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Influence of the multi-functional epoxy monomers structure on the electro-optical properties and morphology of polymer-dispersed liquid crystal films

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Abstract

Polymer dispersed liquid crystal (PDLC) films were prepared by polymerization-induced phase separation method with nematic LC content as low as 40 wt%, and the electro-optical properties were carefully investigated. To accomplish this, the structure of multi-functional curable epoxy monomers with different composition feed ratios and the weight percentages of the two groups were examined in this study. The combined effects of heat-curable monomers’ structure on the conspicuous morphology of polymer network of PDLC films formed small holes and suitably distributed coin-like networks in both groups A and B, respectively. The detailed characteristics and morphology of polymer network of PDLC films were analyzed by employing liquid crystal device parameter tester, UV-Vis-NIR spectrophotometer and scanning electron microscope. Meanwhile, the enhanced curing temperature effects on the alkyl chain length, short flexible chain length, and rigid chain segment containing epoxy monomers structure on the increasing morphology of polymer network as well as electro-optical properties of PDLC films were also studied. It was found that the LC domain size of the polymer network could be regulated by adjusting the structure and composition ratio of curable epoxy monomers, and then the electro-optics of the PDLC films could be optimized, which is beneficial for decreasing the total LC content in PDLC devices.

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Acknowledgments

This work was supported by the National Natural Science Fund for Distinguished Young Scholars (Grant No. 51025313), the National Natural Science Foundation (Grant No. 50973010), the National Natural Science Foundation (Grant No. 51173003), the National Natural Science Foundation (Grant No. 51143001), the Research Fund of the State Key Laboratory for Advanced Metals and Materials, the Open Research Fund of the State Key Laboratory of Bioelectronics (Southeast University) and the Fundamental Research Funds for t he Central Universities (Grant No.FRF-TP-12-032A).

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Authors and Affiliations

  1. Department of Materials Physics and Chemistry, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, People’s Republic of China

    Mujtaba Ellahi, Fang Liu, Ping Song, Yanzi Gao, Hui Cao & Huai Yang

  2. Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, People’s Republic of China

    Huai Yang

  3. Department of Physics, University of Science and Technology Beijing, Beijing, 100083, People’s Republic of China

    M. Y. Rafique

  4. School of Mathematics and Physics, University of Science and Technology Beijing, Beijing, 100083, People’s Republic of China

    Murad Ali Khaskheli

  5. Department of Physics, School of Applied Science, University of Science and Technology Beijing, Beijing, 100083, People’s Republic of China

    M. Zubair Iqbal

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  1. Mujtaba Ellahi
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  2. Fang Liu
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Correspondence to Hui Cao or Huai Yang.

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Ellahi, M., Liu, F., Song, P. et al. Influence of the multi-functional epoxy monomers structure on the electro-optical properties and morphology of polymer-dispersed liquid crystal films. Polym. Bull. 70, 2967–2980 (2013). https://doi.org/10.1007/s00289-013-1000-6

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  • DOI: https://doi.org/10.1007/s00289-013-1000-6

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