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Yue Cui dissertation 20140724.pdf (8.65 MB)

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POLYMER’S ANCHORING BEHAVIOR IN LIQUID CRYSTAL CELLS

Cui, Yue
http://rave.ohiolink.edu/etdc/view?acc_num=kent1406515363

Abstract Details

2014, PHD, Kent State University, College of Arts and Sciences / Chemical Physics.
The current dissertation mainly discusses about the polymers anchoring behavior in liquid crystal cells in two aspects: surface interaction and bulk interaction. The goal of the research is to understand the fundamental physics of anchoring strength and apply the knowledge to liquid crystal display devices. Researchers proposed two main contributors to the surface anchoring strength: the micro grooves generated by external force and the polymer chain’s alignment. Both of them has experimental proofs. In the current study, explorations were made to understand the mechanisms of surface anchoring strength and easy axis of surface liquid crystal provided by rubbed polymer alignment layer. The work includes not only the variation of the alignment layer itself such as thickness(Chapter 3) and polymer side chain (Chapter 5), but also the variation of external conditions such as temperature (Chapter 4) and rubbing condition (Chapter 6). To determine the polar and azimuthal anchoring strengths, Rapini-Papoular’s expression was applied. However, it was discovered that higher order terms may be required in order to fit the experimental result or theoretically predict unique anchoring behaviors (Chapter 2, Chapter 6). SEM and AFM technologies were introduced to gather the actual structures of polymer alignment layer and extrapolate the alignment of liquid crystal in a micro scale. The result shows that the anchoring strength can be adjusted by the layer thickness, side chain structure, while the easy axis direction can be adjusted by a second rubbing direction. In addition, different anchoring conditions combined with liquid crystal's elastic energy can generate quite different forms of liquid crystals (Chapter 7). In the study of bulk alignment, the main contrition from the current dissertation is applying the understanding of anchoring behavior to optimizing actual switchable devices. Conventional PDLC performance can be tuned with the knowledge of the polymer and the liquid crystal’s interaction and proper selection of the materials (Chapter 5). Also, innovative micro structure can be designed and achieved, like the encapsulated PSCT (Chapter 8) which combines the merits of PDLC and PSCT. Such structure involves two separate polymer constructions. One is to encapsulate large droplets of cholesteric liquid crystal, while the other is inside the droplet to stabilize the cholesteric liquid crystal at transparent state. Thus the mixture has large viewing angle due to similarity to PSCT and is applicable to roll-to-roll manufacture.
Deng-Ke Yang (Advisor)
Philip Bos (Committee Member)
Hiroshi Yokoyama (Committee Member)
Hanbin Mao (Committee Member)
Robert Twieg (Committee Member)
229 p.
Physics
Liquid crystal, polymer, surface anchoring strength, Rapini-Papoular equation, PDLC, PSCT, encapsulation, diffusing sheet

Recommended Citations

Citations

  • Cui, Y. (2014). POLYMER’S ANCHORING BEHAVIOR IN LIQUID CRYSTAL CELLS [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1406515363

    APA Style (7th edition)

  • Cui, Yue. POLYMER’S ANCHORING BEHAVIOR IN LIQUID CRYSTAL CELLS. 2014. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1406515363.

    MLA Style (8th edition)

  • Cui, Yue. "POLYMER’S ANCHORING BEHAVIOR IN LIQUID CRYSTAL CELLS." Doctoral dissertation, Kent State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1406515363

    Chicago Manual of Style (17th edition)

kent1406515363
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© 2014, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.