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Raczyńska V, Górny K, Raczyński P, Dendzik Z, Starzonek S. Two-dimensional phases of confined 5-cyano-biphenyl: Computer simulation study. Phys Rev E 2023; 108:034702. [PMID: 37849085 DOI: 10.1103/physreve.108.034702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 08/25/2023] [Indexed: 10/19/2023]
Abstract
The properties of composites of mesogens and two-dimensional (2D) materials are of great interest due to their practical applications in flexible displays, optoelectronics, microelectronics, and novel nanodevices. The properties of such composites are very complex and strongly depend on the interactions between the host material and the mesogen filling. We have performed molecular dynamics simulations for 4-cyano-4^{'}-pentylbiphenyl embedded between graphene and hexagonal 2D boron nitride layers. The structural and dynamical properties of such systems were investigated in terms of the order parameters, density profiles, mean square displacement, and autocorrelation function of the single-molecule dipole moment. Our simulations have shown that the mesogenic molecules form highly stable ordered layered structures and that their dynamics are strongly related to the structural properties. We have investigated not only the effects of the polarization of the host material, but also the effects of the spatial repetition of such composites by using two models of mesogens embedded in 2D layers: the direct sheet and the structure formed by multiplying a single unit of the composite in the direction perpendicular to the substrate surface.
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Affiliation(s)
- Violetta Raczyńska
- Faculty of Science and Technology, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - Krzysztof Górny
- Faculty of Science and Technology, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - Przemysław Raczyński
- Faculty of Science and Technology, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - Zbigniew Dendzik
- Faculty of Science and Technology, University of Silesia in Katowice, ul. 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland
| | - Szymon Starzonek
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, 1000 Ljubljana, Slovenia
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Zhang Z, Bolshakov A, Han J, Zhu J, Yang KL. Electrospun Core-Sheath Fibers with a Uniformly Aligned Polymer Network Liquid Crystal (PNLC). ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 36916499 DOI: 10.1021/acsami.2c23065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Electrospun polymer-liquid crystal (PLC) fibers have potential applications such as wearable sensors and adaptive textiles because of their rapid response and high flexibility. However, existing PLC fibers only have a narrow responsive range and poor resistance to heat and chemicals. Herein, a new type of PLC fiber is prepared by using a coaxial electrospinning process. The core solution is 4'-pentyl-4-biphenylcarbonitrile (5CB), and the sheath solution is a mixture containing 13 wt % PVP and 10 wt % reactive mesogen (RM). After UV exposure of the fibers, 5CB in the core and RM diffusing from the core are cross-linked into an LC polymer. The fibers have a highly uniform morphology with an average diameter of 3.2 ± 0.5 μm, and mesogens inside the fibers align unidirectionally with the long axis of the fibers. The fibers show a broad phase-transition temperature range between 13.5 and 155.5 °C and have a response time of less than 10 s. The temperature range can also be controlled by adjusting components in the electrospun fibers and UV exposure time. The core-sheath fibers prepared in such a manner exhibit excellent heat and chemical resistance with reversible optical responses. Moreover, when the fibers are exposed to volatile organic compounds (VOCs) such as toluene, the fibers show a rapid optical response to toluene vapor within 25 s. This study demonstrates that the fibers are potentially useful for preparing flexible temperature and chemical sensors.
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Affiliation(s)
- Zhibo Zhang
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin 150080, P. R. China
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore, Singapore
| | - Andrey Bolshakov
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin 150080, P. R. China
| | - Jiecai Han
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin 150080, P. R. China
| | - Jiaqi Zhu
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin 150080, P. R. China
| | - Kun-Lin Yang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore, Singapore
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Fryń P, Lalik S, Bogdanowicz KA, Górska N, Iwan A, Marzec M. Degradation of hybrid material l,d-PLA : 5CB : SWCN under the influence of neutral, acidic, and alkaline environments. RSC Adv 2023; 13:3792-3806. [PMID: 36756553 PMCID: PMC9890945 DOI: 10.1039/d2ra05350k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 01/10/2023] [Indexed: 01/27/2023] Open
Abstract
The aim of the study was to investigate the influence of the environment's pH on the degradation of the layers of the ternary composite l,d-PLA : 5CB : SWCN (10 : 1 : 0.5, w/w/w), where l,d-PLA (poly(lactic acid)) is a biodegradable polymer, 5CB is a well-known liquid crystal (4'-pentyl-4-biphenylcarbonitrile), and SWCN are single-walled carbon nanotubes. For this purpose, the samples were stored in air, distilled water, and solutions of 0.1 M NaOH and 0.1 M HCl, for up to 62 days. Using differential scanning calorimetry, atomic force microscopy, and infra-red spectroscopy methods it was observed that for both neat l,d-PLA and composite layers there was a poor degradation process after the storage under standard air conditions, distilled water, and 0.1 M HCl solution, while the erosion of the surface layer kept in 0.1 M NaOH solution was revealed just after 6 days. The longer storage in 0.1 M NaOH solution resulted in complete degradation of the l,d-PLA polymer layer, while the composite layer survived for up to 62 days. The solubilization of the polymeric l,d-PLA matrix in the composite after 62 days was so severe that it resulted in the vanishing of thermal effects on the DSC curve except for one that was probably connected with the glass transition of the residual quantity of the polymer that remained in the layer or the isotropisation of 5CB. As a result, we have shown that admixtures of 5CB and SWCN accelerate the degradation of l,d-PLA in the composite layer due to the hydrophilic/hydrophobic interface in the layer and act as plasticizers. The mechanism of the degradation process is also discussed.
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Affiliation(s)
- Patryk Fryń
- Institute of Physics, Jagiellonian University Łojasiewicza 11 30-348 Kraków Poland
| | - Sebastian Lalik
- Institute of Physics, Jagiellonian University Łojasiewicza 11 30-348 Kraków Poland
| | | | - Natalia Górska
- Faculty of Chemistry, Jagiellonian University Gronostajowa 2 30-387 Kraków Poland
| | - Agnieszka Iwan
- Faculty of Security and Safety Research, General Tadeusz Kościuszko Military University of Land Forces Czajkowskiego 109 51-147 Wrocław Poland
| | - Monika Marzec
- Institute of Physics, Jagiellonian University Łojasiewicza 11 30-348 Kraków Poland
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Chiang LY, Wang CT, Pappert S, Yu PKL. Silicon-organic hybrid thermo-optic switch based on a slot waveguide directional coupler. OPTICS LETTERS 2022; 47:3940-3943. [PMID: 35913353 DOI: 10.1364/ol.467858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
We propose and demonstrate a passively biased 2 × 2 thermo-optic switch with high power efficiency and fast response time. The device benefits from the highly concentrated optical field of a slot waveguide mode and the strong thermo-optic effect of a nematic liquid crystal (NLC) cladding. The NLC fills the nano-slot region and is aligned by the subwavelength grating inside. The measured power consumption and thermal time constant are 0.58 mW and 11.8 µs, respectively, corresponding to a figure-of-merit of 6.8 mW µs. The proposed silicon-organic hybrid device provides a new solution to design thermo-optic actuators having low power consumption and fast operation speed.
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Dhara P, Mukherjee R. Phase separation and dewetting of polymer dispersed liquid crystal (PDLC) thin films on flat and patterned substrates. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Wu PC, Pai CP, Lee MJ, Lee W. A Single-Substrate Biosensor with Spin-Coated Liquid Crystal Film for Simple, Sensitive and Label-Free Protein Detection. BIOSENSORS 2021; 11:374. [PMID: 34677330 PMCID: PMC8533856 DOI: 10.3390/bios11100374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/25/2021] [Accepted: 10/03/2021] [Indexed: 12/31/2022]
Abstract
A liquid crystal (LC)-based single-substrate biosensor was developed by spin-coating an LC thin film on a dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP)-decorated glass slide. Compared with the conventional sandwiched cell configuration, the simplified procedure for the preparation of an LC film allows the film thickness to be precisely controlled by adjusting the spin rate, thus eliminating personal errors involved in LC cell assembly. The limit of detection (LOD) for bovine serum albumin (BSA) was lowered from 10-5 g/mL with a 4.2-μm-thick sandwiched cell of the commercial LC E7 to 10-7 g/mL with a 4.2-μm-thick spin-coated E7 film and further to 10-8 g/mL by reducing the E7 film thickness to 3.4 μm. Moreover, by exploiting the LC film of the highly birefringent nematic LC HDN in the immunodetection of the cancer biomarker CA125, an LOD comparable to that determined with a sandwiched HDN cell was achieved at 10-8 g/mL CA125 using a capture antibody concentration an order of magnitude lower than that in the LC cell. Our results suggest that employing spin-coated LC film instead of conventional sandwiched LC cell provides a more reliable, reproducible, and cost-effective single-substrate platform, allowing simple fabrication of an LC-based biosensor for sensitive and label-free protein detection and immunoassay.
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Affiliation(s)
- Po-Chang Wu
- Institute of Imaging and Biomedical Photonics, College of Photonics, National Yang Ming Chiao Tung University, Guiren Dist., Tainan 711010, Taiwan; (P.-C.W.); (C.-P.P.)
| | - Chao-Ping Pai
- Institute of Imaging and Biomedical Photonics, College of Photonics, National Yang Ming Chiao Tung University, Guiren Dist., Tainan 711010, Taiwan; (P.-C.W.); (C.-P.P.)
| | - Mon-Juan Lee
- Department of Bioscience Technology, Chang Jung Christian University, Guiren Dist., Tainan 711301, Taiwan
- Department of Medical Science Industries, Chang Jung Christian University, Guiren Dist., Tainan 711301, Taiwan
| | - Wei Lee
- Institute of Imaging and Biomedical Photonics, College of Photonics, National Yang Ming Chiao Tung University, Guiren Dist., Tainan 711010, Taiwan; (P.-C.W.); (C.-P.P.)
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Shimada R, Urakawa O, Inoue T, Watanabe H. Phase equilibrium and dielectric relaxation in mixture of 5CB with dilute dimethyl phthalate: effect of coupling between orientation and composition fluctuations on molecular dynamics in isotropic one-phase state. SOFT MATTER 2021; 17:6259-6272. [PMID: 34124720 DOI: 10.1039/d1sm00496d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Phase equilibrium and dielectric relaxation were examined for mixtures of liquid-crystalline (LC)-forming 4-cyano-4'-pentylbiphenyl (5CB) with dilute dimethyl phthalate (DMP). The mixtures were in an isotropic one-phase state at high temperatures T but were separated into nematic and isotropic phases at low T < TIN (isotropic-to-nematic transition temperature), and the isotropic phase disappeared and a nematic one-phase state was realized on a further decrease of T below another transition temperature . These TIN and data (phase diagram) were described considerably well by a simple model of free energy contributed from a Flory-Huggins type mixing entropy (no enthalpic contribution) and a Landau-de Gennes type nematic interaction. This success of the model, not expected for ordinary (not LC-forming) components exhibiting enthalpically-driven phase separation, suggested that the phase separation in the DMP/5CB mixtures was triggered by the nematic transition of 5CB (possibly governed by the packing entropy) and thus the orientation fluctuation of 5CB molecules was coupled with the composition fluctuation. This coupling was expected to affect the dielectric relaxation detecting the rotational dynamics of 5CB molecules, the major component in the mixtures. This expectation was examined for a representative mixture having the DMP content of wDMP = 3.1 wt% and TIN ≅ 27.0 °C. In a high-T asymptote (T > TIN + 10 °C), the dielectric relaxation of this mixture was close to that of pure 5CB, which suggested no significant effect of the above coupling on 5CB dynamics in the mixture at such high T. Nevertheless, in a significantly wide range of T between TIN and TIN + 10 °C, the dielectric relaxation time τε of the isotropic one-phase mixture increased on cooling much more significantly compared to τε in that high-T asymptote. The kinematic viscosity ν of the mixture exhibited a qualitatively similar increase in the same range of T, but this increase was weaker than that of τε. This difference between the dielectric τε and the rheological ν was attributed to coupling of the orientation and the composition fluctuations mentioned above. Namely, the composition fluctuation enhances the orientation fluctuation in the mixture thereby providing τε (reflecting the orientation fluctuation) with an extra increase. Pure 5CB exhibited similar increases of τε and ν (stronger for the former) but only in a close vicinity of (within 2-3 °C), because the orientation fluctuation in pure 5CB is coupled with the density fluctuation, not with the composition fluctuation being absent in the pure 5CB system. This behavior of pure 5CB in turn suggests an importance of the coupling of orientation and composition fluctuations in the mixture.
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Affiliation(s)
- Ryoko Shimada
- Department of Mathematical and Physical Sciences, Japan Women's University, Bunkyo-ku, Tokyo 112-8681, Japan.
| | - Osamu Urakawa
- Department of Macromolecular Science, Faculty of Science, Osaka University, Toyonaka, Osaka 560-0041, Japan.
| | - Tadashi Inoue
- Department of Macromolecular Science, Faculty of Science, Osaka University, Toyonaka, Osaka 560-0041, Japan.
| | - Hiroshi Watanabe
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
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Dhara P, Mukherjee R. Influence of Substrate Surface Properties on Spin Dewetting, Texture, and Phase Transitions of 5CB Liquid-Crystal Thin Films. J Phys Chem B 2020; 124:1293-1300. [DOI: 10.1021/acs.jpcb.9b11569] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Palash Dhara
- Instability and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Rabibrata Mukherjee
- Instability and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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