1
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Atata SB, Lelidis I. Exploring Quantum Dots Size Impact at Phase Diagram and Electrooptical Properties in 8CB Liquid Crystal Soft-Nanocomposites. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2980. [PMID: 37999334 PMCID: PMC10674785 DOI: 10.3390/nano13222980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/08/2023] [Accepted: 11/17/2023] [Indexed: 11/25/2023]
Abstract
We explore the influence of functionalized core-shell CdSe/ZnS quantum dots on the properties of the host liquid crystal compound 4-cyano-4'-octylbiphenyl (8CB) through electrooptical measurements. Two different diameters of quantum dots are used to investigate the size effects. We assess both the dispersion quality of the nanoparticles within the mixtures and the phase stability of the resulting anisotropic soft nanocomposites using polarizing optical microscopy. The temperature-mass fraction phase diagrams of the nanocomposites reveal deviations from the linear behavior in the phase stability lines. We measure the birefringence, the threshold voltage of the Fréedericksz transition, and the electrooptic switching times of the nanocomposite systems in planar cell geometry as functions of temperature, mass fraction, and diameter of the quantum dots. Beyond a critical mass fraction of the dopant nanoparticles, the nematic order is strongly reduced. Furthermore, we investigate the impact of the nanoparticle size and mass fraction on the viscoelastic coefficient. The anchoring energy at the interfaces of the liquid crystal with the cell and the quantum dots is estimated.
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Affiliation(s)
| | - Ioannis Lelidis
- Faculty of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, 15784 Athens, Greece
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2
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Jańczuk ZZ, Jedrych A, Parzyszek S, Gardias A, Szczytko J, Wojcik M. Dynamically Tunable Assemblies of Superparamagnetic Nanoparticles Stabilized with Liquid Crystal-like Ligands in Organic Thin Films. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2908. [PMID: 37947752 PMCID: PMC10648093 DOI: 10.3390/nano13212908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/29/2023] [Accepted: 10/30/2023] [Indexed: 11/12/2023]
Abstract
The process of arranging magnetic nanoparticles (MNPs) into long-range structures that can be dynamically and reversibly controlled is challenging, although interesting for emerging spintronic applications. Here, we report composites of MNPs in excess of LC-like ligands as promising materials for MNP-based technologies. The organic part ensures the assembly of MNP into long-range ordered phases as well as precise and temperature-reversible control over the arrangement. The dynamic changes are fully reversible, which we confirm using X-ray diffraction (XRD). This methodology allows for the precise control of the nanomaterial's structure in a thin film at different temperatures, translating to variable unit cell parameters. The composition of the materials (XPS, TGA), their structure (XRD), and magnetic properties (SQUID) were performed. Overall, this study confirms that LC-like materials provide the ability to dynamically control the magnetic nanoparticles in thin films, particularly the reversible control of their self-organization.
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Affiliation(s)
- Zuzanna Z. Jańczuk
- Faculty of Chemistry, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland; (Z.Z.J.); (A.J.); (S.P.)
| | - Agnieszka Jedrych
- Faculty of Chemistry, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland; (Z.Z.J.); (A.J.); (S.P.)
| | - Sylwia Parzyszek
- Faculty of Chemistry, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland; (Z.Z.J.); (A.J.); (S.P.)
| | - Anita Gardias
- Faculty of Physics, University of Warsaw, 5 Pasteur Street, 02-093 Warsaw, Poland; (A.G.); (J.S.)
| | - Jacek Szczytko
- Faculty of Physics, University of Warsaw, 5 Pasteur Street, 02-093 Warsaw, Poland; (A.G.); (J.S.)
| | - Michal Wojcik
- Faculty of Chemistry, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland; (Z.Z.J.); (A.J.); (S.P.)
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3
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Lal A, Verma H, Chirra S, Dhar R, Dabrowski R, Pandey KL. Gold Nanorod-Induced Effects in a Mesogenic Compound 4-( trans-4- n-Hexylcyclohexyl) isothiocyanatobenzene. ACS OMEGA 2023; 8:29012-29024. [PMID: 37599970 PMCID: PMC10433484 DOI: 10.1021/acsomega.3c01863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 07/21/2023] [Indexed: 08/22/2023]
Abstract
Gold nanorods (GNRs) have a capsule-like structure with different optical properties than spherical gold nanoparticles due to surface plasmon resonance. Liquid crystals (LCs) are mesogenic compounds having crystal-like orientation and liquid-like fluidity. They are important materials from a technological point of view. Both GNRs and LC compounds are anisotropic in shape and properties. Different nano entities show interesting results when dispersed in different liquid crystalline materials which are instrumental from the application point of view. In the present work, GNRs have been dispersed in nematic liquid crystalline materials, namely 4-(trans-4-n-hexylcyclohexyl) isothiocyanatobenzene (6CHBT). Calorimetric, texture, spectroscopic, and dielectric studies were carried out for a pure 6CHBT and its composites with GNRs. Different calorimetric and dielectric parameters such as transition temperature, enthalpy, heat flow, permittivity, dielectric strength, dielectric anisotropy, and relaxation frequency have been determined, and the effect of GNRs has been explored. This article gives an insight into the influence of GNRs on the morphology and anisotropic physical properties of the nematic liquid crystalline material.
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Affiliation(s)
- Abhinav Lal
- Department
of Chemistry, Ewing Christian College, University
of Allahabad, Prayagraj 211003, India
- Centre
of Material Sciences, University of Allahabad, Prayagraj 211002, India
| | - Himanshu Verma
- Centre
of Material Sciences, University of Allahabad, Prayagraj 211002, India
| | - Saikumar Chirra
- Centre
of Material Sciences, University of Allahabad, Prayagraj 211002, India
- Department
of Physics, Ewing Christian College, University
of Allahabad, Prayagraj 211003, India
| | - Ravindra Dhar
- Centre
of Material Sciences, University of Allahabad, Prayagraj 211002, India
| | - Roman Dabrowski
- Department
of Applied Sciences and Chemistry, Military
University of Technology, Warsaw 00-908, Poland
| | - Kusum Lata Pandey
- Department
of Physics, Ewing Christian College, University
of Allahabad, Prayagraj 211003, India
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4
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Singh B, Sikarwar S, Agarwal S, Singh DP, Pandey KK, Manohar R. Chemically Functionalized Gold Nanosphere-Blended Nematic Liquid Crystals for Photonic Applications. ACS OMEGA 2023; 8:2315-2327. [PMID: 36687113 PMCID: PMC9850737 DOI: 10.1021/acsomega.2c06718] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023]
Abstract
A demand for functional materials that are capable of tailoring light-emissive properties has apparently been rising nowadays substantially for their utilization in organic optoelectronic devices. Motivated by such promising characteristics, we present highly emissive as well as aggregation-induced emission (AIE) electroluminescent composite systems composed of a nematic liquid crystals (NLC) blended with polyethylene-functionalized gold nanospheres (GNSs). The major findings of this study include superior electro-optical properties such as threshold voltage reduction by around 24%. The fall time is reduced by 11.50, 30.33, 49.33, and 63.17% respectively, and rotational viscosity is reduced by 13.86, 32.77, 36.97, and 49.58% for 5.0 × 1011, 5.0 × 1012, 2.5 × 1013, and 5.0 × 1013 number of GNS-blended liquid crystal (LC) cells. The increased UV absorbance and greatly enhanced luminescence properties have been attributed to surface plasmon resonance near the surface of GNSs and AIE effect risen due to agglomeration of the capping agent with the NLC molecules respectively, and these characteristics make them suitable for new-age display applications.
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Affiliation(s)
- Bhupendra
Pratap Singh
- Liquid
Crystal Research Laboratory, Department of Physics, University of Lucknow, Lucknow226007, India
| | - Samiksha Sikarwar
- Integrated
Basic Science, School of Physical and Decision Science, Babasaheb Bhimrao Ambedkar University, Lucknow226025, India
| | - Shikha Agarwal
- Liquid
Crystal Research Laboratory, Department of Physics, University of Lucknow, Lucknow226007, India
| | - Dharmendra Pratap Singh
- Université
du Littoral Côte d’Opale, UR 4476, UDSMM, Unité de Dynamique et Structure des Matériaux
Moléculaires, Calais62228, France
| | - Kamal Kumar Pandey
- Department
of Physics, Shri Jai Narain Misra Post Graduate
College, Lucknow226001, India
| | - Rajiv Manohar
- Liquid
Crystal Research Laboratory, Department of Physics, University of Lucknow, Lucknow226007, India
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5
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Kovalchuk O, Kovalchuk T, Tomašovičová N, Timko M, Zakutanska K, Miakota D, Kopčanský P, Shevchuk O, Garbovskiy Y. Dielectric and electrical properties of nematic liquid crystals 6CB doped with iron oxide nanoparticles. The combined effect of nanodopant concentration and cell thickness. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Anu, Varshney D, Yadav K, Prakash J, Meena H, Singh G. Tunable dielectric and memory features of ferroelectric layered perovskite Bi4Ti3O12 nanoparticles doped nematic liquid crystal composite. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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7
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Functionalized and non-functionalized Multi Walled Carbon Nanotubes in the anisotropic media of liquid crystalline material. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Kaur G, Khushboo, Malik P. Mesomorphic, electro-optic and dielectric behavior of self-assembled nanocomposite materials: Nematic mixture doped with carbon coated cobalt nanoparticles. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Nanoparticle-Induced Property Changes in Nematic Liquid Crystals. NANOMATERIALS 2022; 12:nano12030341. [PMID: 35159688 PMCID: PMC8839905 DOI: 10.3390/nano12030341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/18/2022] [Accepted: 01/18/2022] [Indexed: 11/30/2022]
Abstract
Doping liquid crystals with nanoparticles is a widely accepted method to enhance liquid crystal’s intrinsic properties. In this study, a quick and reliable method to characterise such colloidal suspensions using an optical multi-parameter analyser, a cross-polarised intensity measurement-based device, is presented. Suspensions characterised in this work are either plasmonic (azo-thiol gold AzoGNPs) or ferroelectric Sn2P2S6 (SPS) nanoparticles in nematic liquid crystals. The elastic constants and rotational viscosity showed nonlinear dependence on the concentration of AzoGNPs, initially increasing at lower concentrations and then decreasing at higher concentrations, indicating some degree of particle aggregation. For the SPS suspension, the elastic constant decreased with doping, while the rotational viscosity increased, in agreement with previous findings. Through viscosity measurements, the stability of SPS suspension over ten years is also highlighted.
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10
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Recent Progresses on Experimental Investigations of Topological and Dissipative Solitons in Liquid Crystals. CRYSTALS 2022. [DOI: 10.3390/cryst12010094] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Solitons in liquid crystals have received increasing attention due to their importance in fundamental physical science and potential applications in various fields. The study of solitons in liquid crystals has been carried out for over five decades with various kinds of solitons being reported. Recently, a number of new types of solitons have been observed, among which, many of them exhibit intriguing dynamic behaviors. In this paper, we briefly review the recent progresses on experimental investigations of solitons in liquid crystals.
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11
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Abstract
Smart soft materials are envisioned to be the building blocks of the next generation of advanced devices and digitally augmented technologies. In this context, liquid crystals (LCs) owing to their responsive and adaptive attributes could serve as promising smart soft materials. LCs played a critical role in revolutionizing the information display industry in the 20th century. However, in the turn of the 21st century, numerous beyond-display applications of LCs have been demonstrated, which elegantly exploit their controllable stimuli-responsive and adaptive characteristics. For these applications, new LC materials have been rationally designed and developed. In this Review, we present the recent developments in light driven chiral LCs, i.e., cholesteric and blue phases, LC based smart windows that control the entrance of heat and light from outdoor to the interior of buildings and built environments depending on the weather conditions, LC elastomers for bioinspired, biological, and actuator applications, LC based biosensors for detection of proteins, nucleic acids, and viruses, LC based porous membranes for the separation of ions, molecules, and microbes, living LCs, and LCs under macro- and nanoscopic confinement. The Review concludes with a summary and perspectives on the challenges and opportunities for LCs as smart soft materials. This Review is anticipated to stimulate eclectic ideas toward the implementation of the nature's delicate phase of matter in future generations of smart and augmented devices and beyond.
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Affiliation(s)
- Hari Krishna Bisoyi
- Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, United States
| | - Quan Li
- Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, United States.,Institute of Advanced Materials, School of Chemistry and Chemical Engineering, and Jiangsu Hi-Tech Key Laboratory for Biomedical Research, Southeast University, Nanjing 211189, China
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12
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Sagnelli D, Calabrese M, Kaczmarczyk O, Rippa M, Vestri A, Marchesano V, Kortsen K, Cuzzucoli Crucitti V, Villani F, Loffredo F, Borriello C, Nenna G, Cocca M, Ambrogi V, Matczyszyn K, Simoni F, Petti L. Photo-Responsivity Improvement of Photo-Mobile Polymers Actuators Based on a Novel LCs/Azobenzene Copolymer and ZnO Nanoparticles Network. NANOMATERIALS 2021; 11:nano11123320. [PMID: 34947671 PMCID: PMC8705796 DOI: 10.3390/nano11123320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/28/2021] [Accepted: 12/01/2021] [Indexed: 11/25/2022]
Abstract
The efficiency of photomobile polymers (PMP) in the conversion of light into mechanical work plays a fundamental role in achieving cutting-edge innovation in the development of novel applications ranging from energy harvesting to sensor approaches. Because of their photochromic properties, azobenzene monomers have been shown to be an efficient material for the preparation of PMPs with appropriate photoresponsivity. Upon integration of the azobenzene molecules as moieties into a polymer, they act as an engine, allowing fast movements of up to 50 Hz. In this work we show a promising approach for integrating ZnO nanoparticles into a liquid crystalline polymer network. The addition of such nanoparticles allows the trapping of incoming light, which acts as diffusive points in the polymer matrix. We characterized the achieved nanocomposite material in terms of thermomechanical and optical properties and finally demonstrated that the doped PMP was better performing that the undoped PMP film.
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Affiliation(s)
- Domenico Sagnelli
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (M.C.); (O.K.); (M.R.); (A.V.); (V.M.); (F.S.)
- Correspondence: (D.S.); (G.N.); (L.P.)
| | - Marcella Calabrese
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (M.C.); (O.K.); (M.R.); (A.V.); (V.M.); (F.S.)
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, 80125 Naples, Italy;
| | - Olga Kaczmarczyk
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (M.C.); (O.K.); (M.R.); (A.V.); (V.M.); (F.S.)
- Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland;
| | - Massimo Rippa
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (M.C.); (O.K.); (M.R.); (A.V.); (V.M.); (F.S.)
| | - Ambra Vestri
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (M.C.); (O.K.); (M.R.); (A.V.); (V.M.); (F.S.)
| | - Valentina Marchesano
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (M.C.); (O.K.); (M.R.); (A.V.); (V.M.); (F.S.)
| | - Kristoffer Kortsen
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK;
| | - Valentina Cuzzucoli Crucitti
- Department of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK;
| | - Fulvia Villani
- ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Portici Research Centre, Portici, 80055 Naples, Italy; (F.V.); (F.L.); (C.B.)
| | - Fausta Loffredo
- ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Portici Research Centre, Portici, 80055 Naples, Italy; (F.V.); (F.L.); (C.B.)
| | - Carmela Borriello
- ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Portici Research Centre, Portici, 80055 Naples, Italy; (F.V.); (F.L.); (C.B.)
| | - Giuseppe Nenna
- ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Portici Research Centre, Portici, 80055 Naples, Italy; (F.V.); (F.L.); (C.B.)
- Correspondence: (D.S.); (G.N.); (L.P.)
| | - Mariacristina Cocca
- Institute for Polymers, Composites and Biomaterials of CNR, 80072 Pozzuoli, Italy;
| | - Veronica Ambrogi
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, 80125 Naples, Italy;
| | - Katarzyna Matczyszyn
- Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland;
| | - Francesco Simoni
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (M.C.); (O.K.); (M.R.); (A.V.); (V.M.); (F.S.)
| | - Lucia Petti
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (M.C.); (O.K.); (M.R.); (A.V.); (V.M.); (F.S.)
- Correspondence: (D.S.); (G.N.); (L.P.)
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13
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Latha BK, Dhara S, Sastry VSS. Topological phase transitions in two-dimensional bent-core liquid crystal models. Phys Rev E 2021; 104:064701. [PMID: 35030859 DOI: 10.1103/physreve.104.064701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
Two-dimensional liquid crystal (LC) models of interacting V-shaped bent-core molecules with two rigid rodlike identical segments connected at a fixed angle (θ=112^{∘}) are investigated. The model assigns equal biquadratic tensor coupling among constituents of the interacting neighboring molecules on a square lattice, allowing for reorientations in three dimensions (d=2, n=3). We find evidence of two temperature-driven topological transitions mediated by point disclinations associated with the three ordering directors, condensing the LC medium successively into uniaxial and biaxial phases. With Monte Carlo simulations, temperature dependencies of the system energy, specific heat, orientational order parameters, topological order parameters, and densities of unbound topological defects of the different ordering directors are computed. The high-temperature transition results in topological ordering of disclinations of the primary director, imparting uniaxial symmetry to the phase. The low-temperature transition precipitates simultaneous topological ordering of defects of the remaining directors, resulting in biaxial symmetry. The correlation functions, quantifying spatial variations of the orientational correlations of the molecular axes show exponential decays in the high-temperature (disordered) phase, and power-law decays in the low-temperature (biaxial) phase. Differing temperature dependencies of the topological parameters point to a significant degree of cross coupling among the uniaxial and biaxial tensors of interacting molecules. This simplified Hamiltonian leaves θ as the only free model parameter, and the system traces a θ-dependent trajectory in a plane of the phenomenological parameter space.
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Affiliation(s)
- B Kamala Latha
- School of Physics, University of Hyderabad, Hyderabad 500046, India
| | - Surajit Dhara
- School of Physics, University of Hyderabad, Hyderabad 500046, India
| | - V S S Sastry
- Centre for Modelling, Simulation and Design, University of Hyderabad, Hyderabad 500046, India
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14
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Parzyszek S, Pociecha D, Wolska JM, Lewandowski W. Thermomechanically controlled fluorescence anisotropy in thin films of InP/ZnS quantum dots. NANOSCALE ADVANCES 2021; 3:5387-5392. [PMID: 36132630 PMCID: PMC9418115 DOI: 10.1039/d1na00290b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 08/05/2021] [Indexed: 06/03/2023]
Abstract
Macroscopic scale sources of polarized light play a fundamental role in designing light-emitting devices. In this communication we report the formation of nano- and macro-scale ordered, layered assemblies of InP/ZnS quantum dots (QDs) exhibiting fluorescence anisotropy (FA), as well as thermo- and mechano-responsive properties. The long-range organization of small, quasi-isotropic nanoparticles was achieved by introducing liquid crystal molecules to the surface of QDs, without the need to use an organic matrix. Melting/crystallization of the ligand at 95 deg. C translated to a reversible reconfiguration of QDs thin film between 2D layered and body-centered cubic structures, characteristic for a temperature range below and above the melting point, respectively. The low-temperature, layered structure exhibited mechano-responsiveness which was key to introduce and control the sample alignment. Interestingly, transverse and parallel alignment modes of QDs layers were achieved, depending on the temperature of mechanical shearing. As prepared QD samples exhibited fluorescence anisotropy strongly correlated to the macroscopic orientation of the layers. Correlated small-angle X-ray diffraction (SAXRD) and fluorescence spectroscopy studies confirmed the mm-scale alignment of the thin films of QDs. Such films may be advantageous for developing efficient, densely packed, and uniform macro-scale FA sources.
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Affiliation(s)
- Sylwia Parzyszek
- Faculty of Chemistry, University of Warsaw Pasteura 1 st. 02-093 Warsaw Poland
| | - Damian Pociecha
- Faculty of Chemistry, University of Warsaw Pasteura 1 st. 02-093 Warsaw Poland
| | - Joanna Maria Wolska
- Faculty of Chemistry, University of Warsaw Pasteura 1 st. 02-093 Warsaw Poland
| | - Wiktor Lewandowski
- Faculty of Chemistry, University of Warsaw Pasteura 1 st. 02-093 Warsaw Poland
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15
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Karpov ON, Bondarenko GN, Merekalov AS, Shandryuk GA, Zhigalina OM, Khmelenin DN, Skryleva EA, Golovan LA, Talroze RV. Formation of the Inorganic and Organic Shells on the Surface of CdSe Quantum Dots. ACS APPLIED MATERIALS & INTERFACES 2021; 13:36190-36200. [PMID: 34286582 DOI: 10.1021/acsami.1c10315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Embedding quantum dots (QDs) into an organic matrix of controllable order requires the identification of their structural characteristics. This analysis is necessary for the creation of anisotropic composites that are sensitive to external stimuli. We have studied the QD structures formed during the single-step synthesis of CdSe/ZnS QDs and their transformations after the initial ligand's substitution for another ligand. This single-step process leads to the formation of the core/shell structure. We detect the presence of two oleic acid residues ionically connected to Zn and Cd. At the same time, the amount of Cd oleate at the surface is very small. We observe the ligand exchange process at the surface of the core/shell QDs. The oleic acid residues are substituted by terphenyl-containing (TERPh-COOH) aromatic acid residues. The reaction between CdSe/ZnS carrying TOP and oleic acid residues ionically bound with QDs and terphenyl-containing acid leads to the coexistence of multiple ligands on the QD surface at a ratio of 11:6:33 for TOP/OA/TERPh-COOH.
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Affiliation(s)
- Oleg N Karpov
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
| | - Galina N Bondarenko
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
| | - Alexey S Merekalov
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
| | - Georgiy A Shandryuk
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
| | - Olga M Zhigalina
- Shubnikov Institute of Crystallography, Federal Research Center "Crystallography and Photonics", Russian Academy of Sciences, Moscow 119333, Russia
- Bauman Moscow State Technical University, Moscow 105005, Russia
| | - Dmitriy N Khmelenin
- Shubnikov Institute of Crystallography, Federal Research Center "Crystallography and Photonics", Russian Academy of Sciences, Moscow 119333, Russia
| | - Elena A Skryleva
- National University of Science and Technology MISIS, Leninsky pr. 4, Moscow 119049, Russia
| | - Leonid A Golovan
- Faculty of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russia
| | - Raisa V Talroze
- A.V. Topchiev Institute of Petrochemical Synthesis Russian Academy of Sciences, Moscow 119991, Russia
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16
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Association of Graphene Silver Polymethyl Methacrylate (PMMA) with Photodynamic Therapy for Inactivation of Halitosis Responsible Bacteria in Denture Wearers. NANOMATERIALS 2021; 11:nano11071643. [PMID: 34201467 PMCID: PMC8305032 DOI: 10.3390/nano11071643] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/13/2022]
Abstract
(1) Background: Poor hygiene and denture presence in the oral cavity are factors that favor bacterial accumulation, the cause of halitosis and of various oral and general diseases. Aim: This study aimed to evaluate the possibility of inactivating bacteria associated with halitosis in acrylic denture wearers using polymethyl methacrylate resin enhanced with graphene silver nanoparticles and the effect of the resin association with extra oral photodynamic therapy. (2) Methods: Graphene silver nanoparticles in 1 and 2 wt% were added to a commercial acrylic resin powder. Three study groups containing samples from the three different materials were established. The first group was not exposed to the light treatment, and the other two were exposed to red light (laser and light emitting diode) after photosensitizer placement on the disk’s surface. Samples were incubated with Porphyromonas gingivalis and Enterococcus faecalis. (3) Results: For both bacterial strains, inhibition zones were obtained, showing significant differences for the light-treated samples. (4) Conclusions: Denture resins with antibacterial properties associated with extra oral photodynamic therapy exhibited enhanced antibacterial effects. The procedure could be used as a safer and more efficient alternative technique against halitosis and oral infections in denture wearers.
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Das P, Praveen PL. Structure and phase behavior of alkoxy benzoic acids in DMSO for thermodynamic applications: Theoretical investigation. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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18
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Elamathi M, John Peter A. Exciton radiative recombination time in a group III-V/II-VI core/shell quantum dot: Simultaneous effects of pressure and temperature. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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19
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Garbovskiy Y. Conventional and unconventional ionic phenomena in tunable soft materials made of liquid crystals and nanoparticles. NANO EXPRESS 2021. [DOI: 10.1088/2632-959x/abe652] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
A great variety of tunable multifunctional materials can be produced by combining nanoparticles and liquid crystals. Typically, the tunability of such soft nanocomposites is achieved via external electric fields resulting in the field-induced reorientation of liquid crystals. This reorientation can be altered by ions normally present in liquid crystals in small quantities. In addition, nanomaterials dispersed in liquid crystals can also affect the behavior of ions. Therefore, an understanding of ionic phenomena in liquid crystals doped with nanoparticles is essential for future advances in liquid crystal-aided nanoscience and nanotechnology. This paper provides an overview of the ionic effects observed in liquid crystals doped with nanomaterials. An introduction to liquid crystals is followed by a brief overview of nanomaterials in liquid crystals. After giving a basic description of ions in liquid crystals and experimental methods to measure them, a wide range of ionic phenomena in liquid crystals doped with different types of nanomaterials is discussed. After that, both existing and emerging applications of tunable soft materials made of liquid crystals and nanodopants are presented with an emphasis on the role of ionic effects in such systems. Finally, the discussion of unsolved problems and future research directions completes the review.
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Yang D, Seo K, Kang H. Alignment Layer of Liquid Crystal Using Plant-Based Isoeugenol-Substituted Polystyrene. Polymers (Basel) 2021; 13:547. [PMID: 33673311 PMCID: PMC7918683 DOI: 10.3390/polym13040547] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/04/2021] [Accepted: 02/09/2021] [Indexed: 01/12/2023] Open
Abstract
We synthesized a series of renewable and plant-based isoeugenol-substituted polystyrenes (PIEU#, # = 100, 80, 60, 40, and 20, where # is the molar percent content of isoeugenol moiety), using polymer modification reactions to study their liquid crystal (LC) alignment behavior. In general, the LC cells fabricated using polymer film with a higher molar content of isoeugenol side groups showed vertical LC alignment behavior. This alignment behavior was well related to the surface energy value of the polymer layer. For example, vertical alignments were observed when the polar surface energy value of the polymer was smaller than approximately 3.59 mJ/m2, generated by the nonpolar isoeugenol moiety with long and bulky carbon groups. Good alignment stability at 100 °C and under ultraviolet (UV) irradiation of 15 J/cm2 was observed for the LC cells fabricated using PIEU100 as a LC alignment layer. Therefore, renewable isoeugenol-based materials can be used to produce an eco-friendly vertical LC alignment system.
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Affiliation(s)
| | | | - Hyo Kang
- BK-21 Four Graduate Program, Department of Chemical Engineering, Dong-A University, 37 Nakdong Daero 550beon-gil, Saha-gu, Busan 604-714, Korea; (D.Y.); (K.S.)
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21
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Morozov VN, Kolyvanova MA, Dement'eva OV, Rudoy VM, Kuzmin VA. Comparison of quenching efficacy of SYBR Green I and PicoGreen fluorescence by ultrasmall gold nanoparticles in isotropic and liquid-crystalline DNA systems. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114751] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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22
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Uttam R, Kumar S, Dhar R. Magnified charge carrier conduction, permittivity, and mesomorphic properties of columnar structure of a room temperature discotic liquid crystalline material due to the dispersion of low concentration ferroelectric nanoparticles. Phys Rev E 2020; 102:052702. [PMID: 33327178 DOI: 10.1103/physreve.102.052702] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/06/2020] [Indexed: 11/07/2022]
Abstract
Liquid crystal nanocomposites have been a hot topic of research due to optimization of physical properties with such blending. There are several reports on enhancement of physical properties of nematic liquid crystals due to the blending of the nanomaterials. L. M. Lopatina and J. V. Selinger [Phys. Rev. Lett. 102, 197802 (2009)]10.1103/PhysRevLett.102.197802 have even proposed a theory based on experimental results for the enhancement of the properties of the nematic mesophase in the presence of ferroelectric nanoparticles. However, discotic liquid crystal nanocomposites are less studied. In the present experimental work, we have studied the effect of ferroelectric (BaTiO_{3}) nanoparticles on a room temperature discotic liquid crystalline material, namely 1,5-dihydroxy-2,3,6,7-tetrakis(3,7-dimethyloctyloxy)-9,10-anthraquinone. We investigated the physical properties of low concentration ferroelectric nanoparticle dispersed discotic columnar structure, using calorimetric, optical, x-ray diffraction, and dielectric spectroscopy tools. Results show that inclusion of ferroelectric nanoparticles in the discotic matrix consolidates the stability of the columnar matrix of the Col_{h} phase by virtue of their ferroic nature. An enhancement in charge carrier conductivity by several orders of magnitude at ambient conditions has been observed which makes such systems highly appropriate for one-dimensional conductors. Low concentration of BaTiO_{3} nanoparticles substantially enhanced permittivity of the system also. A molecular relaxation mode has been observed in the middle frequency range of the dielectric spectra. Enhancement of these important parameters could be possible due to the ferroelectric nature of the dispersed nanoparticles.
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Affiliation(s)
- Rahul Uttam
- Centre of Material Sciences, University of Allahabad, Prayagraj 211002, India
| | - Sandeep Kumar
- Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bengaluru 560080, India.,Department of Chemistry, Nitte Meenakshi Institute of Technology, Bengaluru 560064, India
| | - Ravindra Dhar
- Centre of Material Sciences, University of Allahabad, Prayagraj 211002, India
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Abstract
Abstract
The integration of nanoparticles with magnetic, ferroelectric or semiconducting properties into liquid crystals (LCs) has attracted great interest both for fundamental investigations and for technological applications. Here, an overview of hybrid materials based on magnetic nanoparticles (MNPs) and thermotropic LCs is given. After a general introduction to thermotropic LCs and LC-MNP hybrid materials, various preparation methods established by us are presented. The synthesis of shape-(an)isotropic MNPs, their functionalization by tailored (pro)mesogenic ligands with linear or dendritic structures and their integration into LC hosts are discussed. The characterization of the MNPs, (pro)mesogenic ligands and resulting MNP-LC hybrid materials is described to show the influence of MNP functionalization on the MNP-LC interactions including aspects such as colloidal stability and structuring in the LC host. Overall, we show that the physical properties of the hybrid material are significantly influenced not only by the MNPs (i.e., their size, shape and composition) but also by their surface properties (i.e., the structure of the (pro)mesogenic ligands).
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Affiliation(s)
- Martin Hähsler
- Institute of Catalysis Research and Technology , Karlsruhe Institute of Technology , Postfach 3640 , 76021 Karlsruhe , Germany
- Institute of Inorganic Chemistry , Ruprecht-Karls University Heidelberg , Im Neuenheimer Feld 270 , 69120 Heidelberg , Germany
| | - Ingo Appel
- Institute of Catalysis Research and Technology , Karlsruhe Institute of Technology , Postfach 3640 , 76021 Karlsruhe , Germany
- Institute of Inorganic Chemistry , Ruprecht-Karls University Heidelberg , Im Neuenheimer Feld 270 , 69120 Heidelberg , Germany
| | - Silke Behrens
- Institute of Catalysis Research and Technology , Karlsruhe Institute of Technology , Postfach 3640 , 76021 Karlsruhe , Germany
- Institute of Inorganic Chemistry , Ruprecht-Karls University Heidelberg , Im Neuenheimer Feld 270 , 69120 Heidelberg , Germany
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Debnath A, Mandal PK, Sarma A, Gutowski O. Effect of silver nanoparticle doping on the physicochemical properties of a room temperature ferroelectric liquid crystal mixture. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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25
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Prakash J, Parveen A, Mishra YK, Kaushik A. Nanotechnology-assisted liquid crystals-based biosensors: Towards fundamental to advanced applications. Biosens Bioelectron 2020; 168:112562. [DOI: 10.1016/j.bios.2020.112562] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 06/09/2020] [Accepted: 08/24/2020] [Indexed: 02/06/2023]
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27
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Shen Y, Dierking I. Dynamic dissipative solitons in nematics with positive anisotropies. SOFT MATTER 2020; 16:5325-5333. [PMID: 32469028 DOI: 10.1039/d0sm00676a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electric field induced instabilities of nematic molecules are of importance for both fundamental science and practical applications. Complex electro-hydrodynamic (EHD) effects such as electro-convection, fingerprint textures, spatiotemporal chaos, and solitons in nematics have been broadly investigated and generated much attention. In this work, dissipative solitons as a novel EHD phenomenon are realized in nematics with positive anisotropies, presumably for the first time. Unlike the ones reported recently in nematics with negative anisotropies whose formation and dynamics are mainly attributed to the flexoelectric and electro-convection effects, the solitons discussed here arise from the nonlinear coupling between the director field and the isotropic flow induced by ion motion. The structure and dynamics of the solitons are demonstrated and the influences of chirality, azimuthal anchoring and ion concentration are also investigated. Finally, we show that the propagation trajectory of solitons can be manipulated by patterned photoalignment and micro-particles can be trapped by them as vehicles for micro-cargo transport.
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Affiliation(s)
- Yuan Shen
- Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - Ingo Dierking
- Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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Liquid Crystalline Copolymers Containing Sulfonic and Light-Responsive Groups: From Molecular Design to Conductivity. Molecules 2020; 25:molecules25112579. [PMID: 32498249 PMCID: PMC7321325 DOI: 10.3390/molecules25112579] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 05/26/2020] [Accepted: 05/27/2020] [Indexed: 11/27/2022] Open
Abstract
In the search for novel smart multifunctional liquid crystalline materials, we report the synthesis, thermal and structural characterisation, and the conductivity, of a set of new block and statistical copolymers, containing light-responsive mesogenic groups (MeOAzB), polar sulfonic acids (AMPS), and methyl(methacrylate) groups (MMA). By using a cascade of reversible addition-fragmentation chain polymerisations, RAFT, we have tailored different side-chain polymeric structures by controlling monomer composition (MeOAzB/AMPS/MMA) and configuration. We have yielded simultaneous liquid crystalline behaviour and appreciable conductivity in polymers with low concentrations of polar acid groups, by the formation of smectic phases in narrow aggregates. The light-responsiveness of the polymers, via reversible trans-to-cis photoisomerization of azobenzene groups, and the local activation of conductivity at relatively low temperatures, opens the possibility to prepare polymer electrolytes for energy conversion and storage, whose conductivity could be controlled and optimised by external stimuli, including light irradiation.
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Sandhya K, Pushpavathi N, Rao DS, Prasad SK. Dielectric and electro optic studies in the vicinity of the transition between two tilted hexatic phases of a ZnO-liquid crystal nanocomposite. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112508] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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30
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Lombardo D, Calandra P, Pasqua L, Magazù S. Self-assembly of Organic Nanomaterials and Biomaterials: The Bottom-Up Approach for Functional Nanostructures Formation and Advanced Applications. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E1048. [PMID: 32110877 PMCID: PMC7084717 DOI: 10.3390/ma13051048] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 02/17/2020] [Accepted: 02/20/2020] [Indexed: 12/11/2022]
Abstract
In this paper, we survey recent advances in the self-assembly processes of novel functional platforms for nanomaterials and biomaterials applications. We provide an organized overview, by analyzing the main factors that influence the formation of organic nanostructured systems, while putting into evidence the main challenges, limitations and emerging approaches in the various fields of nanotechology and biotechnology. We outline how the building blocks properties, the mutual and cooperative interactions, as well as the initial spatial configuration (and environment conditions) play a fundamental role in the construction of efficient nanostructured materials with desired functional properties. The insertion of functional endgroups (such as polymers, peptides or DNA) within the nanostructured units has enormously increased the complexity of morphologies and functions that can be designed in the fabrication of bio-inspired materials capable of mimicking biological activity. However, unwanted or uncontrollable effects originating from unexpected thermodynamic perturbations or complex cooperative interactions interfere at the molecular level with the designed assembly process. Correction and harmonization of unwanted processes is one of the major challenges of the next decades and requires a deeper knowledge and understanding of the key factors that drive the formation of nanomaterials. Self-assembly of nanomaterials still remains a central topic of current research located at the interface between material science and engineering, biotechnology and nanomedicine, and it will continue to stimulate the renewed interest of biologist, physicists and materials engineers by combining the principles of molecular self-assembly with the concept of supramolecular chemistry.
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Affiliation(s)
- Domenico Lombardo
- Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico-Fisici, 98158 Messina, Italy
| | - Pietro Calandra
- Consiglio Nazionale delle Ricerche, Istituto Studio Materiali Nanostrutturati, 00015 Roma, Italy;
| | - Luigi Pasqua
- Department of Environmental and Chemical Engineering, University of Calabria, 87036 Rende, Italy;
| | - Salvatore Magazù
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università di Messina, 98166 Messina, Italy;
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On the Analogy between Electrolytes and Ion-Generating Nanomaterials in Liquid Crystals. NANOMATERIALS 2020; 10:nano10030403. [PMID: 32106491 PMCID: PMC7152844 DOI: 10.3390/nano10030403] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/20/2022]
Abstract
Nanomaterials in liquid crystals are a hot topic of contemporary liquid crystal research. An understanding of the possible effects of nanodopants on the properties of liquid crystals is critical for the development of novel mesogenic materials with improved functionalities. This paper focuses on the electrical behavior of contaminated nanoparticles in liquid crystals. More specifically, an analogy between electrolytes and ion-generating nanomaterials in liquid crystals is established. The physical consequences of this analogy are analyzed. Under comparable conditions, the number of ions generated by nanomaterials in liquid crystals can be substantially greater than the number of ions generated by electrolytes of similar concentration.
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33
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Super Stability of Ag Nanoparticle in Crystalline Lamellar (Lc) Liquid Crystal Matrix at Different pH Environment. Symmetry (Basel) 2019. [DOI: 10.3390/sym12010031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The symmetry concept in this paper is related to the natural self-assembly of noble metal nanoparticles in the long range periodic structure of liquid crystal (LC). The current study deliberates the effect of pH on the stability of nanoparticles (NPs) in the lamellar phase of a lyotropic LC environment. The LC was prepared by the mass ratio 0.33:0.22:0.45 for (HDTABr):1-pentanol:water. The LC containing silver nanoparticles (AgNPs) was prepared by replacing the water with Ag solution. The AgNPs were produced by the in situ preparation method in LC. The solution of AgNPs-LC was varied at different pH. The absorption intensities were determined by using ultra-violet spectroscopy (UV-vis). The surface potential and hydrodynamic particle size were determined by using Zeta-potential (measurements). The surface enhanced Raman spectroscopy (SERS) was carried out to enhance the Raman signals of 4-aminobenzenethiol (4-ABT) deposited onto AgNPs as substrate. It is found that all characterizations exhibited super stability for AgNPs dispersed in LC at pH = 3 to 12 with the optimum stability at pH = 5–6. The remarkable stability of NPs is an important indicator of the various applications in nanotechnology and nanoscience fields.
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34
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Shen Y, Dierking I. Annihilation dynamics of topological defects induced by microparticles in nematic liquid crystals. SOFT MATTER 2019; 15:8749-8757. [PMID: 31588472 DOI: 10.1039/c9sm01710k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The annihilation dynamics of s = ±1 topological defects with and without microparticles in a nematic liquid crystal were investigated and compared. The microparticle with a homeotropic surface anchoring can act as a s = +1 defect and produce a corresponding s = -1 defect nearby. Both of them attract and move towards each other. The speed of the positive defect induced by the microparticle is much slower than that of the negative defect, contrary to the situation without particles. The effects of electric field strength and frequency, particle size, the confining cell gap, and temperature were systematically investigated. The study shows that the dynamics of the annihilation process is related to a complex interplay between elastic attractions, viscous drag forces, backflow effects, director configurations and cell confinement.
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Affiliation(s)
- Yuan Shen
- Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - Ingo Dierking
- Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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