI: 10.1038/s41467-018-07518-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/02/2018] [Indexed: 01/07/2023] Open
Abstract
Biological motors are marvels of nature that inspire creation of their synthetic counterparts with comparable nanoscale dimensions, high efficiency and diverse functions. Molecular motors have been synthesized, but obtaining nanomotors through self-assembly remains challenging. Here we describe a self-assembled colloidal motor with a repetitive light-driven rotation of transparent micro-particles immersed in a liquid crystal and powered by a continuous exposure to unstructured ~1 nW light. A monolayer of azobenzene molecules defines how the liquid crystal's optical axis mechanically couples to the particle's surface, as well as how they jointly rotate as the light's polarization changes. The rotating particle twists the liquid crystal, which changes polarization of traversing light. The resulting feedback mechanism yields a continuous opto-mechanical cycle and drives the unidirectional particle spinning, with handedness and frequency robustly controlled by polarization and intensity of light. Our findings may lead to opto-mechanical devices and colloidal machines compatible with liquid crystal display technology.
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Affiliation(s)
- Ye Yuan
- Department of Physics, University of Colorado, Boulder, CO, 80309, USA
| | | | - Qingkun Liu
- Department of Physics, University of Colorado, Boulder, CO, 80309, USA
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado, Boulder, CO, 80309, USA. .,Soft Materials Research Center and Materials Science and Engineering Program, Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, CO, 80309, USA. .,Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO, 80309, USA.
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18
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Allie S, Hegoburu I, Shin MJ, Jung JY, Toader V, Rey A, Soule ER, Reven L. Polymer functionalized nanoparticles in liquid crystals: combining PDLCs with LC nanocomposites. SOFT MATTER 2018; 14:8580-8589. [PMID: 30318545 DOI: 10.1039/c8sm01192c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Liquid crystal (LC)-polymer blends are important stimuli responsive materials already employed in a wide range of applications whereas nanoparticle (NP)-LC blends are an emerging class of nanocomposites. Polymer ligands offer the advantages of synthetic simplicity along with chemical and molecular weight tunability. Here we compare the phase behavior of 5CB blended with poly(ethylene oxide) (PEO) and with gold NPs functionalized with thiolated PEO (AuNP-PEO) as a function of PEO concentration by DSC, POM and 13C NMR spectroscopy. Both PEO and the AuNP-PEO form uniform dispersions in isotropic 5CB and phase separate below the I-N phase transition temperature. Above the PEO crystallization temperature, the PEO/5CB blends show the expected biphasic state of PEO rich-isotropic liquid co-existing with PEO-poor nematic droplets. At PEO concentrations above 10 wt%, nematic 5CB nucleates with PEO crystallization. Both PEO and AuNP-PEO induce homeotropic alignment of the 5CB matrix immediately below TNI. The AuNP-PEO/5CB blends form thermally reversible cellular networks similar to AuNPs functionalized with low molecular weight mesogenic ligands. A thermodynamic model to account for the observed phase behavior is presented.
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Affiliation(s)
- Safiya Allie
- Quebec Centre for Advanced Materials, Department of Chemistry, McGill University, 801 Sherbrooke St. W., Montreal QC H3A 0B8, Canada.
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Mondal S, Majumdar A, Griffiths IM. Nematohydrodynamics for colloidal self-assembly and transport phenomena. J Colloid Interface Sci 2018; 528:431-442. [PMID: 30168421 DOI: 10.1016/j.jcis.2018.05.072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 05/21/2018] [Accepted: 05/21/2018] [Indexed: 11/27/2022]
Abstract
HYPOTHESIS Colloidal particles in a nematic liquid crystal (NLC) exhibit very different behaviour to that observed in an isotropic medium. Such differences arise principally due to the nematic-induced elastic stresses exerted due to the interaction of NLC molecules with interfaces, which compete with traditional fluid viscous stresses on the particle. THEORY A systematic mathematical analysis of particles in an NLC microfluidic channel is performed using the continuum Beris-Edwards framework coupled to the Navier-Stokes equations. We impose strong homeotropic anchoring on the channel walls and weak homeotropic anchoring on the particle surfaces. FINDINGS The viscous and NLC forces act on an individual particle in opposing directions, resulting in a critical location in the channel where the particle experiences zero net force in the direction perpendicular to the flow. For multi-particle aggregation we show that the final arrangement is independent of the initial configuration, but the path towards achieving equilibrium is very different. These results uncover new mechanisms for particle separation and routes towards self-assembly.
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Affiliation(s)
- Sourav Mondal
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
| | - Apala Majumdar
- Department of Mathematical Sciences, University of Bath, Bath BA2 7AY, UK
| | - Ian M Griffiths
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK.
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20
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Wang Q, Liu L, Xu L. Coupling free energy and surface anchoring mechanism in gold nanorod–nematic liquid crystal dispersions. RSC Adv 2018. [DOI: 10.1039/c7ra09378k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dependence of both the induced optical birefringence signals and simulated free energy ftotal with the pump H.
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Affiliation(s)
- Qi Wang
- Key Lab for Micro and Nanophotonic Structures (Ministry of Education)
- Department of Optical Science and Engineering
- School of Information Science and Engineering
- Fudan University
- Shanghai 200433
| | - Liying Liu
- Key Lab for Micro and Nanophotonic Structures (Ministry of Education)
- Department of Optical Science and Engineering
- School of Information Science and Engineering
- Fudan University
- Shanghai 200433
| | - Lei Xu
- Key Lab for Micro and Nanophotonic Structures (Ministry of Education)
- Department of Optical Science and Engineering
- School of Information Science and Engineering
- Fudan University
- Shanghai 200433
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21
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Chen K, Gebhardt OJ, Devendra R, Drazer G, Kamien RD, Reich DH, Leheny RL. Colloidal transport within nematic liquid crystals with arrays of obstacles. SOFT MATTER 2017; 14:83-91. [PMID: 29099121 DOI: 10.1039/c7sm01681f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We have investigated the gravity-driven transport of spherical colloids suspended in the nematic liquid crystal 4-cyano-4'-pentylbiphenyl (5CB) within microfluidic arrays of cylindrical obstacles arranged in a square lattice. Homeotropic anchoring at the surfaces of the obstacles created periodic director-field patterns that strongly influenced the motion of the colloids, whose surfaces had planar anchoring. When the gravitational force was oriented parallel to a principal axis of the lattice, the particles moved along channels between columns of obstacles and displayed pronounced modulations in their velocity. Quantitative analysis indicates that this modulation resulted from a combination of a spatially varying effective drag viscosity and elastic interactions engendered by the periodic director field. The interactions differed qualitatively from a sum of pair-wise interactions between the colloids and isolated obstacles, reflecting the distinct nematic environment created by confinement within the array. As the angle α between the gravitational force and principal axis of the lattice was varied, the velocity did not follow the force but instead locked into a discrete set of directions commensurate with the lattice. The transitions between these directions occurred at values of α that were different from those observed when the spheres were in an isotropic liquid, indicating the ability of the liquid crystal forces to tune the lateral displacement behavior in such devices.
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Affiliation(s)
- Kui Chen
- Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD, USA.
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22
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Silva RS, de Melo PB, Omena L, Nunes AM, da Silva MGA, Meneghetti MR, de Oliveira IN. Temperature dependence of the nonlinear optical response of smectic liquid crystals containing gold nanorods. Phys Rev E 2017; 96:062703. [PMID: 29347296 DOI: 10.1103/physreve.96.062703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Indexed: 06/07/2023]
Abstract
The present study is devoted to the investigation of the nonlinear optical properties of a smectic liquid crystal doped with gold nanorods. Using the Z-scan technique, we investigate the changes in the optical birefringence of a homeotropic sample upon laser exposure, considering the configurations of normal and oblique incidence. Our results reveal that the birefringence variations may be governed by distinct physical mechanisms, depending on the relative angle between the far-field director and the wave vector of the excitation laser beam. In particular, we observe that the position dependence of the far-field transmittance exhibits different behaviors as the incidence angle is changed, indicating that distortions in the beam wavefront may be associated with the thermal lens phenomenon or an optically induced reorientation of the nematic director. The temperature dependence of the nonlinear refractive and absorptive coefficients is investigated close to the smectic-A-nematic phase transition. A detailed analysis of the interplay between smectic order and plasmon resonance is performed, thus unveiling the capability of plasmonic liquid crystal to be used in optical devices.
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Affiliation(s)
- R S Silva
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
| | - P B de Melo
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
| | - L Omena
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
| | - A M Nunes
- Instituto de Química e Biotecnologia, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
| | - M G A da Silva
- Instituto de Química e Biotecnologia, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
| | - M R Meneghetti
- Instituto de Química e Biotecnologia, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
| | - I N de Oliveira
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
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23
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Highly Sensitive and Practical Detection of Plant Viruses via Electrical Impedance of Droplets on Textured Silicon-Based Devices. SENSORS 2016; 16:s16111946. [PMID: 27869726 PMCID: PMC5134605 DOI: 10.3390/s16111946] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 11/08/2016] [Accepted: 11/11/2016] [Indexed: 02/06/2023]
Abstract
Early diagnosis of plant virus infections before the disease symptoms appearance may represent a significant benefit in limiting disease spread by a prompt application of appropriate containment steps. We propose a label-free procedure applied on a device structure where the electrical signal transduction is evaluated via impedance spectroscopy techniques. The device consists of a droplet suspension embedding two representative purified plant viruses i.e., Tomato mosaic virus and Turnip yellow mosaic virus, put in contact with a highly hydrophobic plasma textured silicon surface. Results show a high sensitivity of the system towards the virus particles with an interestingly low detection limit, from tens to hundreds of attomolar corresponding to pg/mL of sap, which refers, in the infection time-scale, to a concentration of virus particles in still-symptomless plants. Such a threshold limit, together with an envisaged engineering of an easily manageable device, compared to more sophisticated apparatuses, may contribute in simplifying the in-field plant virus diagnostics.
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24
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Sheetah GH, Liu Q, Smalyukh II. Self-assembly of predesigned optical materials in nematic codispersions of plasmonic nanorods. OPTICS LETTERS 2016; 41:4899-4902. [PMID: 27805645 DOI: 10.1364/ol.41.004899] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Optical metamaterials and other nanostructured metal-dielectric composites hold great potential for designing and practically realizing novel types of light-matter interactions. Here we develop an approach to fabricate composites with tunable pre-engineered properties via self-assembly of anisotropic nanoparticles codispersed in a nematic liquid crystal host. Orientations of plasmonic nanorods of varying aspect ratios are controlled to align parallel or perpendicular to the nematic director and retain this relative orientation during a facile electric switching. The ensuing dynamic reconfigurability of the surface plasmon resonances of a composite enables a previously inaccessible means of controlling light and may enable tunable plasmonic filters and polarizers.
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25
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Hauser AW, Liu D, Bryson KC, Hayward RC, Broer DJ. Reconfiguring Nanocomposite Liquid Crystal Polymer Films with Visible Light. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00165] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Adam W. Hauser
- Department of Polymer Science & Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | | | - Kyle C. Bryson
- Department of Polymer Science & Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Ryan C. Hayward
- Department of Polymer Science & Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
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26
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27
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de Oliveira EJL, de Oliveira IN, Lyra ML, Mirantsev LV. Tunable topological valence in nematic shells on spherocylindrical colloidal particles. Phys Rev E 2016; 93:012703. [PMID: 26871131 DOI: 10.1103/physreve.93.012703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Indexed: 06/05/2023]
Abstract
We perform molecular dynamics simulations of the orientational ordering on nematic shells delimited by spherocylindrical nanoscopic colloidal particles. We show that under conditions of degenerate planar anchoring, the equilibrium director field structure in these shells exhibits pairs of +1/2 topological defects at the poles of spherical cups in the absence of an external electric field. In addition, a certain number of pairs of ±1/2 defects occurs on the spherical cups far from the poles, thus resulting in a total of eight valence spots. A strong field applied along the main spherocylindrical axis removes the ±1/2 defect pairs while it coalesces the polar ones into a single +1 topological defect. A strong transverse field destroys all defects on the spherical cups but generates four +1/2 defects in the cylindrical part. Therefore, an external field can be used to control the number of valence centers in spherocylindrical nematic shells, thus unveiling their capability of acting as multivalent building blocks for nanophotonic devices.
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Affiliation(s)
- E J L de Oliveira
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió-Alagoas, Brazil
| | - I N de Oliveira
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió-Alagoas, Brazil
| | - M L Lyra
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió-Alagoas, Brazil
| | - L V Mirantsev
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió-Alagoas, Brazil
- Institute for Problems of Mechanical Engineering, Russian Academy of Sciences, St. Petersburg, Russia
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28
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Ackerman PJ, Mundoor H, Smalyukh II, van de Lagemaat J. Plasmon-Exciton Interactions Probed Using Spatial Coentrapment of Nanoparticles by Topological Singularities. ACS NANO 2015; 9:12392-400. [PMID: 26567626 DOI: 10.1021/acsnano.5b05715] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We study plasmon-exciton interaction by using topological singularities to spatially confine, selectively deliver, cotrap and optically probe colloidal semiconductor and plasmonic nanoparticles. The interaction is monitored in a single quantum system in the bulk of a liquid crystal medium where nanoparticles are manipulated and nanoconfined far from dielectric interfaces using laser tweezers and topological configurations containing singularities. When quantum dot-in-a-rod particles are spatially colocated with a plasmonic gold nanoburst particle in a topological singularity core, its fluorescence increases because blinking is significantly suppressed and the radiative decay rate increases by nearly an order of magnitude owing to the Purcell effect. We argue that the blinking suppression is the result of the radiative rate change that mitigates Auger recombination and quantum dot ionization, consequently reducing nonradiative recombination. Our work demonstrates that topological singularities are an effective platform for studying and controlling plasmon-exciton interactions.
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Affiliation(s)
- Paul J Ackerman
- Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
- Department of Electrical, Computer and Energy Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Haridas Mundoor
- Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
- Department of Electrical, Computer and Energy Engineering, University of Colorado , Boulder, Colorado 80309, United States
- Liquid Crystal Materials Research Center and Materials Science and Engineering Program, University of Colorado , Boulder, Colorado 80309, United States
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado , Boulder, Colorado 80309, United States
| | - Jao van de Lagemaat
- Department of Physics, University of Colorado , Boulder, Colorado 80309, United States
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado , Boulder, Colorado 80309, United States
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29
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Yuan Y, Smalyukh II. Topological nanocolloids with facile electric switching of plasmonic properties. OPTICS LETTERS 2015; 40:5630-5633. [PMID: 26625068 DOI: 10.1364/ol.40.005630] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Combining topology and plasmonics paradigms in nanocolloidal systems may enable new means of pre-engineering desired composite material properties. Here we design and realize orientationally ordered assemblies of noble metal nanoparticles with genus-one topology and unusual long-range ordering mediated by their interactions with the surrounding nematic fluid host. Facile electric switching of these composites is reminiscent of that of pristine liquid crystals (LCs), but provides a means of reconfiguring the nanoparticle assembly and thus also the ensuing composite medium's optical properties. Our findings may lead to formation of new molecular-colloidal soft matter phases with unusual optical properties, as well as optical metamaterials.
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30
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Duchesne I, Rainville S, Galstian T. Bacterial Motility Reveals Unknown Molecular Organization. Biophys J 2015; 109:2137-47. [PMID: 26588572 PMCID: PMC4656883 DOI: 10.1016/j.bpj.2015.09.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 09/17/2015] [Accepted: 09/21/2015] [Indexed: 10/22/2022] Open
Abstract
The water solubility of lyotropic liquid crystals (LCs) makes them very attractive to study the behavior of biological microorganisms in an environment where local symmetry is broken (as often encountered in nature). Several recent studies have shown a dramatic change in the behavior of flagellated bacteria when swimming in solutions of the lyotropic LC disodium cromoglycate (DSCG). In this study, the movements of Escherichia coli bacteria in DSCG-water solutions of different concentrations are observed to improve our understanding of this phenomenon. In addition, the viscosity of DSCG aqueous solutions is measured as a function of concentration at room temperature. We also experimentally identify a previously undescribed isotropic pretransition zone where bacteria start sticking to each other and to surfaces. Simple estimations show that the unbalanced osmotic pressure induced depletion force might be responsible for this sticking phenomenon. An estimate of the bacteria propulsive force and the DSCG aggregates length (versus concentration) are calculated from the measured viscosity of the medium. All these quantities are found to undergo a strong increase in the pretransition zone, starting at a threshold concentration of 6±1 wt % DSCG that is well below the known isotropic-LC transition (∼10 wt %). This study also shines light on the motility of flagellated bacteria in realistic environments, and it opens new avenues for interesting applications such as the use of motile microorganisms to probe the physical properties of their host or smart bandages that could guide bacteria out of wounds.
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Affiliation(s)
- Ismaël Duchesne
- Department of Physics, Engineering Physics and Optics and Center for Optics, Photonics and Lasers, Laval University, Quebec City, Quebec, Canada
| | - Simon Rainville
- Department of Physics, Engineering Physics and Optics and Center for Optics, Photonics and Lasers, Laval University, Quebec City, Quebec, Canada.
| | - Tigran Galstian
- Department of Physics, Engineering Physics and Optics and Center for Optics, Photonics and Lasers, Laval University, Quebec City, Quebec, Canada
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31
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de Melo PB, Nunes AM, Omena L, do Nascimento SMS, da Silva MGA, Meneghetti MR, de Oliveira IN. Thermo-optical properties and nonlinear optical response of smectic liquid crystals containing gold nanoparticles. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:042504. [PMID: 26565262 DOI: 10.1103/physreve.92.042504] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Indexed: 06/05/2023]
Abstract
The present work is devoted to the study of the thermo-optical and nonlinear optical properties of smectic samples containing gold nanoparticles with different shapes. By using the time-resolved Z-scan technique, we determine the effects of nanoparticle addition on the critical behavior of the thermal diffusivity and thermo-optical coefficient at the vicinity of the smectic-A-nematic phase transition. Our results reveal that introduction of gold nanoparticles affects the temperature dependence of thermo-optical parameters, due to the local distortions in the orientational order and heat generation provided by guest particles during the laser exposure. Further, we show that a nonlinear optical response may take place at temperatures where the smectic order is well established. We provide a detailed discussion of the effects associated with the introduction gold nanoparticles on the mechanisms behind the thermal transport and optical nonlinearity in liquid-crystal samples.
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Affiliation(s)
- P B de Melo
- Instituto de Física, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil
| | - A M Nunes
- Instituto de Química e Biotecnologia, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil
| | - L Omena
- Instituto de Física, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil
| | - S M S do Nascimento
- Instituto de Física, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil
| | - M G A da Silva
- Instituto de Química e Biotecnologia, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil
| | - M R Meneghetti
- Instituto de Química e Biotecnologia, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil
| | - I N de Oliveira
- Instituto de Física, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil
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Kim MJ, Cho HW, Kim J, Kim H, Sung BJ. Translational and rotational diffusion of a single nanorod in unentangled polymer melts. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:042601. [PMID: 26565264 DOI: 10.1103/physreve.92.042601] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Indexed: 06/05/2023]
Abstract
Polymer nanocomposites have been an issue of both academic and industrial interest due to promising electrical, mechanical, optical, and magnetic properties. The dynamics of nanoparticles in polymer nanocomposites is a key to understanding those properties of polymer nanocomposites and is important for applications such as self-healing nanocomposites. In this article we investigate the translational and the rotational dynamics of a single nanorod in unentangled polymer melts by employing extensive molecular dynamics simulations. A nanorod and polymers are modeled as semiflexible tangent chains of spherical beads. The stiffness of a nanorod is tuned by changing the bending potential between chemical bonds. When polymers are sufficiently long and the nanorod is stiff, the nanorod translates in an anisotropic fashion along the nanorod axis within time scales of translational relaxation times even in unentangled polymer melts. The rotational diffusion is suppressed more significantly than the translational diffusion as the polymer chain length is increased, thus the translational and rotational diffusion of the nanorod are decoupled. We also estimate the winding numbers of polymers, i.e., how many times a polymer winds the nanorod. The winding number increases with longer polymers but is relatively insensitive to the nanorod stiffness.
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Affiliation(s)
- Min Jung Kim
- Department of Chemistry and Research Institute for Basic Science, Sogang University, Seoul 121-742, Republic of Korea
| | - Hyun Woo Cho
- Department of Chemistry and Research Institute for Basic Science, Sogang University, Seoul 121-742, Republic of Korea
| | - Jeongmin Kim
- Department of Chemistry and Research Institute for Basic Science, Sogang University, Seoul 121-742, Republic of Korea
| | - Heesuk Kim
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791, South Korea
| | - Bong June Sung
- Department of Chemistry and Research Institute for Basic Science, Sogang University, Seoul 121-742, Republic of Korea
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Chen K, Metcalf LP, Rivas DP, Reich DH, Leheny RL. Anisotropic colloidal transport and periodic stick-slip motion in cholesteric finger textures. SOFT MATTER 2015; 11:4189-4196. [PMID: 25875803 DOI: 10.1039/c5sm00300h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have investigated the mobility of discoidal colloidal particles sedimenting within cholesteric finger textures formed by mixtures of the nematic liquid crystal 4-cyano-4'-pentylbiphenyl (5CB) and the chiral dopant 4-(2-methylbutyl)-4'-cyanobiphenyl (CB15) with cholesteric pitch p between 24 and 114 μm. The nickel disks, with radius 17 μm and thickness 300 nm, displayed varied transport behavior that depended on the size of the pitch and the orientation of the gravitational force with respect to the cholesteric axis. In textures with small pitch (p < 40 μm), the disks moved perpendicular to the axis irrespective of the orientation of gravity as a result of an elastic retarding force that prevented motion along the axis. In textures with larger pitch, the disks similarly moved perpendicular to the axis when the angle between the force and axis was large. When the angle was small, the disks displayed stick-slip motion caused by periodic yielding of the finger texture. A model considering viscous drag on the particles and the elastic energy cost of deforming the finger texture describes the stick-slip motion accurately. The effective drag viscosities obtained from the disk motion are anomalously large compared with those of pure nematic 5CB indicating a large contribution to the dissipation from the motion of disclinations in the texture in the vicinity of the translating disks.
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Affiliation(s)
- Kui Chen
- Department of Physics & Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
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Ryzhkova AV, Škarabot M, Muševič I. Surface charge and interactions of 20-nm nanocolloids in a nematic liquid crystal. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:042505. [PMID: 25974514 DOI: 10.1103/physreve.91.042505] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Indexed: 06/04/2023]
Abstract
We studied real-time motion of individual 20-nm silica nanoparticles in a thin layer of a nematic liquid crystal using a dark-field optical videomicroscopy. By tracking the positions of individual nanoparticles we observed that particle pair interactions are not only mediated by strong thermal fluctuations of the nematic liquid crystal, but also with a repulsive force of electric origin. We determined the total electric charge of silanated silica particles in the nematic liquid crystal 5CB by observing the electric-force-driven drift. Surprisingly, the surface electric charge density depends on colloidal size and is ∼4.5×10(-3)C/m(2) for 20-nm nanocolloids, and two orders of magnitude lower, i.e., ∼2.3×10(-5)C/m(2), for 1-μm colloids. We conclude that electrostatic repulsion between like-charged particles prevents the formation of permanent colloidal assemblies of nanometer size. We also observed strong attraction of 20-nm silica nanoparticles to confining polyimide surfaces and larger clusters, which gradually results in complete expulsion of nanoparticles from the nematic liquid crystal to the surfaces of the confining cell.
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Affiliation(s)
- A V Ryzhkova
- Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Electrical Engineering Technologies Laboratory, Department of Physics, South Ural State University, Lenina ave.76, 454080 Chelyabinsk, Russia
| | - M Škarabot
- Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - I Muševič
- Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
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35
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Zhang Y, Liu Q, Mundoor H, Yuan Y, Smalyukh II. Metal nanoparticle dispersion, alignment, and assembly in nematic liquid crystals for applications in switchable plasmonic color filters and E-polarizers. ACS NANO 2015; 9:3097-108. [PMID: 25712232 DOI: 10.1021/nn5074644] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Viewing angle characteristics of displays and performance of electro-optic devices are often compromised by the quality of dichroic thin-film polarizers, while dichroic optical filters usually lack tunability and cannot work beyond the visible part of optical spectrum. We demonstrate that molecular-colloidal organic-inorganic composites formed by liquid crystals and relatively dilute dispersions of orientationally ordered anisotropic gold nanoparticles, such as rods and platelets, can be used in engineering of switchable plasmonic polarizers and color filters. The use of metal nanoparticles instead of dichroic dyes allows for obtaining desired polarizing or scattering and absorption properties not only within the visible but also in the infrared parts of an optical spectrum. We explore spontaneous surface-anchoring-mediated alignment of surface-functionalized anisotropic gold nanoparticles and its control by low-voltage electric fields, elastic colloidal interactions and self-assembly, as well as the uses of these effects in defining tunable properties of the ensuing organic-inorganic nanostructured composites. Electrically tunable interaction of the composites may allow for engineering of practical electro-optic devices, such as a new breed of color filters and plasmonic polarizers.
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Affiliation(s)
- Yuan Zhang
- †Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
- ‡Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Qingkun Liu
- †Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
| | - Haridas Mundoor
- †Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
| | - Ye Yuan
- †Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
| | - Ivan I Smalyukh
- †Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
- §Department of Electrical, Computer, and Energy Engineering, Liquid Crystal Materials Research Center, and Materials Science Engineering Program, University of Colorado, Boulder, Colorado 80309, United States
- ⊥Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, United States
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Sokolov A, Zhou S, Lavrentovich OD, Aranson IS. Individual behavior and pairwise interactions between microswimmers in anisotropic liquid. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:013009. [PMID: 25679710 DOI: 10.1103/physreve.91.013009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Indexed: 06/04/2023]
Abstract
A motile bacterium swims by generating flow in its surrounding liquid. Anisotropy of the suspending liquid significantly modifies the swimming dynamics and corresponding flow signatures of an individual bacterium and impacts collective behavior. We study the interactions between swimming bacteria in an anisotropic environment exemplified by lyotropic chromonic liquid crystal. Our analysis reveals a significant localization of the bacteria-induced flow along a line coaxial with the bacterial body, which is due to strong viscosity anisotropy of the liquid crystal. Despite the fact that the average viscosity of the liquid crystal is two to three orders of magnitude higher than the viscosity of pure water, the speed of bacteria in the liquid crystal is of the same order of magnitude as in water. We show that bacteria can transport a cargo (a fluorescent particle) along a predetermined trajectory defined by the direction of molecular orientation of the liquid crystal. We demonstrate that while the hydrodynamic interaction between flagella of two close-by bacteria is negligible, the observed convergence of the swimming speeds as well as flagella waves' phase velocities may occur due to viscoelastic interaction between the bacterial bodies.
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Affiliation(s)
- Andrey Sokolov
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Shuang Zhou
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA
| | - Oleg D Lavrentovich
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA
| | - Igor S Aranson
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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Varney MCM, Zhang Q, Tasinkevych M, Silvestre NM, Bertness KA, Smalyukh II. Periodic dynamics, localization metastability, and elastic interaction of colloidal particles with confining surfaces and helicoidal structure of cholesteric liquid crystals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:062502. [PMID: 25615114 DOI: 10.1103/physreve.90.062502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Indexed: 06/04/2023]
Abstract
Nematic and cholesteric liquid crystals are three-dimensional fluids that possess long-range orientational ordering and can support both topological defects and chiral superstructures. Implications of this ordering remain unexplored even for simple dynamic processes such as the ones found in so-called "fall experiments," or motion of a spherical inclusion under the effects of gravity. Here we show that elastic and surface anchoring interactions prompt periodic dynamics of colloidal microparticles in confined cholesterics when gravity acts along the helical axis. We explore elastic interactions between colloidal microparticles and confining surfaces as well as with an aligned ground-state helical structure of cholesterics for different sizes of spheres relative to the cholesteric pitch, demonstrating unexpected departures from Stokes-like behavior at very low Reynolds numbers. We characterize metastable localization of microspheres under the effects of elastic and surface anchoring periodic potential landscapes seen by moving spheres, demonstrating the important roles played by anchoring memory, confinement, and topological defect transformation. These experimental findings are consistent with the results of numerical modeling performed through minimizing the total free energy due to colloidal inclusions at different locations along the helical axis and with respect to the confining substrates. A potential application emerging from this work is colloidal sorting based on particle shapes and sizes.
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Affiliation(s)
- Michael C M Varney
- Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Qiaoxuan Zhang
- Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA and Materials Science and Engineering Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Mykola Tasinkevych
- Max-Planck-Institut für Intelligente Systeme, D-70569 Stuttgart, Germany and Institut für Theoretische Physik IV, Universität Stuttgart, D-70569 Stuttgart, Germany
| | - Nuno M Silvestre
- Centro de Física Teórica e Computacional and Faculdade de Ciências da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa, Portugal
| | - Kris A Bertness
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Ivan I Smalyukh
- Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA and Materials Science and Engineering Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA and Department of Electrical, Computer, and Energy Engineering and Liquid Crystals Materials Research Center, University of Colorado at Boulder, Boulder, Colorado 80309, USA and Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado at Boulder, Boulder, Colorado 80309, USA
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38
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Senyuk B, Varney MCM, Lopez JA, Wang S, Wu N, Smalyukh II. Magnetically responsive gourd-shaped colloidal particles in cholesteric liquid crystals. SOFT MATTER 2014; 10:6014-6023. [PMID: 24994521 DOI: 10.1039/c4sm00878b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Particle shape and medium chirality are two key features recently used to control anisotropic colloidal self-assembly and dynamics in liquid crystals. Here, we study magnetically responsive gourd-shaped colloidal particles dispersed in cholesteric liquid crystals with periodicity comparable or smaller than the particle's dimensions. Using magnetic manipulation and optical tweezers, which allow one to position colloids near the confining walls, we measured the elastic repulsive interactions of these particles with confining surfaces and found that separation-dependent particle-wall interaction force is a non-monotonic function of separation and shows oscillatory behavior. We show that gourd-shaped particles in cholesterics reside not on a single sedimentation level, but on multiple long-lived metastable levels separated by a distance comparable to cholesteric periodicity. Finally, we demonstrate three-dimensional laser tweezers assisted assembly of gourd-shaped particles taking advantage of both orientational order and twist periodicity of cholesterics, potentially allowing new forms of orientationally and positionally ordered colloidal organization in these media.
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Affiliation(s)
- Bohdan Senyuk
- Department of Physics, University of Colorado, Boulder, CO 80309, USA.
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Hirankittiwong P, Chattham N, Limtrakul J, Haba O, Yonetake K, Eremin A, Stannarius R, Takezoe H. Optical manipulation of the nematic director field around microspheres covered with an azo-dendrimer monolayer. OPTICS EXPRESS 2014; 22:20087-20093. [PMID: 25321218 DOI: 10.1364/oe.22.020087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report here the optical manipulation of the director and topological defect structures of nematic liquid crystals around a silica microparticle with azobenzene-containing dendrimers (azo-dendrimers) on its surface. We successfully demonstrate the successive switching processes from hedgehog, to boojum, and further to Saturn ring configurations by ultraviolet (UV) light irradiation and termination. The switching time between these defect structures depends on the UV light intensity and attains about 50 ms. Since the pretreatment of microparticles is not necessary and the surface modification is spontaneously performed just by dissolving the azo-dendrimers in liquid crystals, this dendrimer supplies us with a variety of possible applications.
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