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14 pages, 5150 KiB

Open AccessArticle

Reflectivity and Angular Anisotropy of Liquid Crystal Microcapsules with Different Particle Sizes by Complex Coalescence

by Yonggang Yang, Yuchen Cui, Yinjie Chen, Yanan Guo, **aoqi Liu, **a Chen, Jianghao Liu, Yu Liu and Zhengfeng Liu

Molecules 2024, 29(13), 3030; https://doi.org/10.3390/molecules29133030 - 26 Jun 2024

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Abstract

Cholesteric liquid crystal microcapsules (CLCMs) are used to improve the stability of liquid crystals while ensuring their stimulus response performance and versatility, with representative applications such as sensing, anticounterfeiting, and smart fabrics. However, the reflectivity and angular anisotropy decrease because of the anchoring effect of the polymer shell matrix, and the influence of particle size on this has not been thoroughly studied. In this study, the effect of synthesis technology on microcapsule particle size was investigated using a complex coalescence method, and the effect of particle size on the reflectivity and angular anisotropy of CLCMs was investigated in detail. A particle size of approximately 66 µm with polyvinyl alcohol (PVA, 1:1) exhibited a relative reflectivity of 16.6% and a bandwidth of 20 nm, as well as a narrow particle size distribution of 22 µm. The thermosetting of microcapsules coated with PVA was adjusted and systematically investigated by controlling the mass ratio. The optimized mass ratio of microcapsules (66 µm) to PVA was 2:1, increasing the relative reflectivity from 16.6% (1:1) to 32.0% (2:1) because of both the higher CLCM content and the matching between the birefringence of the gelatin–arabic shell system and PVA. Furthermore, color based on Bragg reflections was observed in the CLCM-coated ortho-axis and blue-shifted off-axis, and this change was correlated with the CLCM particle size. Such materials are promising for anticounterfeiting and color-based applications with bright colors and angular anisotropy in reflection. Full article

(This article belongs to the Special Issue Structural Design and Preparation of Liquid Crystal/Polymer Composite Films)

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16 pages, 17743 KiB

Open AccessArticle

Preparation of Progressive Driving Bilayer Polymer-Dispersed Liquid Crystals Possessing a PDLC-PVA-PDLC Structure

by Yongle Wu, Yuzhen Zhao and Dong Wang

Molecules 2024, 29(2), 508; https://doi.org/10.3390/molecules29020508 - 19 Jan 2024

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Abstract

In this paper, the bilayer polymer-dispersed liquid crystals possessing a PDLC-PVA-PDLC structure were prepared by integrating two monolayer PDLCs. The effect of the polymer mesh size on the electro–optical properties of a bilayer PDLC was investigated by comparing the micro-morphology and electro–optical curves under different polymerization conditions. In addition, the impact of do** MoO₂ nanoparticles with surface modification on the comprehensive performance of the bilayer PDLC was further researched. The contrast ratio of the bilayer PDLC prepared under the optimal conditions was improved by more than 90% and still maintained excellent progressive driving performance. Therefore, the development of a bilayer PDLC with optimal electro-optical properties will significantly enhance the technological prospects for the application of PDLC-based devices in smart windows, displays, and flexible devices. Full article

(This article belongs to the Special Issue Structural Design and Preparation of Liquid Crystal/Polymer Composite Films)

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11 pages, 3428 KiB

Open AccessArticle

High-Throughput Preparation and High-Throughput Detection of Polymer-Dispersed Liquid Crystals Based on Ink-Jet Printing and Grayscale Value Analysis

by Rui-Juan **ong, Yun-**ao Ren, Yong-Feng Cui, Shu-Feng Cai, Wan-Li He and **ao-Tao Yuan

Molecules 2023, 28(5), 2253; https://doi.org/10.3390/molecules28052253 - 28 Feb 2023

Viewed by 1096

Abstract

In this paper, based on high-throughput technology, polymer dispersed liquid crystals (PDLC) composed of pentaerythritol tetra (2-mercaptoacetic acid) (PETMP), trimethylolpropane triacrylate (TMPTA), and polyethylene glycol diacrylate (PEGD 600) were investigated in detail. A total of 125 PDLC samples with different ratios were quickly prepared using ink-jet printing. Based on the method of machine vision to identify the grayscale level of samples, as far as we know, it is the first time to realize high-throughput detection of the electro-optical performance of PDLC samples, which can quickly screen out the lowest saturation voltage of batch samples. Additionally, we compared the electro-optical test results of manual and high-throughput preparation PDLC samples and discovered that they had very similar electro-optical characteristics and morphologies. This demonstrated the viability of PDLC sample high-throughput preparation and detection, as well as promising application prospects, and significantly increased the efficiency of PDLC sample preparation and detection. The results of this study will contribute to the research and application of PDLC composites in the future. Full article

(This article belongs to the Special Issue Structural Design and Preparation of Liquid Crystal/Polymer Composite Films)

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