1
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Zhou Z, Zhang X, Shin Y, Halder S, Hu L, Yang DK. Effect of Polymerization on Chirality in Cholesteric Liquid Crystals. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00942] [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]
Affiliation(s)
- Ziyuan Zhou
- Chemical Physics Interdisciplinary Program, Department of Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, United States
| | - Xinfang Zhang
- Chemical Physics Interdisciplinary Program, Department of Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, United States
| | - Yunho Shin
- Chemical Physics Interdisciplinary Program, Department of Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, United States
| | - Suman Halder
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
| | - Lang Hu
- Chemical Physics Interdisciplinary Program, Department of Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, United States
| | - Deng-Ke Yang
- Chemical Physics Interdisciplinary Program, Department of Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, United States
- Department of Physics, Kent State University, Kent, Ohio 44242, United States
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2
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Sheng M, Li J, Jiang X, Wang C, Li J, Zhang L, Fu S. Biomimetic Solid-Liquid Transition Structural Dye-Doped Liquid Crystal/Phase-Change-Material Microcapsules Designed for Wearable Bistable Electrochromic Fabric. ACS APPLIED MATERIALS & INTERFACES 2021; 13:33282-33290. [PMID: 34227793 DOI: 10.1021/acsami.1c08135] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A novel polymer microcapsule-filled dye-doped liquid crystal (DDLC) and phase-change material (PCM) system inspired by biological materials was first proposed, which was further encapsulated into a calcium alginate substrate by wet spinning for making an electrochromic fiber with both bistable electric-optical capability and knitting characteristics. Results show that the optical appearance of the optimized microcapsules and fiber can be reversibly changed between colored and colorless states according to the electric field by switching the DDLCs between isotropic (I) and anisotropic (A) states. Moreover, both I and A states can remain stable for more than 1 week after removing the electric field, due to the synergy of the greatly increased spatial hindrance of the PCM with core loading of 22.58% and the confinement effect from the polymer microcapsule shell material. Aside from the long-term optical stability, the high content of the densely packed DDLCs also endows the electrochromic fiber with a satisfactory driving voltage of 9.7 V, which is below the human safe voltage, showing great potential in a wide range of applications, such as flexible displays, energy-saving smart windows, and wearable advanced textiles.
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Affiliation(s)
- Mingfei Sheng
- Key Laboratory of Science & Technology of Eco-Textile, Jiangnan University, Ministry of Education, Wuxi, Jiangsu 214122, China
| | - Jingjing Li
- The First Scientific Research Institute of Wuxi, Wuxi, Jiangsu 214122, China
| | - Xiaojun Jiang
- The First Scientific Research Institute of Wuxi, Wuxi, Jiangsu 214122, China
| | - Chengcheng Wang
- Key Laboratory of Science & Technology of Eco-Textile, Jiangnan University, Ministry of Education, Wuxi, Jiangsu 214122, China
| | - Jiashuang Li
- Key Laboratory of Science & Technology of Eco-Textile, Jiangnan University, Ministry of Education, Wuxi, Jiangsu 214122, China
| | - Liping Zhang
- Key Laboratory of Science & Technology of Eco-Textile, Jiangnan University, Ministry of Education, Wuxi, Jiangsu 214122, China
| | - Shaohai Fu
- Key Laboratory of Science & Technology of Eco-Textile, Jiangnan University, Ministry of Education, Wuxi, Jiangsu 214122, China
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3
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Yamaguchi R, Inoue K. Electrical and Optical Model of Reverse Mode Liquid Crystal Cells with Low Driving Voltage. J PHOTOPOLYM SCI TEC 2021. [DOI: 10.2494/photopolymer.34.315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Rumiko Yamaguchi
- Cooperative Major in Life Cycle Design Engineering Graduate School of Engineering Science, Akita University
| | - Koichi Inoue
- Cooperative Major in Life Cycle Design Engineering Graduate School of Engineering Science, Akita University
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4
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Zhao W, de Haan LT, Broer DJ, Zhang Y, Lv P, Zhou G. Photopolymerization-enforced stratification in liquid crystal materials. Prog Polym Sci 2021. [DOI: 10.1016/j.progpolymsci.2021.101365] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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5
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Effect of Ion Concentration on the Electro-Optic Response in Polymer-Stabilized Cholesteric Liquid Crystals. CRYSTALS 2020. [DOI: 10.3390/cryst11010007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have previously reported that the application of a DC field can adjust the position and/or bandwidth of the selective reflection notch in polymer-stabilized cholesteric liquid crystals (PSCLCs). The proposed mechanism of these electro-optic (EO) response is ion-facilitated electromechanical deformation of the polymer stabilizing network. Accordingly, the concentration of ions trapped within the polymer network should considerably influence the EO response of PSCLC. Our prior studies have indicated that photoinitiators can increase ion density in PSCLC by an order of magnitude. Here, we isolate the contribution of ionic impurities associated with liquid crystal monomers (LCMs) by utilizing initiator-less polymerization. PSCLCs prepared with LCM with low ion concentration show bandwidth broadening of the reflection band whereas PSCLCs prepared with LCM with high ion concentration exhibit a red shifting tuning of the reflection band. The extent of the tuning or bandwidth broadening of the CLC reflection band depends on the concentration of LCMs and the chirality of the LCM.
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Hu X, Zhang X, Yang W, Jiang X, Jiang X, Haan LT, Yuan D, Zhao W, Zheng N, Jin M, Shui L, Schenning APHJ, Zhou G. Stable and scalable smart window based on polymer stabilized liquid crystals. J Appl Polym Sci 2020. [DOI: 10.1002/app.48917] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Xiaowen Hu
- SCNU‐TUE Joint Lab of Device Integrated Responsive Materials (DIRM) and National Center for International Research on Green Optoelectronics, South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Xinmin Zhang
- SCNU‐TUE Joint Lab of Device Integrated Responsive Materials (DIRM) and National Center for International Research on Green Optoelectronics, South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Wenmin Yang
- SCNU‐TUE Joint Lab of Device Integrated Responsive Materials (DIRM) and National Center for International Research on Green Optoelectronics, South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Xiao‐Fang Jiang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper DisplaysSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Xinshuai Jiang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper DisplaysSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Laurens T. Haan
- SCNU‐TUE Joint Lab of Device Integrated Responsive Materials (DIRM) and National Center for International Research on Green Optoelectronics, South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Dong Yuan
- SCNU‐TUE Joint Lab of Device Integrated Responsive Materials (DIRM) and National Center for International Research on Green Optoelectronics, South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Wei Zhao
- SCNU‐TUE Joint Lab of Device Integrated Responsive Materials (DIRM) and National Center for International Research on Green Optoelectronics, South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Nan Zheng
- State Key Laboratory of Luminescent Materials and DevicesSouth China University of Technology Guangzhou 510640 People's Republic of China
| | - Mingliang Jin
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper DisplaysSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Lingling Shui
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper DisplaysSouth China Normal University Guangzhou 510006 People's Republic of China
| | - Albertus P. H. J. Schenning
- Chemical Engineering and Chemistry, Functional Organic Materials and DevicesEindhoven University of Technology 5600 MB Eindhoven The Netherlands
| | - Guofu Zhou
- SCNU‐TUE Joint Lab of Device Integrated Responsive Materials (DIRM) and National Center for International Research on Green Optoelectronics, South China Academy of Advanced OptoelectronicsSouth China Normal University Guangzhou 510006 People's Republic of China
- Shenzhen Guohua Optoelectronics Technology Co., Ltd. Shenzhen 518110 People's Republic of China
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7
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Sun H, Xie Z, Ju C, Hu X, Yuan D, Zhao W, Shui L, Zhou G. Dye-Doped Electrically Smart Windows Based on Polymer-Stabilized Liquid Crystal. Polymers (Basel) 2019; 11:polym11040694. [PMID: 30995763 PMCID: PMC6523582 DOI: 10.3390/polym11040694] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/10/2019] [Accepted: 04/12/2019] [Indexed: 11/30/2022] Open
Abstract
Here we report the fabrication of dye-doped polymer-stabilized liquid crystals (PSLC)-based smart windows. The effect of dye doping on PSLC contrast was investigated. Non-dichroic dye tints the PSLC sample in both off- and on-state, which is not beneficial for increasing its off/on contrast. The sample doped with dichroic dye shows a slight color in the off-state and strong color in the on-state, resulting in an enhanced contrast, which attributed to orientation dependent absorption of dichroic dyes. Furthermore, we blended non-dichroic dye and dichroic dye who have complementary absorption together into PSLC mixture. The sample is almost colorless in the off-state due to the subtractive process, while colored in the on-state. The contrast is further enhanced. The results show that the proposed multi-dye-doped PSLC device has high visual contrast and fast response time, making it attractive for applications in light management and architectural aesthetics.
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Affiliation(s)
- Haitao Sun
- SCNU-TUE Joint Lab of Device Integrated Responsive Materials (DIRM), National Center for International Research on Green Optoelectronics, South China Normal University, No 378, West Waihuan Road, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Zuoping Xie
- SCNU-TUE Joint Lab of Device Integrated Responsive Materials (DIRM), National Center for International Research on Green Optoelectronics, South China Normal University, No 378, West Waihuan Road, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Chun Ju
- SCNU-TUE Joint Lab of Device Integrated Responsive Materials (DIRM), National Center for International Research on Green Optoelectronics, South China Normal University, No 378, West Waihuan Road, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Xiaowen Hu
- SCNU-TUE Joint Lab of Device Integrated Responsive Materials (DIRM), National Center for International Research on Green Optoelectronics, South China Normal University, No 378, West Waihuan Road, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Dong Yuan
- SCNU-TUE Joint Lab of Device Integrated Responsive Materials (DIRM), National Center for International Research on Green Optoelectronics, South China Normal University, No 378, West Waihuan Road, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Wei Zhao
- SCNU-TUE Joint Lab of Device Integrated Responsive Materials (DIRM), National Center for International Research on Green Optoelectronics, South China Normal University, No 378, West Waihuan Road, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Lingling Shui
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
| | - Guofu Zhou
- SCNU-TUE Joint Lab of Device Integrated Responsive Materials (DIRM), National Center for International Research on Green Optoelectronics, South China Normal University, No 378, West Waihuan Road, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen 518110, China.
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8
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Nemati H, Liu S, Moheghi A, Tondiglia VP, Lee KM, Bunning TJ, Yang DK. Enhanced reflection band broadening in polymer stabilized cholesteric liquid crystals with negative dielectric anisotropy. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.02.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Wang J, McGinty C, Reich R, Finnemeyer V, Clark H, Berry S, Bos P. Process for a Reactive Monomer Alignment Layer for Liquid Crystals Formed on an Azodye Sublayer. MATERIALS 2018; 11:ma11071195. [PMID: 30002302 PMCID: PMC6073623 DOI: 10.3390/ma11071195] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 12/05/2022]
Abstract
In this work, the detailed studies of surface polymerization stabilizing liquid crystal formed on an azodye sublayer are presented. The surface localized stabilization is obtained by free-radical polymerization of a dilute solution of a bi-functional reactive monomer (RM) in a liquid crystal (LC) solvent. To optimize the process for surface localized stabilization, we investigate the effects of several process parameters including RM concentration in LC hosts, the types of materials (either RM or LC), the photo-initiator (PI) concentration, ultra-violet (UV) polymerization intensity, and the UV curing temperature. The quality of surface localized stabilization is characterized and/or evaluated by optical microscopy, electro-optical behavior (transmission/voltage curve), the life test, and photo-bleaching. Our results show that, by carefully selecting materials, formulating mixtures, and controlling the polymerizing variables, the RM polymerization can be realized either at the surface or through the bulk. Overall, the combination of surface localized stabilization and photo-alignment offers an elegant and dynamic solution for controlling the alignment for LC, which could play a profound role in almost all liquid crystal optical devices.
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Affiliation(s)
- Junren Wang
- Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
| | - Colin McGinty
- Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
| | - Robert Reich
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA 02421, USA.
| | - Valerie Finnemeyer
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA 02421, USA.
| | - Harry Clark
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA 02421, USA.
| | - Shaun Berry
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA 02421, USA.
| | - Philip Bos
- Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
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10
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Chien CY, Sung PK, Sheu CR. Photo-Polymerization in Chiral Dopant Liquid Crystal Cells via Holographic Exposure to Fabricate Polarization-Independent Phase Modulator with Fast Optical Response. Polymers (Basel) 2018; 10:E315. [PMID: 30966350 PMCID: PMC6414867 DOI: 10.3390/polym10030315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 03/12/2018] [Accepted: 03/12/2018] [Indexed: 11/16/2022] Open
Abstract
Small liquid crystal domains with random director distributions were obtained to show novel optical isotropy using a holographic exposure processes to treat chiral dopant liquid crystal cells in the isotropic phase (i.e., polymer-stabilized isotropic liquid crystal cells). The cells used to fabricate phase modulators showed unique performances, including low light scattering, polarization-independence, and fast optical response. Furthermore, an extra fluoro-surfactant dopant in cells showed that the phase modulators retained their performance but with considerable reduction of operating voltages, from 180 Vrms to 100 Vrms.
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Affiliation(s)
- Chun-Yu Chien
- Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan.
| | - Pin-Kuan Sung
- Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan.
| | - Chia-Rong Sheu
- Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan.
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11
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Yu M, Yang H, Yang DK. Stabilized electrically induced Helfrich deformation and enhanced color tuning in cholesteric liquid crystals. SOFT MATTER 2017; 13:8728-8735. [PMID: 29149232 DOI: 10.1039/c7sm01997a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
When subjected to an AC electric field perpendicular to its layers, the cholesteric planar state may undergo a periodic layer undulation, known as the Helfrich deformation, which generates a color change of the reflected light. The Helfrich deformation of regular cholesteric liquid crystals is, however, unstable and easily taken over by the focal conic state, and thus the color tuning range is narrow. We demonstrated that the Helfrich deformation can be stabilized in a large electric field region by doping a bent dimer with an anomalously small bend elastic constant and dispersing a small amount of polymer network. By varying the dimer concentration, we were able to systematically change the bend elastic constant and thus verify the theoretical prediction of the undulation threshold electric field and periodicity. We also achieved reflectance tuning with electric field less than 2 V μm-1 and color tuning covering the entire visible light region with electric field as low as 4 V μm-1.
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Affiliation(s)
- Meina Yu
- Department of Materials Science and Engineering, College of Engineering, and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing 100871, P. R. China
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12
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Yu M, Wang L, Nemati H, Yang H, Bunning T, Yang DK. Effects of polymer network on electrically induced reflection band broadening of cholesteric liquid crystals. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/polb.24317] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Meina Yu
- Department of Materials Science and Engineering; College of Engineering, and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University; Beijing 100871 People's Republic of China
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University; Kent Ohio 44242
| | - Ling Wang
- Department of Materials Science and Engineering; College of Engineering, and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University; Beijing 100871 People's Republic of China
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University; Kent Ohio 44242
| | - Hossein Nemati
- Air Force Research Laboratory; Materials and Manufacturing Directorate, Wright Patterson Air Force Base; Ohio 45433
| | - Huai Yang
- Department of Materials Science and Engineering; College of Engineering, and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University; Beijing 100871 People's Republic of China
| | - Timothy Bunning
- Air Force Research Laboratory; Materials and Manufacturing Directorate, Wright Patterson Air Force Base; Ohio 45433
| | - Deng-Ke Yang
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University; Kent Ohio 44242
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Madhuri PL, Hiremath US, Yelamaggad CV, Madhuri KP, Prasad SK. Influence of virtual surfaces on Frank elastic constants in a polymer-stabilized bent-core nematic liquid crystal. Phys Rev E 2016; 93:042706. [PMID: 27176365 DOI: 10.1103/physreve.93.042706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Indexed: 06/05/2023]
Abstract
Effect of a polymer network on the threshold voltage of the Fréedericksz transition, Frank elastic constants, switching speed, and the rotational viscosity are investigated in a polymer-stabilized bent-core nematic liquid crystal with different polymer concentrations. These polymer networks form virtual surfaces with a finite anchoring energy. The studies bring out several differences in comparison to similar studies with a calamitic liquid crystal as the nematic host. For example, on varying the polymer content the threshold voltage decreases initially, but exhibits a drastic increase above a critical concentration. A similar feature-reaching a minimum before rising-is seen for the bend elastic constant, which gets enhanced by an order of magnitude for a polymer content of 2.5 wt %. In contrast, the splay elastic constant has a monotonic variation although the overall enhancement is comparable to that of the bend elastic constant. The behavior changing at a critical concentration is also seen for the switching time and the associated rotational viscosity. The presence of the polymer also induces a shape change in the thermal dependence of the bend elastic constant. We explain the features observed here on the basis of images obtained from the optical and atomic force microscopy.
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Affiliation(s)
- P Lakshmi Madhuri
- Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013, India
| | - Uma S Hiremath
- Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013, India
| | - C V Yelamaggad
- Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013, India
| | - K Priya Madhuri
- Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013, India
| | - S Krishna Prasad
- Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013, India
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14
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Lee KM, Tondiglia VP, White TJ. Photosensitivity of reflection notch tuning and broadening in polymer stabilized cholesteric liquid crystals. SOFT MATTER 2016; 12:1256-1261. [PMID: 26593860 DOI: 10.1039/c5sm01985k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The position or bandwidth of the selective reflection of polymer stabilized cholesteric liquid crystals (PSCLCs) prepared from negative dielectric anisotropy ("-Δε") liquid crystalline hosts can be shifted by applying a DC voltage. The underlying mechanism of the tuning or broadening of the reflection of PSCLCs detailed in these recent efforts is ion-facilitated, electromechanical deformation of the structurally chiral, polymer stabilizing network in the presence of a DC bias. Here, we show that these electro-optic responses can also be photosensitive. The photosensitivity is most directly related to the presence of photoinitiator, which is a known ionic contaminant to liquid crystal devices. Measurement of the ion density of a series of control compositions before, during, and after irradiation with UV light confirms that the ion density in compositions that exhibit photosensitivity is increased by irradiation and correlates to not only the concentration of the photoinitiator but also the type. Thus, the magnitude of the electrically tuned or broadened reflection of PSCLC of certain compositions when subjected to DC field is further increased in the presence of UV light. While interesting and potentially useful in applications such as architectural windows, the effect may be deleterious to some device implementations. Accordingly, compositions in which photosensitivity is not observed are identified.
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Affiliation(s)
- Kyung Min Lee
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433-7750, USA.
| | - Vincent P Tondiglia
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433-7750, USA.
| | - Timothy J White
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433-7750, USA.
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15
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Nemati H, Liu S, Zola RS, Tondiglia VP, Lee KM, White T, Bunning T, Yang DK. Mechanism of electrically induced photonic band gap broadening in polymer stabilized cholesteric liquid crystals with negative dielectric anisotropies. SOFT MATTER 2015; 11:1208-1213. [PMID: 25567417 DOI: 10.1039/c4sm02283a] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We experimentally observed that the photonic band gap (reflection band) of polymer stabilized cholesteric liquid crystals with negative dielectric anisotropies can be greatly broadened under DC electric fields. We explored the underlying mechanism. We found that the dispersed polymer network moved when DC voltages were applied across the liquid crystal cell. The motion of the polymer network stretched the helical pitch of the liquid crystal on one side of the cell and compressed the helical pitch on the other side of the cell. We proposed a phenomenological theory to explain the motion of the polymer network and the effect of the polymer network on the helical pitch, and this theoretical prediction agreed well with the experimental results.
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Affiliation(s)
- Hossein Nemati
- Chemical Physics Interdisciplinary Program, Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA.
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16
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Li CC, Tseng HY, Pai TW, Wu YC, Hsu WH, Jau HC, Chen CW, Lin TH. Bistable cholesteric liquid crystal light shutter with multielectrode driving. APPLIED OPTICS 2014; 53:E33-E37. [PMID: 25090351 DOI: 10.1364/ao.53.000e33] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 05/05/2014] [Indexed: 06/03/2023]
Abstract
An electrically activated bistable light shutter that exploits polymer-stabilized cholesteric liquid crystal film was developed. Under double-sided three-terminal electrode driving, the device can be bistable and switched between focal conic and homeotropic textures with a uniform in-plane and vertical electrical field. The transparent state with a transmittance of 80% and the opaque/scattering state with a transmittance of 13% can be realized without any optical compensation film, and each can be simply switched to the other by applying a pulse voltage. Also, gray-scale selection can be performed by varying the applied voltage. The designed energy-saving bistable light shutter can be utilized to preserve privacy and control illumination and the flow of energy.
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17
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Sonin AS, Churochkina NA. Liquid crystals stabilized by physical networks. POLYMER SCIENCE SERIES A 2013. [DOI: 10.1134/s0965545x13060060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Babilotte P, Silva VNH, Dubreuil M, Rivet S, Dupont L, Le Jeune B. Impact of the concentration in polymer on the dynamic behavior of Polymer Stabilized Ferroelectric Liquid Crystal using Snap-shot Mueller Matrix Polarimetry. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2013; 36:55. [PMID: 23715883 DOI: 10.1140/epje/i2013-13055-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 02/17/2013] [Accepted: 04/25/2013] [Indexed: 06/02/2023]
Abstract
Experimental results are presented related to the dynamic behaviour of Polymer Stabilized Ferro-electric Liquid Crystal (PSFLC) samples under external applied electric field, using Snap-shot Mueller Matrix Polarimetry (SMMP) and Mueller Matrix (MM) formalism. Different polarimetric coefficients are simultaneously extracted from each channeled spectrum measured with this full-optical SMMP technique. The impact of the concentration of polymer present into the liquid crystal cell on this dynamic behaviour is studied, permitting a direct and quick characterisation of the material. The results obtained for PSFLC are compared with those already measured for pure Surface Stabilized Ferro-electric Liquid Crystal (SSFLC) samples, which correspond to a 0% concentration in polymer.
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Affiliation(s)
- Philippe Babilotte
- Université Europeenne de Bretagne, 5 Boulevard Laennec, 35000, Rennes, France.
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Guo R, Li K, Cao H, Wu X, Wang G, Cheng Z, Wang F, Zhang H, Yang H. Chiral polymer networks with a broad reflection band achieved with varying temperature. POLYMER 2010. [DOI: 10.1016/j.polymer.2010.10.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kinkead B, Hegmann T. Effects of size, capping agent, and concentration of CdSe and CdTequantum dots doped into a nematic liquid crystal on the optical and electro-optic properties of the final colloidal liquid crystal mixture. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b911641a] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Guo J, Wu H, Chen F, Zhang L, He W, Yang H, Wei J. Fabrication of multi-pitched photonic structure in cholesteric liquid crystals based on a polymer template with helical structure. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b926670d] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Huang CY, Ma JM, Mo TS, Lo KC, Lo KY, Lee CR. All-optical and polarization-independent spatial filter based on a vertically-aligned polymer-stabilized liquid crystal film with a photoconductive layer. OPTICS EXPRESS 2009; 17:22386-22392. [PMID: 20052162 DOI: 10.1364/oe.17.022386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
An all-optical and polarization-independent spatial filter was developed in a vertically-aligned (VA) polymer-stabilized liquid crystal (PSLC) film with a photoconductive (PC) layer. This spatial filter is based on the effect of light on the conductivity of PC layer: high (low)-intensity light makes the conductivity of the PC layer high (low), resulting in a low (high) threshold voltage of the PC-coated VA PSLC cell. Experimental results indicate that this spatial filter is a high-pass filter with low optical-power consumption (about 1.11 mW/cm(2)) in an optical Fourier transform system. The high-pass characteristic was confirmed by simulation. Accordingly, the all-optical and polarization-independent spatial filter can be used to enhance the edges of images.
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Affiliation(s)
- Chia-Yi Huang
- Institute of Electro-Optical Science and Engineering and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan 701, Republic of China
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Guo J, Liu F, Zhang L, Cao H, Yang H. Preparation and reflectance properties of new cholesteric liquid crystalline copolymers containing cholesteryl group. POLYM ENG SCI 2009. [DOI: 10.1002/pen.21223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Petit M, Hemine J, Daoudi A, Ismaili M, Buisine JM, Da Costa A. Effect of the network density on dynamics of the soft and the Goldstone modes in short-pitch ferroelectric liquid crystals stabilized by an anisotropic polymer network. Phys Rev E 2009; 79:031705. [PMID: 19391960 DOI: 10.1103/physreve.79.031705] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Revised: 06/27/2008] [Indexed: 11/07/2022]
Abstract
We report the influence of the polymer network density formed in short-pitch ferroelectric liquid crystal (FLC) on the soft and the Goldstone dielectric relaxation modes. The experimental results of the pure FLC and the FLC stabilized by a polymer network with various densities are presented and compared. These results reveal that in the SmC;{ *} phase, when the polymer concentration increases, the Goldstone dielectric strength gradually decreases and the relaxation frequency is shifted to higher values. In the SmA;{ *} phase, the results show that close to the SmC;{ *}-SmA;{ *} transition temperature, T_{c} , the soft relaxation mode is largely influenced by the polymer network: a sharp decrease in the dielectric strength and an increase in the relaxation frequency when the polymer density increases were observed. The soft mode is relatively weakly affected by the network for higher temperatures (T> or =T_{c}+0.5 degrees C) . This indicates that the behavior of the soft mode for this temperature domain is dominated rather by thermal effects than by the network. A simple phenomenological approach was proposed to explain the behavior of the soft-mode dielectric strength versus polymer concentration. This model takes into account the anisotropic interaction between the polymer network and the liquid crystal, and the elastic interaction resulting from the anchoring of the liquid crystal molecules at the polymer surfaces. The experimental results are in agreement with the proposed model.
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Affiliation(s)
- Mohamed Petit
- Laboratoire de Thermophysique de la Matière Condensée-Equipe de l' UMR-CNRS 8024, Université du Littoral Côte d'Opale, 145, Avenue Maurice Schumann, 59140 Dunkerque, France
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He J, Yan B, Yu B, Wang S, Wang X, Wang J, Zeng Y, Ran R, Wang Y. Fine adjustment of network in polymer network liquid crystal film employing RAFT polymerization. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/pola.22623] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Guo J, Sun J, Zhang L, Li K, Cao H, Yang H, Zhu S. Broadband reflection in polymer stabilized cholesteric liquid crystal cells with chiral monomers derived from cholesterol. POLYM ADVAN TECHNOL 2008. [DOI: 10.1002/pat.1155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Petit M, Daoudi A, Ismaili M, Buisine JM. Electroclinic effect in a chiral smectic-A liquid crystal stabilized by an anisotropic polymer network. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:061707. [PMID: 17280084 DOI: 10.1103/physreve.74.061707] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Indexed: 05/13/2023]
Abstract
We have studied the effect of an anisotropic polymer network on the coupling of molecular tilt to applied electric field in the chiral S{A} phase. The polymer network is formed from a photoreactive achiral monomer in a thin planar S{C}{*} cell. Experimental data, obtained from electro-optical measurements near to the S{A}-S{c}{*} transition temperature, T{c} , of the induced molecular tilt, switching time, as well as induced polarization as a function of temperature and electric field strength are presented. The results clearly show that, close to T{c} , the electroclinic effect is largely controlled by the polymer network. The experimental results are discussed in the framework of a simple phenomenological model, extended from the Landau model, which includes the bulk free energy arising from the anisotropic interaction between the polymer network and the liquid crystal director, and the elastic free energy resulting from the anchoring (supposed rigid) of the liquid crystal molecules at the polymer boundaries.
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Affiliation(s)
- Mohamed Petit
- Laboratoire de Thermophysique de la Matière Condensée, Equipe de l' UMR-CNRS 8024 Université du Littoral Côte d'Opale, 145 Avenue Maurice Schumann 59140 Dunkerque, France
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Petit M, Daoudi A, Ismaili M, Buisine JM. Distortion and unwinding of the helical structure in polymer-stabilized short-pitch ferroelectric liquid crystal. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 20:327-33. [PMID: 16865324 DOI: 10.1140/epje/i2006-10022-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Accepted: 07/07/2006] [Indexed: 05/11/2023]
Abstract
We report the effect of an anisotropic polymer network formed from an achiral photoreactive monomer in a short-pitch chiral SmC* phase on the distortion and the unwinding of the helical structure of the ferroelectric phase. The electro-optical behaviour and ferroelectric properties were experimentally determined for films containing various polymer concentrations. The critical field, E(u), for the transition from the distorted structure to the homogeneous state was measured as a function of polymer concentration. A linear increase of E(u) versus polymer concentration was observed, showing that the helical structure of the short-pitch SmC* phase was stabilized by the polymer network. This behaviour was expected to be a consequence of the increase of the apparent elastic constants of the ferroelectric liquid crystal stabilized by the anisotropic polymer network films. The polymer network morphology was investigated using atomic-force microscopy, revealing a twisted structure of the polymer fibers. This twisted structure was transferred onto a polymer network during the polymerization process within a short-pitch SmC* phase. The increase of the apparent elasticity can then be interpreted by a strong interaction between polymer network and the liquid-crystal molecules. From our experimental data, the coupling coefficient, W(p), characterizing this interaction was evaluated for all studied polymer concentrations.
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Affiliation(s)
- M Petit
- Laboratoire de Thermophysique de la Matière Condensée, Equipe de l'UMR-CNRS 8024, Université du Littoral Côte d'Opale, 145, Avenue Maurice Schumann, 59140, Dunkerque, France
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Darinskii AA, Zarembo A, Balabaev NK, Neelov IM, Sundholm F. Molecular dynamics simulation of a flexible polymer network in a liquid crystal solvent; structure and equilibrium properties. POLYMER 2004. [DOI: 10.1016/j.polymer.2004.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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