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Liquid Crystals: Surfaces, Nanostructures, and Chirality

Nemitz, Ian R
http://rave.ohiolink.edu/etdc/view?acc_num=case1480686661255562

Abstract Details

2017, Doctor of Philosophy, Case Western Reserve University, Physics.
This dissertation focuses on liquid crystals (LCs), specifically their chiral properties and interactions with surfaces and nanostructures. Nematic twist cells were filled with a LC doped with the chiral molecule CB15, which compensates for the imposed twist. Using the electroclinic effect (ECE), results indicate that an ECE always exists near the surface in twist cells containing conformationally deracemizable molecules. ECE measurements were also performed to determine the source of the ECE response in a LC doped with chiral periodic mesoporous organosilica (PMO). The data show that the main source of the signal emanates from outside the PMO, and not inside the PMO pores. An ECE also is reported for chiral LCs above their bulk chiral isotropic – nematic phase transition, and is observable in the paranematic layers induced by the planar-aligning substrates. Optical microscopy measurements were performed on smectic-A oily streaks doped with CB15. When chirally doped, the stripe orientation rotated by a temperature dependent angle: This angle increased with concentration, was largest just below the nematic – smectic-A transition, and stabilized to near zero within ~1oC below TNA. This is explained as a manifestation of a surface ECE. Finally, a novel structure in a hybrid aligned system was observed below the smectic-A – smectic-C transition. The structure appeared as periodic dark and light streaks running perpendicular to the oily streaks, and formed by extending discretely from one oily streak to the next, eliminating optical evidence of the oily streaks. At lower temperatures the streaks undulated in a 2D chiral pattern. A possible origin of these streaks is presented.
Charles Rosenblatt (Advisor)
Emmanuelle Lacaze (Advisor)
Petschek Rolfe (Committee Member)
Peshek Timothy (Committee Member)
Selinger Robin (Committee Member)
Tin Padetha (Committee Member)
DiLisi Gregory (Committee Member)
Carles Pierre (Committee Member)
224 p.
Condensed Matter Physics; Physics
Liquid Crystals; Chirality; Electroclinic; Induced Surface Order; Phase Transitions; Defects

Recommended Citations

Citations

  • Nemitz, I. R. (2017). Liquid Crystals: Surfaces, Nanostructures, and Chirality [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1480686661255562

    APA Style (7th edition)

  • Nemitz, Ian. Liquid Crystals: Surfaces, Nanostructures, and Chirality. 2017. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1480686661255562.

    MLA Style (8th edition)

  • Nemitz, Ian. "Liquid Crystals: Surfaces, Nanostructures, and Chirality." Doctoral dissertation, Case Western Reserve University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1480686661255562

    Chicago Manual of Style (17th edition)

case1480686661255562
226
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This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.
Release 3.2.12