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Xu Y, Huang Z, Zhang Z, Ding B, Li P, Liu J, Hao Y, Dai L, Zhang H, Zhu C, Cai W, Liu B. An Electro-Optical Kerr Device Based on 2D Boron Nitride Liquid Crystals for Solar-Blind Communications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2307330. [PMID: 38497596 DOI: 10.1002/adma.202307330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 03/08/2024] [Indexed: 03/19/2024]
Abstract
Achieving light modulation in the spectral range of 200-280 nm is a prerequisite for solar-blind ultraviolet communication, where current technologies are mainly based on the electro-luminescent self-modulation of the ultraviolet source. External light modulation through the electro-birefringence control of liquid crystal (LC) devices has shown success in the visible-to-infrared regions. However, the poor stability of conventional LCs against ultraviolet irradiation and their weak electro-optical response make it challenging to modulate ultraviolet light. Here, an external ultraviolet light modulator is demonstrated using two-dimensional boron nitride LC. It exhibits robust ultraviolet stability and a record-high specific electro-optical Kerr coefficient of 5.1 × 10⁻2 m V-2, being three orders of magnitude higher than those of other known electro-optical media that are transparent (or potentially transparent) in the ultraviolent spectral range. The sensitive response enables fabricating transmissive and stable ultraviolet-C electro-optical Kerr modulators for solar-blind ultraviolet light. An M-ary coding array with high transmission density is also demonstrated for solar-blind ultraviolet communication.
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Affiliation(s)
- Youan Xu
- Xi'an Research Institute of High Technology, Xi'an, 710025, China
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Ziyang Huang
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Zehao Zhang
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Baofu Ding
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
- Institute of Technology for Carbon Neutrality/Faculty of Materials Science and Engineering, Shenzhen Institute of Advanced Technology, CAS, Shenzhen, 518055, China
| | - Peixuan Li
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Jiarong Liu
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Yugan Hao
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Lixin Dai
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Hao Zhang
- Institute of Low-dimensional Materials Genome Initiative, College of Chemistry and Environmental Engineering of Shenzhen University, Shenzhen, 518060, China
| | - Caizhen Zhu
- Institute of Low-dimensional Materials Genome Initiative, College of Chemistry and Environmental Engineering of Shenzhen University, Shenzhen, 518060, China
| | - Wei Cai
- Xi'an Research Institute of High Technology, Xi'an, 710025, China
| | - Bilu Liu
- Shenzhen Geim Graphene Center, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
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2
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Salgado-Blanco D, Díaz-Herrera E, Martínez-González JA, Mendoza CI. Phase transitions and topological defects in discotic liquid crystal droplets with planar anchoring: a Monte Carlo simulation study. SOFT MATTER 2023; 19:5916-5924. [PMID: 37485668 DOI: 10.1039/d3sm00534h] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
In this work we present the results of Monte Carlo (MC) simulations at the isothermal-isobaric ensemble for a discotic liquid crystal (DLC) droplet whose surface promotes edge-on (planar) anchoring. For a given pressure, we simulate an annealing process that enables observation of phase transitions within the spherical droplet. In particular, we report a first order isotropic-nematic transition as well as a nematic-columnar transition at the center of the droplet. We found the appearance of topological defects consisting of two disclination lines with ends at the surface of the sphere. We also observed that both transitions, isotropic-nematic and nematic-columnar, occur at lower temperatures as compared to the unconfined system.
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Affiliation(s)
- Daniel Salgado-Blanco
- División de Materiales Avanzados, IPICYT, Camino a la Presa San José 2055, 78216, San Luis Potosí, S. L. P. 78216, Mexico
- CONACyT - Centro Nacional de Supercómputo, IPICYT, Camino a la Presa San José 2055, 78216, San Luis Potosí, S. L. P. 78216, Mexico.
| | - Enrique Díaz-Herrera
- Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Ave. San Rafael Atlixco 186, Col. Vicentina, 09340 México, Ciudad de México, Mexico
| | - José A Martínez-González
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, Av. Parque Chapultepec 1570, San Luis Potosí, 78210 SLP, Mexico.
| | - Carlos I Mendoza
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apdo. Postal 70-360, 04510 México, Ciudad de México, Mexico
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3
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Abele CD, Giesselmann F. Dynamic light scattering analysis of size-selected graphene oxide 2D colloids fractioned via liquid crystal phase separation. SOFT MATTER 2022; 18:6607-6617. [PMID: 35997161 DOI: 10.1039/d2sm00662f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Exfoliated platelets of graphene oxide (GO) can be considered as polydisperse 2D colloids that form nematic colloidal liquid crystal phases in aqueous suspension even at very low concentrations thanks to their extremely high aspect ratios. However, with the rapidly emerging scientific interest in these GO-based liquid crystals, it became clear that the precise analysis and control of the GO sheet size distribution is essential, both for their scientific understanding and for potential applications, e.g., in optoelectronic devices, nanocomposites, or catalysis. In this work, we show that the mean effective (hydrodynamic) GO platelet width can be determined from the translational diffusion coefficient with depolarized dynamic light scattering by using a model for circular, infinitely thin disks. We further studied the phase separation process of biphasic isotropic-nematic GO dispersions and developed a simple fractionation protocol, which can be used to prepare relatively monodisperse fractions of GO sheets with widths ranging from 2.0-12.4 μm. Overall, we expect that the combined application of these relatively simple fractionation and analysis methods will advance the fabrication of well-defined and size-selected GO-based systems.
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Affiliation(s)
- Christina D Abele
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
| | - Frank Giesselmann
- Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany.
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4
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Salgado-Blanco D, Llanas-García AH, Díaz-Herrera E, Martínez-González JA, Mendoza CI. Structural properties and ring defect formation in discotic liquid crystal nanodroplets. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:254001. [PMID: 35358952 DOI: 10.1088/1361-648x/ac630b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
In this work, we performedNpTMonte Carlo simulations of a Gay-Berne discotic liquid crystal confined in a spherical droplet under face-on anchoring and fixed pressure. We find that, in contrast to the unbounded system, a plot of the order parameter as function of temperature does not show a clear evidence of a first-order isotropic-nematic transition. We also find that the impossibility of simultaneously satisfy the uniform director field requirement of a nematic phase with the radial boundary conditions, results in the appearance of a ring disclination line as a stress release mechanism in the interior of the droplet. Under further cooling, a columnar phase appears at the center of the droplet.
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Affiliation(s)
- Daniel Salgado-Blanco
- Cátedras CONACyT-Centro Nacional de Supercómputo, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, 78216, San Luis Potosí, México
- División de Materiales Avanzados, IPICYT, Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, S. L. P., 78216, México
| | - Andrea H Llanas-García
- División de Materiales Avanzados, IPICYT, Camino a la Presa San José 2055, Col. Lomas 4a Sección, San Luis Potosí, S. L. P., 78216, México
| | - Enrique Díaz-Herrera
- Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Ave. San Rafael Atlixco 186, Col. Vicentina, 09340 México, Ciudad de México, Mexico
| | - José A Martínez-González
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, Av. Parque Chapultepec 1570, San Luis Potosí 78210 SLP, Mexico
| | - Carlos I Mendoza
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apdo. Postal 70-360, 04510 México, Ciudad de México, Mexico
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Hribar Boštjančič P, Gregorin Ž, Sebastián N, Osterman N, Lisjak D, Mertelj A. Isotropic to nematic transition in alcohol ferrofluids of barium hexaferrite nanoplatelets. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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6
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Abstract
Colloidal self-assembly refers to a solution-processed assembly of nanometer-/micrometer-sized, well-dispersed particles into secondary structures, whose collective properties are controlled by not only nanoparticle property but also the superstructure symmetry, orientation, phase, and dimension. This combination of characteristics makes colloidal superstructures highly susceptible to remote stimuli or local environmental changes, representing a prominent platform for developing stimuli-responsive materials and smart devices. Chemists are achieving even more delicate control over their active responses to various practical stimuli, setting the stage ready for fully exploiting the potential of this unique set of materials. This review addresses the assembly of colloids into stimuli-responsive or smart nanostructured materials. We first delineate the colloidal self-assembly driven by forces of different length scales. A set of concepts and equations are outlined for controlling the colloidal crystal growth, appreciating the importance of particle connectivity in creating responsive superstructures. We then present working mechanisms and practical strategies for engineering smart colloidal assemblies. The concepts underpinning separation and connectivity control are systematically introduced, allowing active tuning and precise prediction of the colloidal crystal properties in response to external stimuli. Various exciting applications of these unique materials are summarized with a specific focus on the structure-property correlation in smart materials and functional devices. We conclude this review with a summary of existing challenges in colloidal self-assembly of smart materials and provide a perspective on their further advances to the next generation.
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Affiliation(s)
- Zhiwei Li
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Qingsong Fan
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Yadong Yin
- Department of Chemistry, University of California, Riverside, California 92521, United States
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7
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Chi E, Huang H, Zhang F, He T. Nematic Phase of Plate-like Semicrystalline Block Copolymer Single Crystals in Solution Studied by Small-Angle X-Ray Scattering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2397-2405. [PMID: 33560849 DOI: 10.1021/acs.langmuir.0c03370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Crystalline block copolymers have been used to prepare plate-like colloidal systems with well-controlled size, shape, and size distribution. The isotropic-to-nematic (I-N) phase transition of the novel plate-like colloidal particle suspensions has been reported previously. In this work, we focus on the characterization of the solution structure of the crystals and the N-phase using small- and ultrasmall-angle X-ray scattering techniques (SAXS/USAXS). The system has polystyrene-block-poly(l-lactide) (PS-b-PLLA) block copolymer single crystals (BCSCs) with different sizes dispersed in p-xylene. These crystals are truncated lozenge in shape and have effective diameters ranging from 550 to 4000 nm with a uniform dry thickness of 18.0 nm. Scattering of the individual crystal in solution can be simplified using a disc model with a core layer of 9-10 nm due to the lower contrast of the tethered PS layer. BCSC suspensions filled in thin quartz capillaries are prepared for monitoring the structural information. SAXS measurements of the isotropic phase show a strong face-to-face correlation, indicating that platelets form small stacked clusters in solutions. The isotropic phase is thus a coexistence of single crystals and the stacked multiple-layered clusters. The face-to-face spacing, d, in the N phases is around 75-90 nm, which increases slightly upon increasing the size of crystals. For a given system, the spacing does not change with increasing concentration under the current experimental conditions. Finally, the possible formation of lamellar domains within the N phase is also discussed due to the lateral attraction of this system. These results demonstrate the importance of the lateral attraction between the polar crystalline PLLA blocks on the formation of the N phase: the BCSCs self-assemble into larger sheets via the lateral attraction, which further enhances the I-N transition.
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Affiliation(s)
- Enyi Chi
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Haiying Huang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Fajun Zhang
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, Tübingen 72076, Germany
| | - Tianbai He
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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8
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H. Siboni N, Shrivastav GP, Klapp SHL. Non-monotonic response of a sheared magnetic liquid crystal to a continuously increasing external field. J Chem Phys 2020; 152:024505. [DOI: 10.1063/1.5126398] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Nima H. Siboni
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - Gaurav P. Shrivastav
- Institute für Theoretical Physics, Technische Universität Wien, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Sabine H. L. Klapp
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
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9
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Mizani S, Aliabadi R, Salehi H, Varga S. Orientational ordering and layering of hard plates in narrow slitlike pores. Phys Rev E 2019; 100:032704. [PMID: 31639981 DOI: 10.1103/physreve.100.032704] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Indexed: 11/07/2022]
Abstract
We examine the ordering behavior of hard platelike particles in a very narrow, slitlike pore using the Parsons-Lee density functional theory and the restricted orientation approximation. We observe that the plates are orientationally ordered and align perpendicularly (face-on) to the walls at low densities, a first-order layering transition occurs between uniaxial nematic structures having n and n+1 layers at intermediate densities, and even a phase transition between a monolayer with parallel (edge-on) orientational order and n layers with a perpendicular one can be detected at high densities. In addition to this, the edge-on monolayer is usually biaxial nematic, and a uniaxial-biaxial nematic phase transition can be also seen at very high densities.
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Affiliation(s)
- Sakine Mizani
- Department of Physics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Roohollah Aliabadi
- Department of Physics, Faculty of Science, Fasa University, 74617-81189 Fasa, Iran
| | - Hamdollah Salehi
- Department of Physics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Szabolcs Varga
- Institute of Physics and Mechatronics, University of Pannonia, P.O. Box 158, Veszprém H-8201, Hungary
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10
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Hogan BT, Kovalska E, Zhukova MO, Yildirim M, Baranov A, Craciun MF, Baldycheva A. 2D WS 2 liquid crystals: tunable functionality enabling diverse applications. NANOSCALE 2019; 11:16886-16895. [PMID: 31483415 DOI: 10.1039/c8nr07205a] [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 first observation of liquid crystalline dispersions of liquid phase-exfoliated tungsten disulfide flakes is reported in a range of organic solvents. The liquid crystals demonstrate significant birefringence as observed in the linear and circular dichroism measurements respectively. In particular, linear dichroism is observed throughout the visible range while broad-band circular dichroism can be observed in the range from 500-800 nm. Under an applied magnetic field of ±1.5 T the circular dichroism can be switched ON/OFF, while the wavelength range for switching can be tuned from large to narrow range by the proper selection of the host solvent. In combination with photoluminescence capabilities of WS2, this opens a pathway to a wide variety of applications, such as deposition of highly uniform films over large areas for photovoltaic and terahertz devices.
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11
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Abstract
Lyotropic liquid crystals from colloidal particles have been known for more than a century, but have attracted a revived interest over the last few years. This is due to the developments in nanoscience and nanotechnology, where the liquid crystal order can be exploited to orient and reorient the anisotropic colloids, thus enabling, increasing and switching the preferential properties of the nanoparticles. In particular, carbon-based colloids like carbon nanotubes and graphene/graphene–oxide have increasingly been studied with respect to their lyotropic liquid crystalline properties over the recent years. We critically review aspects of lyotropic graphene oxide liquid crystal with respect to properties and behavior which seem to be generally established, but also discuss those effects that are largely unfamiliar so far, or as of yet of controversial experimental or theoretical outcome.
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12
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Le Ferrand H, Bouville F, Studart AR. Design of textured multi-layered structures via magnetically assisted slip casting. SOFT MATTER 2019; 15:3886-3896. [PMID: 30984954 DOI: 10.1039/c9sm00390h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Multi-layered composites in nature often show functional properties that are determined by the specific orientation of inorganic building blocks within each layer. The shell of bivalve molluscs and the exoskeleton of crustaceans constitute prominent examples. An effective approach to artificially produce textured microstructures inspired by such complex composites is magnetically assisted slip casting (MASC). MASC is a colloidal process in which anisotropic particles are magnetically oriented at arbitrarily defined angles and collected at the surface of a porous mould to grow the material in an additive manner. Whereas a number of proof-of-concept studies have established the potential of the technique, the full design space available for MASC-fabricated structures, and the limits of the approach, have so far not been explored systematically. To fill this gap, we have studied both theoretically and experimentally the various torques that act on the particles at the different stages of the assembly process. We define the boundary conditions of the MASC process for magnetically responsive alumina platelets suspended in a low-viscosity aqueous suspension, considering the composition of the colloidal suspension and the dynamics of the particle alignment process under a rotating magnetic field. These findings lead to design guidelines for the fabrication of bio-inspired composites with customized multi-scale structures for a broad range of applications.
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Affiliation(s)
- Hortense Le Ferrand
- Complex Materials, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
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13
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Ugale AD, Chi L, Kim MK, Chae S, Choi JY, Yoo JB. Expanded graphene oxide fibers with high strength and increased elongation. RSC Adv 2019; 9:4198-4202. [PMID: 35520205 PMCID: PMC9060574 DOI: 10.1039/c8ra09464k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 01/02/2019] [Indexed: 11/21/2022] Open
Abstract
We report the role of chemically expanded graphite in the fabrication of high-performance graphene oxide fibers by wet spinning. X-ray diffraction peak showed that the interplanar distance of the expanded graphene oxide (EGO) fiber was more than that of graphene oxide (GO) fiber due to the expanded graphite. X-ray photon spectroscopy analysis revealed that EGO was more oxidized than GO. The hydrogen bonding network and secondary intermolecular interaction made the EGO aqueous solution more stable and crystalline, and it was able to be stretched in the coagulation bath. Morphological analysis showed the excellent alignment and compactness of EGO sheets in the fibers. The increased interplanar distance between the EGO sheets favored the edge-to-edge interaction more than the basal plane interaction within the fiber, thus resulting in high mechanical strength (492 MPa) and increased elongation (6.1%).
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Affiliation(s)
- Ashok D Ugale
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University Suwon 440-746 Republic of Korea
| | - LinLin Chi
- Advanced Materials Science and Engineering, Sungkyunkwan University Suwon 440-746 Republic of Korea
| | - Min-Kyu Kim
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University Suwon 440-746 Republic of Korea
| | - Sudong Chae
- Advanced Materials Science and Engineering, Sungkyunkwan University Suwon 440-746 Republic of Korea
| | - Jae-Young Choi
- Advanced Materials Science and Engineering, Sungkyunkwan University Suwon 440-746 Republic of Korea
| | - Ji-Beom Yoo
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University Suwon 440-746 Republic of Korea
- Advanced Materials Science and Engineering, Sungkyunkwan University Suwon 440-746 Republic of Korea
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14
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Wei Q, Wufuer A, Wang M, Wang Y, Dai L. Elastic three-dimensional graphene sponge fabricated by the liquid crystals of controlled large graphene oxide sheets. SN APPLIED SCIENCES 2019. [DOI: 10.1007/s42452-018-0062-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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15
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Experimental study on reversible formation of 2D flocs from plate-like particles dispersed in Newtonian fluid under torsional flow. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.03.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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16
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García ÁG, Tuinier R, Maring JV, Opdam J, Wensink HH, Lekkerkerker HNW. Depletion-driven four-phase coexistences in discotic systems. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1463471] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Álvaro González García
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology , Eindhoven, The Netherlands
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
| | - Remco Tuinier
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology , Eindhoven, The Netherlands
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
| | - Jasper V. Maring
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology , Eindhoven, The Netherlands
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
| | - Joeri Opdam
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology , Eindhoven, The Netherlands
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
| | - Henricus H. Wensink
- Laboratoire de Physique des Solides - UMR 8502, Université Paris-Sud, Université Paris-Saclay and CNRS , Orsay, France
| | - Henk N. W. Lekkerkerker
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry & Debye Institute, Utrecht University , Utrecht, The Netherlands
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17
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Leite Rubim R, Abrantes Barros M, Missègue T, Bougis K, Navailles L, Nallet F. Highly confined stacks of graphene oxide sheets in water. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:30. [PMID: 29546498 DOI: 10.1140/epje/i2018-11636-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 02/21/2018] [Indexed: 06/08/2023]
Abstract
Since the discovery of graphene oxide (GO), the most accessible of the precursors of graphene, this material has been widely studied for applications in science and technology. In this work, we describe a procedure to obtain GO dispersions in water at high concentrations, these highly dehydrated dispersions being in addition fully redispersible by dilution. With the availability of such concentrated samples, it was possible to investigate the structure of hydrated GO sheets in a previously unexplored range of concentrations, and to evidence a structural phase transition. Tentatively applying models designed for describing the small-angle scattering curve in the Smectic A (or [Formula: see text]) phase of lyotropic systems, it was possible to extract elastic parameters characterising the system on the dilute side of the transition, thereby evidencing the relevance of both electrostatic and steric (Helfrich) interactions in stabilising aqueous lamellar stacks of GO sheets.
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Affiliation(s)
- Rafael Leite Rubim
- Université de Bordeaux, Centre de recherche Paul-Pascal-CNRS, 115 avenue du Docteur-Schweitzer, F-33600, Pessac, France
| | - Margarida Abrantes Barros
- Université de Bordeaux, Centre de recherche Paul-Pascal-CNRS, 115 avenue du Docteur-Schweitzer, F-33600, Pessac, France
- Técnico Lisboa, Av. Rovisco Pais, 1, PT-1049-001, Lisboa, Portugal
| | - Thomas Missègue
- Université de Bordeaux, Centre de recherche Paul-Pascal-CNRS, 115 avenue du Docteur-Schweitzer, F-33600, Pessac, France
| | - Kévin Bougis
- Université de Bordeaux, Centre de recherche Paul-Pascal-CNRS, 115 avenue du Docteur-Schweitzer, F-33600, Pessac, France
| | - Laurence Navailles
- Université de Bordeaux, Centre de recherche Paul-Pascal-CNRS, 115 avenue du Docteur-Schweitzer, F-33600, Pessac, France
| | - Frédéric Nallet
- Université de Bordeaux, Centre de recherche Paul-Pascal-CNRS, 115 avenue du Docteur-Schweitzer, F-33600, Pessac, France.
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Zabet M, Trinh K, Toghiani H, Lacy TE, Pittman CU, Kundu S. Anisotropic Nanoparticles Contributing to Shear-Thickening Behavior of Fumed Silica Suspensions. ACS OMEGA 2017; 2:8877-8887. [PMID: 31457416 PMCID: PMC6645521 DOI: 10.1021/acsomega.7b01484] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 11/27/2017] [Indexed: 06/10/2023]
Abstract
Rheological characteristics of a concentrated suspension can be tuned using anisotropic particles having various shapes and sizes. Here, the role of anisotropic nanoparticles, such as surface-functionalized multiwall carbon nanotubes (MWNTs) and graphene oxide nanoplatelets (GONPs), on the rheological behavior of fumed silica suspensions in poly(ethylene glycol) (PEG) is investigated. In these mixed-particle suspensions, the concentrations of MWNTs and GONPs are much lower than the fumed silica concentration. The suspensions are stable, and hydrogen-bonded PEG solvation layers around the particles inhibit their flocculation. Fumed silica suspensions over the concentration range considered here display shear-thickening behavior. However, for a larger concentration of MWNTs and with increasing aspect ratios, the shear-thickening behavior diminishes. In contrast, a distinct shear-thickening response has been observed for the GONP-containing suspensions for similar mass fractions (MFs) of MWNTs. For these suspensions, shear thickening is achieved at a lower solid MFs compared to the suspensions consisting of only fumed silica. A significant weight reduction of shear-thickening fluids that can be achieved by this approach is beneficial for many applications. Our results provide guiding principles for controlling the rheological behavior of mixed-particle systems relevant in many fields.
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Affiliation(s)
- Mahla Zabet
- Dave
C. Swalm School of Chemical Engineering, Mechanical Engineering Department, Aerospace Engineering
Department, and Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Kevin Trinh
- Dave
C. Swalm School of Chemical Engineering, Mechanical Engineering Department, Aerospace Engineering
Department, and Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Hossein Toghiani
- Dave
C. Swalm School of Chemical Engineering, Mechanical Engineering Department, Aerospace Engineering
Department, and Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Thomas E. Lacy
- Dave
C. Swalm School of Chemical Engineering, Mechanical Engineering Department, Aerospace Engineering
Department, and Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Charles U. Pittman
- Dave
C. Swalm School of Chemical Engineering, Mechanical Engineering Department, Aerospace Engineering
Department, and Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Santanu Kundu
- Dave
C. Swalm School of Chemical Engineering, Mechanical Engineering Department, Aerospace Engineering
Department, and Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
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19
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Díaz-De Armas A, Martínez-Ratón Y. Role of length polydispersity in the phase behavior of freely rotating hard-rectangle fluids. Phys Rev E 2017; 95:052702. [PMID: 28618522 DOI: 10.1103/physreve.95.052702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Indexed: 11/07/2022]
Abstract
We use the density-functional formalism, in particular the scaled-particle theory, applied to a length-polydisperse hard-rectangle fluid to study its phase behavior as a function of the mean particle aspect ratio κ_{0} and polydispersity Δ_{0}. The numerical solutions of the coexistence equations are calculated by transforming the original problem with infinite degrees of freedoms to a finite set of equations for the amplitudes of the Fourier expansion of the moments of the density profiles. We divide the study into two parts. The first one is devoted to the calculation of the phase diagrams in the packing fraction η_{0}-κ_{0} plane for a fixed Δ_{0} and selecting parent distribution functions with exponential (the Schulz distribution) or Gaussian decays. In the second part we study the phase behavior in the η_{0}-Δ_{0} plane for fixed κ_{0} while Δ_{0} is changed. We characterize in detail the orientational ordering of particles and the fractionation of different species between the coexisting phases. Also we study the character (second vs first order) of the isotropic-nematic phase transition as a function of polydispersity. We particularly focus on the stability of the tetratic phase as a function of κ_{0} and Δ_{0}. The isotropic-nematic transition becomes strongly of first order when polydispersity is increased: The coexistence gap widens and the location of the tricritical point moves to higher values of κ_{0} while the tetratic phase is slightly destabilized with respect to the nematic one. The results obtained here can be tested in experiments on shaken monolayers of granular rods.
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Affiliation(s)
- Ariel Díaz-De Armas
- Grupo Interdisciplinar de Sistemas Complejos, Departamento de Matemáticas, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Leganés, Madrid, Spain
| | - Yuri Martínez-Ratón
- Grupo Interdisciplinar de Sistemas Complejos, Departamento de Matemáticas, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Leganés, Madrid, Spain
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20
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Chen F, Chen M, Chang YW, Lin P, Chen Y, Cheng Z. Polydispersity reduction of colloidal plates via size fractionation of the isotropic-nematic phase transition. SOFT MATTER 2017; 13:3789-3793. [PMID: 28480932 DOI: 10.1039/c7sm00476a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Controlling the size polydispersity of colloidal particles is important for their phase transitions, resulting structures, and properties. In this study, a fractionation method was established to control the polydispersity of colloidal plates based on the isotropic-nematic (I-N) phase transition. The size ratio of nanoplates between the N phase and the I phase (DN/DI) was relatively large, whereas the size polydispersities in both the N phase and the I phase were smaller than that of the original sample before fractionation. The degree of fractionation was dependent on the time since the phase transition began and the polydispersity of the original sample. A long time resulted in a small DN/DI and a small degree of polydispersity reduction. The experimental data confirmed a quadratic scaling of DN/DI with polydispersity that was predicted by simulations. Large to small particles were segregated sequentially by sedimentation because of self-assembly and gravity. The polydispersity reduction based on the I-N phase transition can be utilized to select nanoplates with a certain size with improved size monodispersity.
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Affiliation(s)
- Fang Chen
- Soft Matter Center, Guangdong Provincial Key Laboratory on Functional Soft Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou, 51006, China
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21
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Liu Y, Xu Z, Gao W, Cheng Z, Gao C. Graphene and Other 2D Colloids: Liquid Crystals and Macroscopic Fibers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1606794. [PMID: 28233348 DOI: 10.1002/adma.201606794] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 01/19/2017] [Indexed: 06/06/2023]
Abstract
Two-dimensional colloidal nanomaterials are running into renaissance after the enlightening researches of graphene. Macroscopic one-dimensional fiber is an optimal ordered structural form to express the in-plane merits of 2D nanomaterials, and the formation of liquid crystals (LCs) allows the creation of continuous fibers. In the correlated system from LCs to fibers, understanding their macroscopic organizing behavior and transforming them into new solid fibers is greatly significant for applications. Herein, we retrospect the history of 2D colloids and discuss about the concept of 2D nanomaterial fibers in the context of LCs, elaborating the motivation, principle and possible strategies of fabrication. Then we highlight the creation, development and typical applications of graphene fibers. Additionally, the latest advances of other 2D nanomaterial fibers are also summarized. Finally, conclusions, challenges and perspectives are provided to show great expectations of better and more fibrous materials of 2D nanomaterials. This review gives a comprehensive retrospect of the past century-long effort about the whole development of 2D colloids, and plots a clear roadmap - "lamellar solid - LCs - macroscopic fibers - flexible devices", which will certainly open a new era of structural-multifunctional application for the conventional 2D colloids.
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Affiliation(s)
- Yingjun Liu
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, P. R. China
| | - Zhen Xu
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, P. R. China
| | - Weiwei Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, P. R. China
| | - Zhengdong Cheng
- Arti McFerrin Department of Chemical Engineering and Department of Materials Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Chao Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, P. R. China
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22
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Ahmad RTM, Shen TZ, Masud AR, Ekanayaka TK, Lee B, Song JK. Guided Electro-Optical Switching of Small Graphene Oxide Particles by Larger Ones in Aqueous Dispersion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:13458-13463. [PMID: 27935312 DOI: 10.1021/acs.langmuir.6b03460] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Although the large Kerr coefficient of aqueous graphene oxide (GO) dispersions is quite attractive for electro-optical applications with low power consumption, the maximum birefringence of GO dispersions is not sufficiently high for actual display applications. Here we report that adding a small amount of larger GO particles (about 4 μm) into a high-concentration dispersion of small GO (about 0.2 μm) can improve the electro-optical sensitivity to an electric field and also the maximum birefringence. Large GOs induce the ordering of small particles and enhance the electro-optical switching. Large GOs have higher polarizability and are easily driven under an applied electric field, and the rotational motion of large GO particles leads to switching of surrounding small GO particles, improving the electro-optical performance. The binary mixture can overcome the limitations of pure dispersions of large GO or small GO particles; the former has high interparticle interaction, and the latter has low sensitivity to an electric field.
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Affiliation(s)
- Rana Tariq Mehmood Ahmad
- School of Electronic and Electrical Engineering, Sungkyunkwan University , Suwon, Gyeonggi-do 440-746, South Korea
- Department of Electrical Engineering, University of Engineering and Technology , Lahore, Pakistan
| | - Tian-Zi Shen
- School of Electronic and Electrical Engineering, Sungkyunkwan University , Suwon, Gyeonggi-do 440-746, South Korea
| | - Aurangzeb Rashid Masud
- School of Electronic and Electrical Engineering, Sungkyunkwan University , Suwon, Gyeonggi-do 440-746, South Korea
| | - Thilini K Ekanayaka
- School of Electronic and Electrical Engineering, Sungkyunkwan University , Suwon, Gyeonggi-do 440-746, South Korea
| | - Bomi Lee
- School of Electronic and Electrical Engineering, Sungkyunkwan University , Suwon, Gyeonggi-do 440-746, South Korea
| | - Jang-Kun Song
- School of Electronic and Electrical Engineering, Sungkyunkwan University , Suwon, Gyeonggi-do 440-746, South Korea
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23
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Narayan R, Kim JE, Kim JY, Lee KE, Kim SO. Graphene Oxide Liquid Crystals: Discovery, Evolution and Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:3045-68. [PMID: 26928388 DOI: 10.1002/adma.201505122] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 12/12/2015] [Indexed: 05/20/2023]
Abstract
The discovery and relevant research progress in graphene oxide liquid crystals (GOLCs), the latest class of 2D nanomaterials exhibiting colloidal liquid crystallinity arising from the intrinsic disc-like shape anisotropy, is highlighted. GOLC has conferred a versatile platform for the development of novel properties and applications based on the facile controllability of molecular scale alignment. The first part of this review offers a brief introduction to LCs, including the theoretical background. Particular attention has been paid to the different types of LC phases that have been reported thus far, such as nematic, lamellar and chiral phases. Several key parameters governing the ultimate stability of GOLC behavior, including pH and ionic strength of aqueous dispersions are highlighted. In a relatively short span of time since its discovery, GOLCs have proved their remarkable potential in a broad spectrum of applications, including highly oriented wet-spun fibers, self-assembled nanocomposites, and architectures for energy storage devices. The second part of this review is devoted to an exclusive overview of the relevant applications. Finally, an outlook is provided into this newly emerging research field, where two well established scientific communities for carbon nanomaterials and liquid crystals are ideally merged.
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Affiliation(s)
- Rekha Narayan
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science & Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Ji Eun Kim
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science & Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Ju Young Kim
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science & Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Kyung Eun Lee
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science & Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Sang Ouk Kim
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science & Engineering, KAIST, Daejeon, 34141, Republic of Korea
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24
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Shuai M, Klittnick A, Shen Y, Smith GP, Tuchband MR, Zhu C, Petschek RG, Mertelj A, Lisjak D, Čopič M, Maclennan JE, Glaser MA, Clark NA. Spontaneous liquid crystal and ferromagnetic ordering of colloidal magnetic nanoplates. Nat Commun 2016; 7:10394. [PMID: 26817823 PMCID: PMC4738347 DOI: 10.1038/ncomms10394] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 12/08/2015] [Indexed: 11/18/2022] Open
Abstract
Ferrofluids are familiar as colloidal suspensions of ferromagnetic nanoparticles in aqueous or organic solvents. The dispersed particles are randomly oriented but their moments become aligned if a magnetic field is applied, producing a variety of exotic and useful magnetomechanical effects. A longstanding interest and challenge has been to make such suspensions macroscopically ferromagnetic, that is having uniform magnetic alignment in the absence of a field. Here we report a fluid suspension of magnetic nanoplates that spontaneously aligns into an equilibrium nematic liquid crystal phase that is also macroscopically ferromagnetic. Its zero-field magnetization produces distinctive magnetic self-interaction effects, including liquid crystal textures of fluid block domains arranged in closed flux loops, and makes this phase highly sensitive, with it dramatically changing shape even in the Earth's magnetic field. Ferromagnetism has been known as a material property of solids since the time of the ancient Greeks. Here, Shuai et al. report that magnetic nanoplates suspended in a simple solvent can spontaneously align to form a ferromagnetic liquid, capable of both producing and sensing magnetic fields.
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Affiliation(s)
- M Shuai
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - A Klittnick
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - Y Shen
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - G P Smith
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - M R Tuchband
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - C Zhu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - R G Petschek
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - A Mertelj
- Jozef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - D Lisjak
- Jozef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - M Čopič
- Jozef Stefan Institute, SI-1000 Ljubljana, Slovenia.,Faculty of Mathematics and Physics, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - J E Maclennan
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - M A Glaser
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - N A Clark
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
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25
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MIYAMOTO N, YAMAMOTO S. Inorganic Nanosheet Liquid Crystals: Self-Assembled Structures in Dispersions of Two-Dimensional Inorganic Polymers. KOBUNSHI RONBUNSHU 2016. [DOI: 10.1295/koron.2015-0075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Nobuyoshi MIYAMOTO
- Department of Life, Environment, and Materials Science, Fukuoka Institute of Technology
- Faculty of Engineering, Graduate School of Fukuoka Institute of Technology
- Institute for Materials Chemistry and Engineering, Kyushu University
| | - Shinya YAMAMOTO
- Faculty of Engineering, Graduate School of Fukuoka Institute of Technology
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26
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Shu R, Yin Q, Xing H, Tan D, Gan Y, Xu G. Colloidal and rheological behavior of aqueous graphene oxide dispersions in the presence of poly(ethylene glycol). Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2015.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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27
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Lin F, Tong X, Wang Y, Bao J, Wang ZM. Graphene oxide liquid crystals: synthesis, phase transition, rheological property, and applications in optoelectronics and display. NANOSCALE RESEARCH LETTERS 2015; 10:435. [PMID: 26546325 PMCID: PMC4636539 DOI: 10.1186/s11671-015-1139-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/23/2015] [Indexed: 05/21/2023]
Abstract
Graphene oxide (GO) liquid crystals (LCs) are macroscopically ordered GO flakes dispersed in water or polar organic solvents. Since the first report in 2011, GO LCs have attracted considerable attention for their basic properties and potential device applications. In this review, we summarize recent developments and present a comprehensive understanding of GO LCs via many aspects ranging from the exfoliation of GO flakes from graphite, to phases and phase transitions under various conditions, the orientational responses of GO under external magnetic and electric fields, and finally Kerr effect and display applications. The emphasis is placed on the unique and basic properties of GO and their ordered assembly. We will also discuss challenges and issues that need to be overcome in order to gain a more fundamental understanding and exploit full device potentials of GO LCs.
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Affiliation(s)
- Feng Lin
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China.
| | - Xin Tong
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China.
| | - Yanan Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China.
- Department of Electrical and Computer Engineering, University of Houston, Houston, TX, 77204, USA.
| | - Jiming Bao
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China.
- Department of Electrical and Computer Engineering, University of Houston, Houston, TX, 77204, USA.
| | - Zhiming M Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China.
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China.
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28
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Ahmad RTM, Hong SH, Shen TZ, Song JK. Optimization of particle size for high birefringence and fast switching time in electro-optical switching of graphene oxide dispersions. OPTICS EXPRESS 2015; 23:4435-40. [PMID: 25836480 DOI: 10.1364/oe.23.004435] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
In order to use graphene oxide (GO) dispersions for electro-optical applications, both a high GO concentration and a high electrical sensitivity are essential; however, these have not been achieved to date. Here, we report that by optimizing the mean size of GO particles to approximately 0.5 μm, one can obtain a high GO concentration of up to 2 wt% and high electrical sensitivity simultaneously. By reducing the mean GO-particle size, the interparticle interaction and the rotational viscosity can be significantly reduced, and a high-concentration isotropic phase can be obtained. As a result, the maximum birefringence increases and the dynamic response becomes faster. However, further decrease of the mean size below 0.1 μm causes a decrease in the anisotropy of electrical polarizability, resulting in the reduction of the electrical sensitivity of GO dispersions.
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29
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Mederos L, Velasco E, Martínez-Ratón Y. Hard-body models of bulk liquid crystals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:463101. [PMID: 25335432 DOI: 10.1088/0953-8984/26/46/463101] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Hard models for particle interactions have played a crucial role in the understanding of the structure of condensed matter. In particular, they help to explain the formation of oriented phases in liquids made of anisotropic molecules or colloidal particles and continue to be of great interest in the formulation of theories for liquids in bulk, near interfaces and in biophysical environments. Hard models of anisotropic particles give rise to complex phase diagrams, including uniaxial and biaxial nematic phases, discotic phases and spatially ordered phases such as smectic, columnar or crystal. Also, their mixtures exhibit additional interesting behaviours where demixing competes with orientational order. Here we review the different models of hard particles used in the theory of bulk anisotropic liquids, leaving aside interfacial properties and discuss the associated theoretical approaches and computer simulations, focusing on applications in equilibrium situations. The latter include one-component bulk fluids, mixtures and polydisperse fluids, both in two and three dimensions, and emphasis is put on liquid-crystal phase transitions and complex phase behaviour in general.
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Affiliation(s)
- Luis Mederos
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz, 3, E-28049 Madrid, Spain
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30
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Pietra F, Rabouw FT, van Rhee PG, van Rijssel J, Petukhov AV, Erné BH, Christianen PCM, de Mello Donegá C, Vanmaekelbergh D. Self-assembled CdSe/CdS nanorod sheets studied in the bulk suspension by magnetic alignment. ACS NANO 2014; 8:10486-10495. [PMID: 25197767 DOI: 10.1021/nn503857t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We studied spontaneously self-assembled aggregates in a suspension of CdSe/CdS core/shell nanorods (NRs). The influence of the length and concentration of the NRs and the suspension temperature on the size of the aggregates was investigated using in situ small-angle X-ray scattering (SAXS) and linear dichroism (LD) measurements under high magnetic fields (up to 30 T). The SAXS patterns reveal the existence of crystalline 2-dimensional sheets of ordered NRs with an unusually large distance between the rods. The LD measurements show that the size of the sheets depends on the free-energy driving force for NR self-assembly. More precisely, the sheets are larger if the attraction between NRs is stronger, if the temperature is lower, or if the NR concentration is higher. We show that the formation of large NR sheets is a slow process that can take days. Our in situ results of the structures that spontaneously form in the bulk suspension could further our understanding of NR self-assembly into mono- or multilayer superlattices that occurs at the suspension/air interface upon evaporation of the solvent.
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Affiliation(s)
- Francesca Pietra
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science , Princetonplein 1, 3584 CC Utrecht, The Netherlands
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31
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Cinacchi G, Tani A. The isotropic–nematic phase transition in hard, slightly curved, lens-like particles. J Chem Phys 2014; 141:154901. [DOI: 10.1063/1.4897565] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Giorgio Cinacchi
- Departamento de Física Teórica de la Materia Condensada and Instituto de Física de la Materia Condensada, Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid, Spain
| | - Alessandro Tani
- Dipartimento di Chimica, Università di Pisa, Via Risorgimento 35, I-56100 Pisa, Italy
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32
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Wang X, Zhao D, Diaz A, Nava Medina IB, Wang H, Cheng Z. Thermo-sensitive discotic colloidal liquid crystals. SOFT MATTER 2014; 10:7692-7695. [PMID: 25175847 DOI: 10.1039/c4sm00797b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We fabricated for the first time thermo-sensitive discotic liquid crystals by grafting poly(N-isopropylacrylamide) (PNIPAM) onto zirconium phosphate (ZrP) platelets using pre-irradiated polymerization. The I-N transition was investigated by adjusting the temperature for a single set of samples. We found that soft disks self-assemble into nematic liquid crystals in a wider thickness-over-diameter ratio than do hard disks.
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Affiliation(s)
- Xuezhen Wang
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122, USA.
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Li H, Wang X, Chen Y, Cheng Z. Temperature-dependent isotropic-to-nematic transition of charged nanoplates. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:020504. [PMID: 25215677 DOI: 10.1103/physreve.90.020504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Indexed: 06/03/2023]
Abstract
Studies of temperature-dependent phase behaviors of discotic colloids are found infrequently in the literature. We establish here the isotropic-to-nematic (I-N) transition phase diagram of charged platelets in the temperature-versus-volume fraction plane. We discover that the N phase can be melted by increasing temperature, and that coexistent samples are more sensitive to polydispersity at higher temperature and higher concentration.
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Affiliation(s)
- Huawei Li
- Soft Matter Center, Guangdong Provincial Key Laboratory on Functional Soft Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China
| | - Xuezhen Wang
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA and Mary Kay O'Connor Process Safety Center, Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA
| | - Ying Chen
- Soft Matter Center, Guangdong Provincial Key Laboratory on Functional Soft Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China
| | - Zhengdong Cheng
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA and Mary Kay O'Connor Process Safety Center, Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA and Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843-3003, USA and Professional Program in Biotechnology, Texas A&M University, College Station, Texas 77843-3122, USA
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Schmiele M, Gehrer S, Westermann M, Steiniger F, Unruh T. Formation of liquid crystalline phases in aqueous suspensions of platelet-like tripalmitin nanoparticles. J Chem Phys 2014; 140:214905. [PMID: 24908039 DOI: 10.1063/1.4880723] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Suspensions of platelet-like shaped tripalmitin nanocrystals stabilized by the pure lecithin DLPC and the lecithin blend S100, respectively, have been studied by small-angle x-ray scattering (SAXS) and optical observation of their birefringence at different tripalmitin (PPP) concentrations φ(PPP). It could be demonstrated that the platelets of these potential drug delivery systems start to form a liquid crystalline phase already at pharmaceutically relevant concentrations φ(PPP) of less than 10 wt. %. The details of this liquid crystalline phase are described here for the first time. As in a previous study [A. Illing et al., Pharm. Res. 21, 592 (2004)] some platelets are found to self-assemble into lamellar stacks above a critical tripalmitin concentration φ(PPP)(st) of 4 wt. %. In this study another critical concentration φ(PPP)(lc) ≈ 7 wt. % for DLPC and φ(PPP)(lc) ≈ 9 wt. % for S100 stabilized dispersions, respectively, has been observed. φ(PPP)(lc) describes the transition from a phase of randomly oriented stacked lamellae and remaining non-assembled individual platelets to a phase in which the stacks and non-assembled platelets exhibit an overall preferred orientation. A careful analysis of the experimental data indicates that for concentrations above φ(PPP)(lc) the stacked lamellae start to coalesce to rather small liquid crystalline domains of nematically ordered stacks. These liquid crystalline domains can be individually very differently oriented but possess an overall preferred orientation over macroscopic length scales which becomes successively more expressed when further increasing φ(PPP). The lower critical concentration for the formation of liquid crystalline domains of the DLPC-stabilized suspension compared to φ(PPP)(lc) of the S100-stabilized suspension can be explained by a larger aspect ratio of the corresponding tripalmitin platelets. A geometrical model based on the excluded volumes of individual platelets and stacked lamellae has been developed and successfully applied to reproduce the critical volume fractions for both, the onset of stack formation and the appearance of the liquid crystalline phase.
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Affiliation(s)
- Martin Schmiele
- Professur für Nanomaterialcharakterisierung (Streumethoden), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - Simone Gehrer
- Professur für Nanomaterialcharakterisierung (Streumethoden), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - Martin Westermann
- Center for Electron Microscopy of the Jena University Hospital, Ziegelmühlenweg 1, 07743 Jena, Germany
| | - Frank Steiniger
- Center for Electron Microscopy of the Jena University Hospital, Ziegelmühlenweg 1, 07743 Jena, Germany
| | - Tobias Unruh
- Professur für Nanomaterialcharakterisierung (Streumethoden), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
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35
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Wang D, Hore MJA, Ye X, Zheng C, Murray CB, Composto RJ. Gold nanorod length controls dispersion, local ordering, and optical absorption in polymer nanocomposite films. SOFT MATTER 2014; 10:3404-3413. [PMID: 24643463 DOI: 10.1039/c3sm52514g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The dispersion, local orientation and optical absorption of polystyrene (PS, degree of polymerization P) nanocomposites containing PS-grafted gold nanorods (Au NRs, PS degree of polymerization N), with aspect ratios (ν = length/diameter) ranging from 2.5 to 6.3, are studied using quantitative scanning electron microscopy (SEM) and optical spectroscopy. The experimentally observed nanorod assemblies and optical absorptions are compared with predictions from self-consistent field theory (SCFT) and finite difference time domain (FDTD) calculations, respectively. A pair correlation function for Au NRs is calculated from SEM images, and contains no correlation peaks for P/N = 0.9, indicating nanorods are dispersed within the nanocomposite. Large correlation peaks are observed for P/N = 7.6, representative of interparticle separation distances within nanorod aggregates, which do not vary with ν. On the basis of SCFT calculations, aggregation is attributed to significant depletion-attraction forces in the composite for P/N > 1. When Au NRs disperse, the longitudinal surface plasmon resonance (LSPR) peak red shifts from the visible into the near-IR as ν increases. No shift in the dispersed LSPR position is observed for v = 2.5 and 3.3 upon aggregation because the ratio of the interparticle distance to the nanorod length is too large for surface plasmon coupling. However, for v = 6.3, significant coupling between surface plasmons leads to a blue shift of the LSPR by approximately 140 nm, in agreement with FDTD calculations.
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Affiliation(s)
- Dongliang Wang
- Department of Materials Science & Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104, USA.
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36
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Cienega-Cacerez O, Moreno-Razo JA, Díaz-Herrera E, Sambriski EJ. Phase equilibria, fluid structure, and diffusivity of a discotic liquid crystal. SOFT MATTER 2014; 10:3171-3182. [PMID: 24718439 DOI: 10.1039/c3sm52301b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Molecular Dynamics simulations were performed for the Gay-Berne discotic fluid parameterized by GB(0.345, 0.2, 1.0, 2.0). The volumetric phase diagram exhibits isotropic (IL), nematic (ND), and two columnar phases characterized by radial distribution functions: the transversal fluid structure varies between a hexagonal columnar (CD) phase (at higher temperatures and pressures) and a rectangular columnar (CO) phase (at lower temperatures and pressures). The slab-wise analysis of fluid dynamics suggests the formation of grain-boundary defects in the CO phase. Longitudinal fluid structure is highly periodic with narrow peaks for the CO phase, suggestive of a near-crystalline (yet diffusive) system, but is only short-ranged for the CD phase. The IL phase does not exhibit anisotropic diffusion. Transversal diffusion is more favorable in the ND phase at all times, but only favorable at short times for the columnar phases. In the columnar phases, a crossover occurs where longitudinal diffusion is favored over transversal diffusion at intermediate-to-long timescales. The anomalous diffusivity is pronounced in both columnar phases, with three identifiable contributions: (a) the rattling of discogens within a transient "interdigitation" cage, (b) the hopping of discogens across columns, and (c) the drifting motion of discogens along the orientation of the director.
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Affiliation(s)
- Octavio Cienega-Cacerez
- Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Delegación Iztapalapa México, D.F. 09340, México
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Shen TZ, Hong SH, Song JK. Electro-optical switching of graphene oxide liquid crystals with an extremely large Kerr coefficient. NATURE MATERIALS 2014; 13:394-9. [PMID: 24608144 DOI: 10.1038/nmat3888] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 01/20/2014] [Indexed: 05/02/2023]
Abstract
The sensitive response of the nematic graphene oxide (GO) phase to external stimuli makes this phase attractive for extending the applicability of GO and reduced GO to solution processes and electro-optic devices. However, contrary to expectations, the alignment of nematic GO has been difficult to control through the application of electric fields or surface treatments. Here, we show that when interflake interactions are sufficiently weak, both the degree of microscopic ordering and the direction of macroscopic alignment of GO liquid crystals (LCs) can be readily controlled by applying low electric fields. We also show that the large polarizability anisotropy of GO and Onsager excluded-volume effect cooperatively give rise to Kerr coefficients that are about three orders of magnitude larger than the maximum value obtained so far in molecular LCs. The extremely large Kerr coefficient allowed us to fabricate electro-optic devices with macroscopic electrodes, as well as well-aligned, defect-free GO over wide areas.
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Affiliation(s)
| | | | - Jang-Kun Song
- School of Information and Communication Engineering, Sungkyunkwan University, Jangan-Gu, Suwon, Gyeonggi-do 440-746, Korea
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38
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Delhorme M, Jönsson B, Labbez C. Gel, glass and nematic states of plate-like particle suspensions: charge anisotropy and size effects. RSC Adv 2014. [DOI: 10.1039/c4ra05555a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The influence of the charge anisotropy and platelet size on the formation of gel and glass states and nematic phases in suspensions of plate-like particles is investigated using Monte Carlo simulations in the canonical ensemble.
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Affiliation(s)
- Maxime Delhorme
- Laboratoire Interdisciplinaire Carnot de Bourgogne
- UMR 6303 CNRS
- Université de Bourgogne
- F-21078 Dijon, France
- Theoretical Chemistry
| | - Bo Jönsson
- Theoretical Chemistry
- Lund University
- Chemical Center
- S-221 00 Lund, Sweden
| | - Christophe Labbez
- Laboratoire Interdisciplinaire Carnot de Bourgogne
- UMR 6303 CNRS
- Université de Bourgogne
- F-21078 Dijon, France
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39
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Velasco E, Martínez-Ratón Y. Interplay between columnar and smectic stability in suspensions of polydisperse colloidal platelets. Phys Chem Chem Phys 2014; 16:765-75. [DOI: 10.1039/c3cp53065e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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Chen X, Gao H, Ploehn HJ. Montmorillonite–levan nanocomposites with improved thermal and mechanical properties. Carbohydr Polym 2014; 101:565-73. [DOI: 10.1016/j.carbpol.2013.09.073] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Revised: 09/18/2013] [Accepted: 09/21/2013] [Indexed: 11/28/2022]
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41
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Tkacz R, Oldenbourg R, Mehta SB, Miansari M, Verma A, Majumder M. pH dependent isotropic to nematic phase transitions in graphene oxide dispersions reveal droplet liquid crystalline phases. Chem Commun (Camb) 2014; 50:6668-71. [DOI: 10.1039/c4cc00970c] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The existence of a droplet liquid crystalline phase of graphene oxide (GO) is reported.
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Affiliation(s)
- Rachel Tkacz
- Nanoscale Science and Engineering Laboratory (NSEL)
- Mechanical and Aerospace Engineering Department
- Monash University
- Clayton, Australia
| | - Rudolf Oldenbourg
- Marine Biological Laboratory
- , USA
- Physics Department
- Brown University
- , USA
| | | | - Morteza Miansari
- Nanoscale Science and Engineering Laboratory (NSEL)
- Mechanical and Aerospace Engineering Department
- Monash University
- Clayton, Australia
| | | | - Mainak Majumder
- Nanoscale Science and Engineering Laboratory (NSEL)
- Mechanical and Aerospace Engineering Department
- Monash University
- Clayton, Australia
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42
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Jiang C, Huang H, Ma C, He T, Zhang F. Influence of particle size and tunable interactions on isotropic-nematic transition of block copolymer single crystal platelet suspensions. J Colloid Interface Sci 2013; 411:53-60. [PMID: 24112840 DOI: 10.1016/j.jcis.2013.08.054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/22/2013] [Accepted: 08/28/2013] [Indexed: 11/17/2022]
Abstract
We have studied the influence of the particle size and the tunable lateral interactions on the isotropic-nematic (I-N) phase transition of a plate-like colloidal system. The particles are single crystals of a block copolymer PS-b-PLLA (BCSC) prepared using a self-seeding procedure. These lozenge shape crystals have a uniform thickness and a narrowly distributed lateral size. The equilibrium phase behavior and I-N phase transition have been characterized using crossed polarizers at the room temperature. A nematic phase exists for all systems with size ranging from 700 to 4000 nm. For smaller crystals (<1200 nm), the I-N phase transition follows a process of slow sedimentation and subsequent macroscopic phase separation, resulting in a highly oriented nematic phase with a sharp I-N interface. For larger crystals (≥1200 nm), the I-N phase transition follows a process of nucleation and subsequent sedimentation, resulting in a random orientation of crystals in the nematic phase and a rough I-N interface. The I-N transition occurs at a very low volume fraction (<0.2%) for all systems, which is at least one order of magnitude lower than the theoretical prediction (2-7%). However, addition of a small amount of ethanol into the solution, the I-N transition can be significantly suppressed. These results demonstrate the existence of a lateral attraction between crystals, which is due to the polar attraction between the uncovered PLLA crystalline domains. Polar ethanol molecules can adsorb to the PLLA crystalline surface and screen the attraction. The attraction exhibits highly orientation-dependent. To further demonstrate this highly directional attraction, we have prepared two composite single crystal suspensions with PLLA homopolymer, which have a much wider open angle for the polar attraction. Indeed, the resulting liquid crystalline phases show much less horizontal ordering.
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Affiliation(s)
- Chunbo Jiang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China; University of Chinese Academy of Sciences, Beijing 10039, PR China.
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43
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Macroscopic assembled, ultrastrong and H(2)SO(4)-resistant fibres of polymer-grafted graphene oxide. Sci Rep 2013; 3:3164. [PMID: 24196491 PMCID: PMC3819614 DOI: 10.1038/srep03164] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 10/23/2013] [Indexed: 11/08/2022] Open
Abstract
Nacre realizes strength and toughness through hierarchical designs with primary "brick and mortar" structures of alternative arrangement of nanoplatelets and biomacromolecules, and these have inspired the fabrication of nanocomposites for decades. However, to simultaneously solve the three critical problems of phase separation, low interfacial strength and random orientation of nanofillers for nanocomposites is a great challenge yet. Here we demonstrate that polymer-grafted graphene oxide sheets are exceptional building blocks for nanocomposites. Their liquid crystalline dispersions can be wet-spun into continuous fibres. Because of well-ordering and efficient load transfer, the composites show remarkable tensile strength (500 MPa), three to four times higher than nacre. The uniform layered microstructures and strong interlayer interactions also endow the fibres good resistance to chemicals including 98% sulfuric acid. We studied the enhancing effect of nanofillers with fraction in a whole range (0-100%), and proposed an equation to depict the relationship.
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44
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Cui Y, Pizzey CL, van Duijneveldt JS. Modifying the structure and flow behaviour of aqueous montmorillonite suspensions with surfactant. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20120262. [PMID: 23459964 DOI: 10.1098/rsta.2012.0262] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Colloidal suspensions of plate-like particles undergo a variety of phase transitions. The predicted isotropic/nematic transition is often pre-empted by a sol/gel transition, especially in suspensions of the most commonly used natural swelling clay montmorillonite (MMT). A number of factors, including charge interactions, flexibility and salt concentration, may contribute to this competition. In this study, the effect of surfactant adsorption on suspensions of MMT was studied using rheology, small-angle X-ray scattering, static light scattering and optical microscopy. The addition of a polyetheramine surfactant reduced the moduli of the system and shifted the sol/gel transition to a much higher clay concentration, compared with suspensions of bare clay particles. Yet, scattering data revealed no change in suspension structure on length scales up to around a micrometre. Primary aggregates remain at this length scale and no nematic phase is formed. There is, however, a change in structure at large length scales (of order 20 μm) where light scattering indicates the presence of string-like aggregates that disappear on addition of surfactant. Microscope images of dried suspensions also revealed a string-like structure. The dried strings show strong birefringence and may consist of concentric cylinders, self-assembled from clay sheets.
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Affiliation(s)
- Yannan Cui
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
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45
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Miyamoto N, Nakato T. Liquid Crystalline Inorganic Nanosheet Colloids Derived From Layered Materials. Isr J Chem 2012. [DOI: 10.1002/ijch.201200033] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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46
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Martínez-Ratón Y, Velasco E. Effect of polydispersity, bimodality, and aspect ratio on the phase behavior of colloidal platelet suspensions. J Chem Phys 2012; 137:134906. [DOI: 10.1063/1.4755958] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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47
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Fartaria RP, Javid N, Sefcik J, Sweatman MB. Simulation of scattering and phase behavior around the isotropic–nematic transition of discotic particles. J Colloid Interface Sci 2012; 377:94-104. [DOI: 10.1016/j.jcis.2012.03.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 03/13/2012] [Accepted: 03/14/2012] [Indexed: 10/28/2022]
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48
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Chang YW, Mejia AF, Cheng Z, Di X, McKenna GB. Gelation via ion exchange in discotic suspensions. PHYSICAL REVIEW LETTERS 2012; 108:247802. [PMID: 23004332 DOI: 10.1103/physrevlett.108.247802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 04/30/2012] [Indexed: 06/01/2023]
Abstract
The phase behavior of charged disk suspensions displays a strong dependence on ionic strengths, as the interplay between excluded volume and electrostatic interactions determines the formation of glasses, gels, and liquid crystal states. The various ions in natural soil or brine, however, could present additional effects, especially considering that most platelet structures bear a momentous ion-exchange capacity. Here we observed how ion exchange modulates and controls the interaction between individual disks and leads to unconventional phase transitions from isotropic gel to nematic gel and finally to nematic liquid crystals.
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Affiliation(s)
- Ya-Wen Chang
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, USA
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49
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Mejia AF, Chang YW, Ng R, Shuai M, Mannan MS, Cheng Z. Aspect ratio and polydispersity dependence of isotropic-nematic transition in discotic suspensions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061708. [PMID: 23005115 DOI: 10.1103/physreve.85.061708] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 04/30/2012] [Indexed: 06/01/2023]
Abstract
We demonstrate the strong dependency of the isotropic-nematic (I-N) transition of discotic suspensions on the aspect ratio (ξ = thickness/diameter) via control of the sizes of pristine ZrP crystals and subsequent exfoliation to monolayers. The size fractionation of the I-N transition facilitates the analysis of the effect of polydispersity. A systematic variation in the aspect ratio in the low aspect ratio region (0.001 < ξ < 0.01) showed that the I-N transition volume fraction increases with the aspect ratio in agreement with computer simulations. It was found that the transition volume fractions scale with aspect ratio φ_{I,N} = mξ^{1.36±0.07}, where the prefactor m strongly depends on size polydispersity for φ_{N} but does not depend on size polydispersity for φ_{I} with φ_{I} and φ_{N} being the volume fractions of the isotropic and the nematic phases on the cloud curves, respectively.
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Affiliation(s)
- Andres F Mejia
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA
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50
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Delhorme M, Labbez C, Jönsson B. Liquid Crystal Phases in Suspensions of Charged Plate-Like Particles. J Phys Chem Lett 2012; 3:1315-20. [PMID: 26286776 DOI: 10.1021/jz300380n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Anisotropic interactions in colloidal suspensions have recently emerged as a route for the design of new soft materials. Nonisotropic particles can form nematic, smectic, hexatic, and columnar liquid crystals. Although the formation of these phases is well rationalized when excluded volume is solely at play, the role of electrostatic interactions still remains unclear and even less so when particles present a charge heterogeneity, for example, clays. Here, we use Monte Carlo simulations of concentrated suspensions of charged disk-like particles to reveal the role of Coulomb interactions and charge anisotropy underlying liquid crystal formation and structures. We observe a vast zoo of exotic structures, going from hexatic to columnar phases, which are shown to be controlled by the charge anisotropy. The particle volume fraction at which these phases start to form is found to decrease with increasing Coulomb interactions and charge anisotropy, which suggests a route to tune the structure of aqueous liquid crystals.
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Affiliation(s)
- Maxime Delhorme
- †Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Université de Bourgogne, 21078 Dijon Cedex, France
| | - Christophe Labbez
- †Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Université de Bourgogne, 21078 Dijon Cedex, France
| | - Bo Jönsson
- ‡Department of Theoretical Chemistry, Chemical Center, POB 124, S-221 00 Lund, Sweden
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