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Liquid Crystal Polymers And Dendritic Liquid Crystals: Synthesis, Morphology, Rheology And Binary Mixtures

Dong, Shaosheng
http://rave.ohiolink.edu/etdc/view?acc_num=case1094584392

Abstract Details

2005, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science.
Liquid crystals are a group of unique functional materials showing stimuli responses. This dissertation focused on two general directions—synthesis and characterizations of liquid crystal and liquid crystal polymers. The synthesis includes the preparation of (1) side chain liquid crystal polysiloxane of various molecular weights, with cyano phenyl benzoate as mesogens, for miscibility, electrorheology and neutron scattering study; (2) deuterated 4-pentyl-4’-cyano biphenyl(d-5CB), used as the solvent for neutron scattering study; (3) hyperbranched liquid crystals based on dendritic polyols, with cyano biphenyl as the mesogens, for electrorheological study. In the miscibility study with binary mixtures of liquid crystal polysiloxane/low molar mass liquid crystals, the induced smectic phase was observed within certain composition ranges, when 4-pentyloxyl-4’-cyano biphenyl was used; while no new phase was present with the study on another series of mixtures with 4-pentyl-4’-cyano biphenyl, although exactly the same polymers were used. The induced new phase with 5OCB was confirmed with DSC thermal analysis, POM textures, X-ray study and finally, computer simulation. In neutron scattering part, d-5CB with high substitution ratio was used as the solvent with liquid crystal polysiloxane as the solute. The substitution ratio was high enough to yield enough contrast, which in return indicates the successful deuteration reactions (80% overall yield; 20% from literature). The chain confirmation measured by neutron scattering qualitatively matched that from electrorheological experiments. Electrorheological study was carried out with the dilute solutions of hyperbranched liquid crystals in 5CB, which gave the conformational anisotropy around 1.5. The modified Brochard theory (by our group) predicts no tumbling behavior with this system, which was confirmed in stress transient experiments.
Alex. Jamieson (Advisor)
202 p.
Liquid crystals; Synthesis; Polymerization; Binary mixtures; Rheology; and Dendritic liquid crystal.

Recommended Citations

Citations

  • Dong, S. (2005). Liquid Crystal Polymers And Dendritic Liquid Crystals: Synthesis, Morphology, Rheology And Binary Mixtures [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1094584392

    APA Style (7th edition)

  • Dong, Shaosheng. Liquid Crystal Polymers And Dendritic Liquid Crystals: Synthesis, Morphology, Rheology And Binary Mixtures. 2005. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1094584392.

    MLA Style (8th edition)

  • Dong, Shaosheng. "Liquid Crystal Polymers And Dendritic Liquid Crystals: Synthesis, Morphology, Rheology And Binary Mixtures." Doctoral dissertation, Case Western Reserve University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1094584392

    Chicago Manual of Style (17th edition)

case1094584392
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© 2004, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.