1
|
Pawale T, Yi S, Wang X, Zhang R, Li X. The fate of liquid crystal topological defects on chemically patterned surfaces during phase transitions. SOFT MATTER 2022; 18:5939-5948. [PMID: 35861160 DOI: 10.1039/d2sm00566b] [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
Controlling topological defects in liquid crystals (LCs) is an essential element in the development of areas such as directed self-assembly and micropatterning materials. However, during the phase transition on confined patterned surfaces, how the morphologies in one liquid crystalline phase change from deformations or defects into another phase is much less known. Here, we examine the fate of defects in a LC confined on a patterned surface during smectic-A-nematic and nematic-isotropic phase transitions, using experiments and simulation analyses. Upon heating from smectic-A to nematic, a Toric focal conical domain (TFCD) melts into a +1 converging boojum defect, which then transitioned into a concentric configuration as temperature increases, attributed to a steeper decrease of the bend and twist modulus compared to splay modulus. During cooling, TFCDs are developed from two distinct pathways depending on the cooling rates. Our continuum simulation recapitulates these transformations and provides elastic constant-based explanations for the two pathways. Although the phase transition pathways of defects are independent of the geometry of the confined patterns, the arrangement of FCDs is highly dependent on the size and shape of the patterns. Taken together, this simple approach offers promising opportunities for tuning the micro- or nano-patterning of topological defects in liquid crystals.
Collapse
Affiliation(s)
- Tejal Pawale
- Materials Science and Engineering Department, University of North Texas, Denton, USA.
| | - Shengzhu Yi
- Department of Physics, The Hongkong University of Science and Technology, Hongkong, China.
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiaowei Wang
- Materials Science and Engineering Department, University of North Texas, Denton, USA.
| | - Rui Zhang
- Department of Physics, The Hongkong University of Science and Technology, Hongkong, China.
| | - Xiao Li
- Materials Science and Engineering Department, University of North Texas, Denton, USA.
| |
Collapse
|
2
|
Boniello G, Vilchez V, Garre E, Mondiot F. Making Smectic Defect Patterns Electrically Reversible and Dynamically Tunable Using In Situ Polymer-Templated Nematic Liquid Crystals. Macromol Rapid Commun 2021; 42:e2100087. [PMID: 33876523 DOI: 10.1002/marc.202100087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/29/2021] [Indexed: 11/08/2022]
Abstract
Shaping liquid crystals (LCs) into arrays of defect patterns enables the design of composite materials with new stimuli-responsive properties. Self-assembled defect assemblies that may arise in layered smectic A (SmA) LCs such as focal conic domains (FCDs), exhibit remarkable optical features and abilities for ordering nanoparticles. However, such SmA defect patterns are essentially electrically irreversible, which currently limits their adjustability in a dynamic way. Here, in situ polymerization of the texture of SmA FCDs allows transferring them into more electrically responsive LC phases, such as nematic, making possible a dynamic switch between different textural and optical states of FCDs in a reversible manner with voltage. Moreover, the method readily enables to program the operating temperature range of the polymer/LC composite from its chemical composition, adapting the system to various potential uses. This approach may increment new applications of SmA defect patterns such as voltage-tunable privacy layers and may further inspire the design of LC-based nanostructured composite and hybrid materials with new functions that can be dynamically tuned with voltage.
Collapse
Affiliation(s)
- Giuseppe Boniello
- Surface du Verre et Interfaces, UMR 125, CNRS/Saint-Gobain, 39, quai Lucien Lefranc, Aubervilliers, Cedex F-93303, France
| | - Victoria Vilchez
- Surface du Verre et Interfaces, UMR 125, CNRS/Saint-Gobain, 39, quai Lucien Lefranc, Aubervilliers, Cedex F-93303, France
| | - Emmanuel Garre
- Surface du Verre et Interfaces, UMR 125, CNRS/Saint-Gobain, 39, quai Lucien Lefranc, Aubervilliers, Cedex F-93303, France
| | - Frédéric Mondiot
- Surface du Verre et Interfaces, UMR 125, CNRS/Saint-Gobain, 39, quai Lucien Lefranc, Aubervilliers, Cedex F-93303, France
| |
Collapse
|
3
|
Role of Stimuli on Liquid Crystalline Defects: From Defect Engineering to Switchable Functional Materials. MATERIALS 2020; 13:ma13235466. [PMID: 33266312 PMCID: PMC7729749 DOI: 10.3390/ma13235466] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 11/27/2020] [Accepted: 11/27/2020] [Indexed: 11/17/2022]
Abstract
Achieving tunable physical properties is currently one of the most exciting research topics. In order to realize this goal, a medium that is responsive to external stimuli and can undergo a change in its physical property is required. Liquid crystal (LC) is a prominent candidate, as its physical and optical properties can be easily manipulated with various stimuli, such as surface anchoring, rubbing, geometric confinement, and external fields. Having broken away from the past devotion to obtaining a uniform domain of LCs, people are now putting significant efforts toward forming and manipulating ordered and oriented defect structures with a unique arrangement within. The complicated molecular order with tunability would benefit the interdisciplinary research fields of optics, physics, photonics, and materials science. In this review, the recent progress toward defect engineering in the nematic and smectic phases by controlling the surface environment and electric field and their combinational methods is introduced. We close the review with a discussion of the possible applications enabled using LC defect structures as switchable materials.
Collapse
|
4
|
Preusse RS, George ER, Aghvami SA, Otchy TM, Gharbi MA. Hierarchical assembly of smectic liquid crystal defects at undulated interfaces. SOFT MATTER 2020; 16:8352-8358. [PMID: 32785413 DOI: 10.1039/d0sm01112f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The assembly of topological defects in liquid crystals has drawn significant interest in the last decade due to their ability to trap colloidal objects and direct their arrangements. They have also brought about a high impact in modern technologies, in particular in optics, e.g., microlens arrays, soft lithography templates, and optically selective masks. Here we study the formation of defects in smectic A liquid crystal with hybrid texture at undulated surfaces. We investigate the role of surface topography on the organization of focal conic domains (FCDs) in smectic films. We demonstrate new methods for assembling FCDs and disclinations into hierarchical structures. When the liquid crystal is heated to the nematic phase, we observe stable defect lines forming at specific locations. These defects are created to satisfy anchoring conditions and the geometry of confinement imposed by the boundaries. Once the liquid crystal is cooled to the smectic A phase, the disclinations maintain their positions, but periodic structures of reversible FCDs facing opposite directions arise between them. We report the correlation between the size of these FCDs and their eccentricities with the morphology of the interface. This work paves the way for creating new procedures to control the assembly of functional nanomaterials into tunable assemblies that may find relevance in the field of energy technology including in optoelectronic and photonic applications.
Collapse
Affiliation(s)
- Ryan S Preusse
- Department of Physics, University of Massachusetts Boston, Boston, MA 02125, USA.
| | - Elizabeth R George
- Department of Physics, University of Massachusetts Boston, Boston, MA 02125, USA.
| | - S Ali Aghvami
- Department of Biology and Neurophotonics Center, Boston University, Boston, MA 02215, USA
| | - Timothy M Otchy
- Department of Physics, Brandeis University, Waltham, MA 02453, USA
| | - Mohamed Amine Gharbi
- Department of Physics, University of Massachusetts Boston, Boston, MA 02125, USA.
| |
Collapse
|
5
|
Lee JS, Lee B, Song JK. A self-assembled nanoparticle cluster array fabricated using nematic-isotropic phase separation on a functionalized surface. SOFT MATTER 2019; 15:6696-6702. [PMID: 31380879 DOI: 10.1039/c9sm01150a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The manipulation of a large number of nanoparticles (NPs) is an interesting but challenging task. Here, we demonstrate a new method to fabricate an NP cluster array, in which the shape and size of each NP cluster can be controlled. The method involves the use of the solubility contrast of NPs in the isotropic and nematic liquid crystal (LC) media, and the isotropic-preference difference depending on the types of the surfaces. The former mechanism is used to trap NPs within the isotropic domain, the size of which is simply manipulated by adjusting temperature. The latter mechanism is used to control the location of isotropic pockets in the continuous nematic phase. By controlling the volume and location of the isotropic pocket, one can simply create various types of NP cluster arrays. This method does not involve the use of any external field, and may be applicable to other types of NPs, including ferroelectric or ferromagnetic materials, thereby expanding its applicability.
Collapse
Affiliation(s)
- Jun-Seo Lee
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Seobu-ro 2066, Jangan-gu, Suwon, Gyeonggi-do, Republic of Korea.
| | | | | |
Collapse
|
6
|
Kwon K, Suh BL, Park K, Kim J, Jung HT. Ultra-dense (~20 Tdot/in 2) nanoparticle array from an ordered supramolecular dendrimer containing a metal precursor. Sci Rep 2019; 9:3885. [PMID: 30846732 PMCID: PMC6405949 DOI: 10.1038/s41598-019-40363-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 02/01/2019] [Indexed: 11/09/2022] Open
Abstract
The fabrication of an ultra-dense, highly periodic nanoparticle array from a soft template is one of the most important issues in the fields of material science and nanotechnology. To date, block copolymer (BCP) structures have been primarily used as templates for fabricating highly periodic nanoparticle arrays with high areal densities. Herein, we demonstrate for the first time the use of a supramolecular dendrimer assembly for the formation of a highly ordered nanoparticle array with a high areal density of ~20 Tdot/in2, four times larger than that of the currently reported BCP-based nanoparticle arrays. By the simple thermal annealing of a dendrimers containing a metal precursor between two flat, solid substrates, a hexagonal array of small gold nanoparticles (with a diameter of ~1.6 nm and center-to-center distance of ~5.3 nm), oriented normal to the bottom, was achieved. Density functional theory calculations demonstrated that the gold cation strongly bound to the head group of the dendrimer. This structure served as a building block for self-assembly into a stable cylindrical structure. We anticipate that this study will lead to the creation of a large family of supramolecular dendrimers that can be utilized as soft templates for creating periodic, ultra-dense nanoparticle arrays.
Collapse
Affiliation(s)
- Kiok Kwon
- National Research Laboratory for Organic Optoelectronic Materials, Department of Chemical and Biomolecular Engineering (BK-21 Plus), Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea
| | - Bong Lim Suh
- Department of Chemical and Biomolecular Engineering (BK-21 Plus), Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea
| | - Kangho Park
- National Research Laboratory for Organic Optoelectronic Materials, Department of Chemical and Biomolecular Engineering (BK-21 Plus), Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea
| | - Jihan Kim
- Department of Chemical and Biomolecular Engineering (BK-21 Plus), Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea.
| | - Hee-Tae Jung
- National Research Laboratory for Organic Optoelectronic Materials, Department of Chemical and Biomolecular Engineering (BK-21 Plus), Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea. .,KAIST Institute for Nanocentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Korea.
| |
Collapse
|
7
|
Ghosh S, Ramos L, Remita H. Swollen hexagonal liquid crystals as smart nanoreactors: implementation in materials chemistry for energy applications. NANOSCALE 2018; 10:5793-5819. [PMID: 29547217 DOI: 10.1039/c7nr08457a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Materials are the key roadblocks for the commercialization of energy conversion devices in fuel cells and solar cells. Significant research has focused on tuning the intrinsic properties of materials at the nanometer scale. The soft template mediated controlled fabrication of advanced nanostructured materials is attracting considerable interest due to the promising applications of these materials in catalysis and electrocatalysis. Swollen hexagonal lyotropic liquid crystals (SLCs) consist of oil-swollen surfactant-stabilized 1D, 2D or 3D nanometric assemblies regularly arranged in an aqueous solvent. Interestingly, the characteristic size of the SLCs can be controlled by adjusting the volume ratio of oil to water. The non-polar and/or polar compartments of the SLCs can be doped with guest molecules and used as nanoreactors for the synthesis of various metals (Pt, Pd, Au, etc.), conducting polymers and composite nanostructures with controlled size and shape. 1D, 2D and 3D mono- and bimetallic nanostructures of controlled composition and porosity can also be fabricated. These materials have demonstrated impressive enhancements of their electrochemical properties as compared to their bulk counterparts and have been identified as promising for further implementation in energy harvesting applications. In this review article, recent research materials are described regarding the development of functional materials with much improved performances for catalysis applications. This review addresses a brief overview of swollen hexagonal mesophases as nanoreactors, describes examples of nanostructured materials synthesized in these nanoreactors, shows several examples of the energy conversion applications in solar light harvesting, fuel cells etc. and also summarizes the associated reaction mechanisms developed in the recent literature for enhanced catalytic activity.
Collapse
Affiliation(s)
- Srabanti Ghosh
- Laboratoire de Chimie Physique, UMR 8000-CNRS, Université de Paris-Sud, Université Paris Saclay, 91405 Orsay, France.
| | - Laurence Ramos
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
| | - Hynd Remita
- Laboratoire de Chimie Physique, UMR 8000-CNRS, Université de Paris-Sud, Université Paris Saclay, 91405 Orsay, France. and CNRS, Laboratoire de Chimie Physique, UMR 8000, 91405 Orsay, France
| |
Collapse
|
8
|
Shin MJ, Gim MJ, Yoon DK. Directed Self-Assembly of Topological Defects of Liquid Crystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2551-2556. [PMID: 29368930 DOI: 10.1021/acs.langmuir.7b04216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
One of the alluring aspects of liquid crystals (LCs) is their readily controllable self-assembly behavior, leading to comprehension of complex topological structures and practical patterning applications. Here, we report on manipulating various kinds of topological defects by adopting an imprinted polymer-based soft microchannel that simultaneously imposes adjustable surface anchoring, confinement, and uniaxial alignment. Distinctive molecular orientation could be achieved by varying the surface anchoring conditions at the sidewall polymer and the rubbing directions on the bottom layer. On this pioneering platform, a common LC material, 8CB (4'-n-octyl-4-cyano-biphenyl), was placed where various topological defect domains were generated in a periodic arrangement. The experimental results showed that our platform can change the packing behavior and even the shape of topological defects by varying the rubbing condition. We believe that this facile tool to modulate surface boundary conditions combined with topographic confinement can open a way to use LC materials in potential optical and patterning applications.
Collapse
Affiliation(s)
- Min Jeong Shin
- Graduate School of Nanoscience and Technology and KINC and ‡Department of Chemistry, KAIST , Daejeon 34141, Korea
| | - Min-Jun Gim
- Graduate School of Nanoscience and Technology and KINC and ‡Department of Chemistry, KAIST , Daejeon 34141, Korea
| | - Dong Ki Yoon
- Graduate School of Nanoscience and Technology and KINC and ‡Department of Chemistry, KAIST , Daejeon 34141, Korea
| |
Collapse
|
9
|
Kurioz P, Kralj M, Murray BS, Rosenblatt C, Kralj S. Nematic topological defects positionally controlled by geometry and external fields. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:109-118. [PMID: 29441256 PMCID: PMC5789434 DOI: 10.3762/bjnano.9.13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 12/12/2017] [Indexed: 06/08/2023]
Abstract
Using a Landau-de Gennes approach, we study the impact of confinement topology, geometry and external fields on the spatial positioning of nematic topological defects (TDs). In quasi two-dimensional systems we demonstrate that a confinement-enforced total topological charge of m > 1/2 decays into elementary TDs bearing a charge of m = 1/2. These assemble close to the bounding substrate to enable essentially bulk-like uniform nematic ordering in the central part of a system. This effect is reminiscent of the Faraday cavity phenomenon in electrostatics. We observe that in certain confinement geometries, varying the correlation length size of the order parameter could trigger a global rotation of an assembly of TDs. Finally, we show that an external electric field could be used to drag the boojum fingertip towards the interior of the confinement cell. Assemblies of TDs could be exploited as traps for appropriate nanoparticles, opening several opportunities for the development of functional nanodevices.
Collapse
Affiliation(s)
- Pavlo Kurioz
- Jozef Stefan International Postgraduate School, Jamova 39 , 1000 Ljubljana, Slovenia
| | | | - Bryce S Murray
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, USA
| | - Charles Rosenblatt
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, USA
| | - Samo Kralj
- Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroska cesta 160, 2000 Maribor, Slovenia
- Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| |
Collapse
|