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Yu M, He X, Qin J, Hu Y, Wang Q, Zou C, Wei H, Wang X, Gao Y, Yang H. Impact of crosslinking agents with steric cyclic groups on the properties of polymer-dispersed liquid crystals. Phys Chem Chem Phys 2024; 26:7388-7397. [PMID: 38351835 DOI: 10.1039/d3cp05683j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
As a type of intelligent dimming film, polymer-dispersed liquid crystals (PDLCs) have been widely applied in various fields, such as smart windows, light shutters and displays. The properties of PDLCs are greatly influenced by the structure of the raw materials. In this work, the impact of crosslinking agents with different cyclic or chain groups was investigated by comparing the electro-optical performance and the morphology of the polymer matrix in the as-made PDLC films. It was found that the incorporation of large steric groups into the crosslinking agents can alter the morphology of the polymer matrix and thus affect the electro-optical properties. However, the impact is distinct when the spatial structure or rigidity is different. Besides, a combination of crosslinking agents with flexible alkyl-chain structures and steric structures can further reduce the threshold voltage while keeping the high contrast ratio. After detailed comparison, an optimized combination of BDDA/TCDDA in a weight ratio of 1/1 is selected to demonstrate the enhanced properties of the as-constructed film with a thickness of 20 μm. It exhibits low threshold voltage (8.2 V), low saturation voltage (21.2 V) and a high contrast ratio (203) simultaneously. This research offers an optimizing method from the crosslinking agent perspective and is anticipated to promote the further improvement of the PDLC's performance.
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Affiliation(s)
- Meina Yu
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Xian He
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Jing Qin
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Yongchuan Hu
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Qian Wang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Cheng Zou
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing, China
| | - Huiyun Wei
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China
| | - Xiao Wang
- School of Materials Science and Engineering, Peking University, Beijing 100871, China.
| | - Yanzi Gao
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Huai Yang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing, China
- School of Materials Science and Engineering, Peking University, Beijing 100871, China.
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A Stable PDLC Film with High Ageing Resistance from an Optimized System Containing Rigid Monomer. Molecules 2023; 28:molecules28041887. [PMID: 36838878 PMCID: PMC9962081 DOI: 10.3390/molecules28041887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/19/2023] Open
Abstract
With the switchability between transparent and light-scattering states, polymer-dispersed liquid crystals (PDLC) are widely used as smart windows, flexible display devices, projectors, and other devices. In outdoor applications, in addition to excellent electro-optical properties, there is also a high demand for film stability. In this work, a PDLC film with high mechanical strength and structural stability is prepared that can maintain stability at 80 °C for 2000 h. By choosing liquid crystals with a wide temperature range, adopting acrylate polymer monomers containing hydroxyl groups, and adjusting the polymer content, the PDLC film can work well from -20 °C to 80 °C. On this basis, the effects of the introduction of rigid monomers on the mechanical properties and electro-optical properties of PDLC films are investigated.
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Zhong T, Mandle RJ, Goodby JW, Zhang L, Zhang C. Comparative studies of polymer‐dispersed liquid crystal films via a thiol‐ene click reaction. POLYM ADVAN TECHNOL 2019. [DOI: 10.1002/pat.4710] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tingjun Zhong
- Department of Materials Science and Engineering, College of EngineeringPeking University Beijing China
| | | | | | - Lanying Zhang
- Department of Materials Science and Engineering, College of EngineeringPeking University Beijing China
| | - Cuihong Zhang
- Key Laboratory of Organic Polymer Photoelectric Materials, School of ScienceXijing University Xi'an China
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Kumar S, Hong H, Choi W, Akhtar I, Rehman MA, Seo Y. Acrylate-assisted fractal nanostructured polymer dispersed liquid crystal droplet based vibrant colored smart-windows. RSC Adv 2019; 9:12645-12655. [PMID: 35515860 PMCID: PMC9063710 DOI: 10.1039/c9ra00729f] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 04/17/2019] [Indexed: 11/21/2022] Open
Abstract
We have studied liquid crystals (LCs) and acrylate-assisted thiol–ene compositions to synthesize dye based colorful polymer dispersed liquid crystals (PDLCs) without using a photo-initiator for smart-windows applications. A typical PDLC mixture was prepared by mixing LCs with UV-curable monomers, which included triethylene glycol diacrylate (TEGDA), trimethylolpropane diallyl ether (TMPDE, di-functional ene monomer), trimethylolpropane tris(3-mercaptopropionate) (TMPTMP, a thiol as a cross-linker), and a dichroic dye. The ratios of the TMPDE/TMPTMP and the LCs/TEGDA showed significant effects in altering the properties of the UV-cured PDLCs. During the curing process, the monomers polymerize and led to the encapsulation of the LCs in the form of interesting fractal nanostructures by a polymerization induced phase separation process. The switching time, electro-optical properties, power consumption, and ageing of the fabricated PDLCs were investigated. It was possible to achieve a 70–80% contrast (ΔT) at a voltage difference of ∼70 V with a fast switching time (τ) as low as < 20 milliseconds (ms) and low power consumption. These PDLCs had a low threshold voltage that ranged between 10 and 20 V. The sustainability of the fabricated UV-cured PDLCs was analyzed for up to 90 days, and the PDLCs were observed to be stable. Vibrant colored smart-windows were fabricated based on acrylate-assisted fractal nanostructured polymer dispersed liquid crystals.![]()
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Affiliation(s)
- Sunil Kumar
- Graphene Research Institute and HMC
- Sejong University
- Seoul
- South Korea
- Department of Nanotechnology and Advanced Materials Engineering
| | - Hyeryeon Hong
- Department of Nanotechnology and Advanced Materials Engineering
- Sejong University
- Seoul
- South Korea
| | - Woosuk Choi
- Department of Nanotechnology and Advanced Materials Engineering
- Sejong University
- Seoul
- South Korea
| | - Imtisal Akhtar
- Department of Nanotechnology and Advanced Materials Engineering
- Sejong University
- Seoul
- South Korea
| | - Malik Abdul Rehman
- Department of Nanotechnology and Advanced Materials Engineering
- Sejong University
- Seoul
- South Korea
| | - Yongho Seo
- Graphene Research Institute and HMC
- Sejong University
- Seoul
- South Korea
- Department of Nanotechnology and Advanced Materials Engineering
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Hu W, Chen M, Zhou L, Zhong T, Yuan X, Chen F, Zhang L. Nonelectric Sustaining Bistable Polymer Framework Liquid Crystal Films with a Novel Semirigid Polymer Matrix. ACS APPLIED MATERIALS & INTERFACES 2018; 10:22757-22766. [PMID: 29894150 DOI: 10.1021/acsami.8b06324] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this work, a bistable polymer framework liquid crystal (PFLC) thin film by thermal curing of epoxy monomers with two different thiols, a traditional flexible-structure thiol and a novel original rigid-structure thiol, has been successfully fabricated, combining a novel mixed morphology of polymer matrix and cholesteric liquid crystals with negative dielectric anisotropy. The polymer framework morphology has been formed by curing two types of epoxy monomers with two types of thiols, and the liquid crystals tend to be focal conic textures with large size domains at the initial state in the PFLC film so that it has a moderate light transmissivity at this state between the transparent state and the opaque state. Thus, the devices based on PFLC films can be switched reversibly between the transparent state and the opaque state by alternative electric field. In addition, the states can be sustained after the electric field is removed. The bistable memory effect comes from the anchoring effects of the polymer frameworks with a novel morphology in the microdomains of the PFLCs. Therefore, the optimized bistable PFLC film keeps its initial state without external electric field and any other energy consumption for a long time after altering the state by applying an instant electric field. The special polymer frameworks in the bistable PFLC films endow the films with excellent electro-optical properties and mechanical properties. The devices are energy-efficient and cost-saving and have great potential applications in energy-efficient reflective displays, electronic papers, writing tablets, and smart windows.
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Affiliation(s)
- Wei Hu
- Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China
| | - Mei Chen
- Department of Materials Science and Engineering, College of Engineering , Peking University , Beijing 100871 , People's Republic of China
| | - Le Zhou
- Department of Materials Science and Engineering, College of Engineering , Peking University , Beijing 100871 , People's Republic of China
| | - Tingjun Zhong
- Department of Materials Science and Engineering, College of Engineering , Peking University , Beijing 100871 , People's Republic of China
| | - Xiaotao Yuan
- Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China
| | - Feiwu Chen
- Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering , University of Science and Technology Beijing , Beijing 100083 , People's Republic of China
| | - Lanying Zhang
- Department of Materials Science and Engineering, College of Engineering , Peking University , Beijing 100871 , People's Republic of China
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