Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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2013 - 20183

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    Casimir-Lifshitz forces and torques
    (2018) Somers, David Andrew Templeton; Munday, Jeremy N; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Quantum electromagnetic field fluctuations result in the well-documented Casimir-Lifshitz force between macroscopic objects. If the objects are anisotropic, theory predicts a corresponding Casimir-Lifshitz torque that causes the objects to rotate and align. In this work, we report the first measurements of the Casimir-Lifshitz torque, which confirm the predictions first made decades ago. The experimental design uses a nematic liquid crystal separated from a birefringent crystal by an isotropic Al2O3 layer with a thickness
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    Dielectric studies of Liquid Crystal Nanocomposites and Nanomaterial systems.
    (2016) Kempaiah, Ravindra; Nie, Zhihong; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Liquid crystals (LCs) have revolutionized the display and communication technologies. Doping of LCs with inorganic nanoparticles such as carbon nanotubes, gold nanoparticles and ferroelectric nanoparticles have garnered the interest of research community as they aid in improving the electro-optic performance. In this thesis, we examine a hybrid nanocomposite comprising of 5CB liquid crystal and block copolymer functionalized barium titanate ferroelectric nanoparticles. This hybrid system exhibits a giant soft-memory effect. Here, spontaneous polarization of ferroelectric nanoparticles couples synergistically with the radially aligned BCP chains to create nanoscopic domains that can be rotated electromechanically and locked in space even after the removal of the applied electric field. The resulting non-volatile memory is several times larger than the non-functionalized sample and provides an insight into the role of non-covalent polymer functionalization. We also present the latest results from the dielectric and spectroscopic study of field assisted alignment of gold nanorods.
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    Novel Interactions of Liquid Crystals with Coated Nanoparticles
    (2013) Taylor, Jefferson; Martinez-Miranda, Luz J; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Functionalized nanoparticles have a wide range of applications in liquid crystal systems, including displays, photovoltaics, and drug delivery. We need to understand the interactions between the nanoparticles and the liquid crystal molecules in order to utilize them fully and safely. We investigate the short-range interaction of coated nanoparticles with a liquid crystal membrane or bulk sample through the use of atomic force microscopy (AFM) and X-ray scattering techniques. We identify the role the functionalization plays in the phase behavior of the liquid crystal both as a thin film and in bulk. Our research produced three results. We identify differing behavior in thin film samples of liquid crystal and coated nanoparticles dependent upon particle functionalization using AFM. Using X-ray scattering we measure the alignment and smectic layer formation in the presence of coated nanoparticles, even above the smectic-A to nematic transition temperature. We find evidence of a "halo" that forms around coated nanoparticles, particularly with longer coating molecules.