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Shi Y, Song Z, Wu Y, Gao Y, Yu M, Yang H, Zou C. A Multi-Functional Molecule for Highly Durable, Bending-Resistant, Low-Voltage Driving PSLC Films toward Smart Windows With Radiative Cooling. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2407707. [PMID: 39632374 DOI: 10.1002/smll.202407707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2024] [Revised: 11/14/2024] [Indexed: 12/07/2024]
Abstract
Polymer-stabilized liquid crystals (PSLCs) are widely used in smart windows, light modulators, and dimmed glass. However, their low mechanical strength, unsatisfactory electro-optical properties, and poor durability limit their large-scale application. In this study, a PSLC film with outstanding performance is prepared by incorporating a multifunctional molecule into a fine-sculptured liquid crystal/polymer composite. The multifunctional molecule is designed to form a vertically oriented layer with a silane coupling agent through a two-step self-assembly process and improve the mechanical strength of PSLCs by connecting the polymer networks through covalent bonds. In addition, it endowed the film with good thermal stability through the reversible change from hydrogen bonds at low temperatures to C═N bonds at high temperatures. A PSLC film with ultralow saturation voltage (Vsat < 25 V), wide operating temperature and viewing angle performance, high mechanical strength (60-100% improvement), and high stability (15 000 cycles) is prepared through the self-assembly of the multifunctional molecule followed by photomask-assisted photopolymerization. Finally, a bending-resistant, flexible PSLC film with passive radiative cooling capacity is tested and achieved excellent temperature management. This composite film demonstrated superior performance in every aspect, promoting the application of PSLCs in smart windows for cars and buildings.
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Affiliation(s)
- Yingjie Shi
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China
| | - Zhexu Song
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yishuo Wu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China
| | - Yanzi Gao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China
| | - Meina Yu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China
| | - Huai Yang
- School of Materials Science and Engineering, Peking University, Beijing, 100083, China
| | - Cheng Zou
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China
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Yu P, He Z, Zhao Y, Song W, Miao Z. Reverse Mode Polymer Stabilized Cholesteric Liquid Crystal Flexible Films with Excellent Bending Resistance. Molecules 2024; 29:4276. [PMID: 39275123 PMCID: PMC11397460 DOI: 10.3390/molecules29174276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2024] [Revised: 09/05/2024] [Accepted: 09/06/2024] [Indexed: 09/16/2024] Open
Abstract
The reverse-mode smart windows, which usually fabricated by polymer stabilized liquid crystal (PSLC), are more practical for scenarios where high transparency is a priority for most of the time. However, the polymer stabilized cholesteric liquid crystal (PSCLC) film exhibits poor spacing stability due to the mobility of CLC molecules during the bending deformation. In this work, a reverse-mode PSCLC flexible film with excellent bending resistance was fabricated by the construction of polymer spacer columns. The effect of the concentration of the polymerizable monomer C6M and chiral dopant R811 on the electro-optical properties and polymer microstructure of the film were studied. The sample B2 containing 3 wt% of C6M and 3 wt% R811 presented the best electro-optical performance. The electrical switch between transparent and opaque state of the flexible PSCLC film after bending not only indicated the excellent electro-optical switching performance, but also demonstrated the outstanding bending resistance of the sample with polymer spacer columns, which makes the PSCLC film containing polymer spacer columns have a great potential to be applied in the field of flexible devices.
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Affiliation(s)
- Ping Yu
- Technological Institute of Materials & Energy Science (TIMES), Xi'an Key Laboratory of Advanced Photo-Electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Zemin He
- Technological Institute of Materials & Energy Science (TIMES), Xi'an Key Laboratory of Advanced Photo-Electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Yuzhen Zhao
- Technological Institute of Materials & Energy Science (TIMES), Xi'an Key Laboratory of Advanced Photo-Electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Wenqi Song
- Technological Institute of Materials & Energy Science (TIMES), Xi'an Key Laboratory of Advanced Photo-Electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Zongcheng Miao
- School of Artificial Intelligence, Optics and Electronics (IOPEN), Northwestern Polytechnical University, Xi'an 710072, China
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Wu Y, Shang G, Ma C, Shi Y, Song Z, Wang P, Gao Y, Wang Q, Yu M, Xiao J, Zou C. Study on the Polymer Morphology and Electro-Optical Performance of Acrylate/Epoxy Resin-Based Polymer-Stabilized Liquid Crystals Based on Stepwise Photopolymerization. Polymers (Basel) 2024; 16:2446. [PMID: 39274079 PMCID: PMC11398129 DOI: 10.3390/polym16172446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2024] [Revised: 08/25/2024] [Accepted: 08/27/2024] [Indexed: 09/16/2024] Open
Abstract
Stepwise photopolymerization is a miraculous strategy modulating the polymer skeleton and electro-optical properties of light modulators based on liquid crystal/polymer composites. However, owing to the indistinct polymerization mechanism and curing condition discrepancy, the required polymer structures and electro-optical properties are hard to be controlled precisely. Herein, a novel polymer-stabilized liquid crystal film based on acrylate/epoxy resin is proposed, fabricated and the relationships between preparation process, polymer content, polymer morphology and electro-optical properties are studied. The in-situ photopolymerization of acrylate/epoxy resin liquid crystalline polymer is fulfilled using cation photo-initiator UV 6976. The distinct photopolymerization speed between acrylate and epoxy resin benefits the polymer morphology control, and with accurate containment of the polymerization process and polymer composition, the superior electro-optical properties at a higher polymer content are acquired. The polymer morphology and electro-optical properties are influenced by the polymer content and mass ratio between acrylate and epoxy resin. The best electro-optical properties among samples are attained by controlling the mass ratio between acrylate and epoxy resin to 1:1, integrating higher densities of scattering centers and lower anchoring effect. With higher polymer content, the strategy of increasing the mass ratio of E6M benefits the improvement of E-O properties for alleviating polymer density. This work provides insights to stepwise polymerization of liquid crystalline monomers and offers a fancy strategy for the preparation of novel liquid crystal dimming films.
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Affiliation(s)
- Yishuo Wu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Guangyang Shang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Cong Ma
- Strategic Business Unit of Chlor-Alkali, Sinochem Group, Beijing 100031, China
| | - Yingjie Shi
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Zhexu Song
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Peixiang Wang
- Yantai Xianhua Technology Group Co., Ltd., Yantai 264006, China
| | - Yanzi Gao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Qian Wang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Meina Yu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Jiumei Xiao
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China
| | - Cheng Zou
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
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Wu Y, Zou C, Shi Y, Song Z, Xiao J, Yu M, Gao Y, Wang Q, Yang H. Reverse-Mode Polymer-Stabilized Liquid Crystal Films with Enhanced Peel Strength and Electro-Optical Performance Based on Photoreactive Self-Assembly Alignment Layers and Patterned Polymer Walls. ACS APPLIED MATERIALS & INTERFACES 2024; 16:40046-40055. [PMID: 39025782 DOI: 10.1021/acsami.4c08934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Polymer-stabilized liquid crystal (PSLC) is a promising material toward the practical application of serving as energy-saving reverse-mode smart windows owing to its superior electro-optical (E-O) properties, simple and efficient processability, and compatibility to most practical circumstances. However, its feeble peel strength originated from low polymer content and poor adhesion between polymer networks and substrates inhibited its large-scale flexible film production. It is still a challenging task to derive good mechanical properties and superior E-O performance for PSLCs at the same time. In this study, a highly durable liquid crystal/polymer composite film showing enhanced peel strength and excellent E-O properties was attained by simultaneously building photoreactive self-assemble alignment layers through an efficient one-step method and the sculpture of a patterned polymer wall structure. This film has comprehensive ascendant E-O properties of lower driving voltages, faster response times, and higher contrast ratio, together with an over 30 times lift of the peel strength. The effectuation mechanisms of the alignment, E-O properties, peel-strength, microstructures, and cyclic durability of the films have been systematically studied. This novel liquid crystal/polymer composite film demonstrates advantages in every aspect of performance compared to traditional PSLC devices, which hoards promising applications in smart windows for cars and buildings.
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Affiliation(s)
- Yishuo Wu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Cheng Zou
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Yingjie Shi
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Zhexu Song
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Jiumei Xiao
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China
| | - Meina Yu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Yanzi Gao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Qian Wang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
| | - Huai Yang
- School of Materials Science and Engineering, Peking University, Beijing 100083, China
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Zhang X, Lin W, Liu J, Liu J, Weng C. Tuning Electro-Optical Characteristics through Polymerization Monomer Content in PSVA Liquid Crystal Displays: Simulation and Experimentation. Polymers (Basel) 2024; 16:1606. [PMID: 38891552 PMCID: PMC11174515 DOI: 10.3390/polym16111606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 06/03/2024] [Accepted: 06/03/2024] [Indexed: 06/21/2024] Open
Abstract
The enhancement of display performance and durability in polymer-stabilized vertical alignment liquid crystal and the liquid crystal are negative liquid crystals, which can be vertically aligned under the action of a vertical orientation layer and an electric field. Devices (PSVA LCDs) are crucial for advancing LCD technology. This study aims to investigate the electro-optical characteristics of PSVA LCDs by varying polymerization monomer concentrations. Using both simulations via TechWiz LCD 3D and experimental methods, such as polymer-induced phase separation, we developed an optoelectronic testing framework to assess voltage transmittance and response times. In our main findings, we show that an increase in polymeric monomer concentration from 3% to 7% resulted in a 67% increase in threshold voltage and a 44% decrease in saturation voltage. The on-state response time increased by about a factor of three, while the off-state response time decreased by about a factor of three. The alignment of our simulation results with experimental data validates our methodology, offering the potential of simulation tools as a pivotal resource in the PSVA LCDs. The alignment of our simulation results with experimental data validates our methodology, offering the potential of simulation tools as a pivotal resource in the PSVA LCDs. These advancements promise significant improvements in PSVA LCD performance and durability.
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Affiliation(s)
- Xiaoyu Zhang
- College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
| | - Wei Lin
- College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
| | - Jiezhen Liu
- College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
| | - Jiangwen Liu
- Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Can Weng
- College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
- State Key Laboratory of Precision Manufacturing for Extreme Service Performance, Central South University, Changsha 410083, China
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Zhang Y, Yang H, Chen Y, Yu H. Progress in Fabrication and Applications of Cholesteric Liquid Crystal Microcapsules. Chemistry 2024; 30:e202303198. [PMID: 37971158 DOI: 10.1002/chem.202303198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 11/15/2023] [Accepted: 11/15/2023] [Indexed: 11/19/2023]
Abstract
Liquid crystals (LCs) are well known for inherent responsiveness to external stimuli, such as light, thermal, magnetic, and electric fields. Cholesteric LCs are among the most fascinating, since they possess distinctive optical properties due to the helical molecular orientation. However, the good flow, easy contamination, and poor stability of small-molecule LCs limit their further applications, and microencapsulation as one of the most effective tools can evade these disadvantages. Microencapsulation can offer shell-core structure with LCs in the core can strengthen their stability, avoiding interference with the environment while maintaining the stimuli-responsiveness and optical properties. Here, we report recent progress in the fabrication and applications of cholesteric LC microcapsules (CLCMCs). We summarize general properties and basic principles, fabrication methods including interfacial polymerization, in-situ polymerization, complex coacervation, solvent evaporation, microfluidic and polymerization of reactive mesogens, and then give a comprehensive overview of their applications in various popular domains, including smart fabrics, smart sensor, smart displays, anti-counterfeiting, information encryption, biomedicine and actuators. Finally, we discuss the currently facing challenges and the potential development directions in this field.
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Affiliation(s)
- Yajun Zhang
- College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, 100020, Beijing, China
| | - Haixiao Yang
- College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, 100020, Beijing, China
| | - Yinjie Chen
- Beijing Engineering Research Center of Printed Electronics, Beijing Institute of Graphic Communication, 102600, Beijing, China
| | - Haifeng Yu
- School of Materials Science and Engineering and, Key Laboratory of Polymer Chemistry and, Physics of Ministry of Education, Peking University, 100871, Beijing, China
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Yu M, Xu J, Zhang L, Wang Q, Zou C, Gao Y, Yang H. Balanced electro-optical properties and off-axis haze performance of a polymer-dispersed liquid crystal film via refractive index matching. Phys Chem Chem Phys 2023; 25:23770-23782. [PMID: 37622171 DOI: 10.1039/d3cp03024e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
As a type of smart dimming film, polymer-dispersed liquid crystals (PDLCs) show great prospects in the fields of indoor partition, electronic curtains, and automobile windows. However, its high off-axis haze greatly impacts the application scope. This obvious shortcoming is mainly caused by the serious mismatch between the effective refractive index of the liquid crystal (neff) and the refractive index of the polymer matrix (np) at large viewing angles. Thereby, factors affecting the viewing angle of a PDLC film are analyzed in this research, including the birefringence of the liquid crystal (Δn), film thickness, and the refractive index of the polymer matrix (np). Balanced electro-optical properties are guaranteed simultaneously. It is found that high on-state transmittance and low off-axis haze can be achieved at large viewing angles in the suggested optimized case where Δn is within the range of 0.1-0.13; the film thickness is between 20 μm and 15 μm; and np approaches no but the difference does not exceed 0.03.
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Affiliation(s)
- Meina Yu
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, China.
| | - Jianjun Xu
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, China
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, China
| | - Luoning Zhang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, China.
| | - Qian Wang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, China.
| | - Cheng Zou
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, China.
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yanzi Gao
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, China.
| | - Huai Yang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, China.
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, China
- School of Materials Science and Engineering, Peking University, Beijing, China
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Ye Y, Guo L, Zhong T. A Review of Developments in Polymer Stabilized Liquid Crystals. Polymers (Basel) 2023; 15:2962. [PMID: 37447607 DOI: 10.3390/polym15132962] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/03/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023] Open
Abstract
Polymer-stabilized liquid crystals (PSLCs) are multi-functional materials consisting of polymer networks in a continuous phase of liquid crystals (LCs), of which polymer networks provide anchoring energy to align the LCs. A number of improvements are detailed, including polymer-stabilized nematic liquid crystals (PSNLCs), polymer-stabilized cholesteric liquid crystals (PSCLCs), polymer-stabilized blue phase liquid crystals (PSBPLCs), polymer-stabilized smectic liquid crystals (PSSLCs), polymer-stabilized ferroelectric liquid crystals (PSFLCs), and polymer-stabilized antiferroelectric liquid crystals (PSAFLCs) in this review. Polymer stabilization has achieved multiple functionalities for LCs; in smart windows, a sufficiently strong electric field allows the LCs to reorient and enables switching from a scattering (transparent) state to a transparent (scattering) state. For broadband reflectors, the reflection bandwidth of LCs is manually tuned by electric fields, light, magnetic fields, or temperature. PSBPLCs open a new way for next-generation displays, spatial light modulators, sensors, lasers, lenses, and photonics applications. Polymer networks in PSFLCs or PSAFLCs enhance their grayscale memories utilized in flexible displays and energy-saving smart cards. At the end, the remaining challenges and research opportunities of PSLCs are discussed.
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Affiliation(s)
- Yong Ye
- Nanjing M&C Electronic New Material Co., Ltd., Nanjing 211300, China
| | - Li Guo
- Shanghai Materials Electronics Co., Ltd., Shanghai 201109, China
| | - Tingjun Zhong
- Department of Chemistry, College of Science, China Agricultural University, Beijing 100193, China
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