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Simple molecular building blocks, arranged in a repeating manner with hierarchical levels of organization, may lead to emergent functional properties, which would not otherwise be exhibited by the building blocks alone. The design principles of periodicity and hierarchical order are pervasive in nature, and have been borrowed to engineer man-made materials with functionality beyond their component parts. This thesis explores the development and application of block copolymers as templates for the fabrication of functional nanostructures. The core linear diblock copolymer may be pre- or post-functionalized with elements such as semiconducting moieties, topochemical precursors, and biomolecules. Periodicity is observed in the highly-ordered packing of the small molecules and patterns resulting from the cooperative self-assembly of the block copolymers and small molecules. The collective order of periodic structures at multiple lengths scales, ranging from the nanometer to micrometer regime, leads to the fabrication of hierarchical systems. These findings contribute to the critical development of complex architectures and understanding their structure-property relationships.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Includes bibliographical references. / by Frank Steven Bates. / Sc.D.

archives@tulane.edu / Silicon-based block copolymers have gained prominence because of their inherent ability to self-assemble at the low molecular weight. By utilizing this vital factor, we synthesize poly(vinylmethylsiloxane-block-methyl methacrylate) (PVMS-b-PMMA) intending to create small characteristic features with the potential application for lithography and membrane filtration. The polymer is made by a combination of anionic synthesis of PVMS, ATRP (atom radical transfer polymerization) of PMMA, and then cojoining the end-group functionalized blocks with a “click” reaction. After synthesis, thin films (10-100 nm) were self-assembled to form structures aligned perpendicular to the substrate. The morphology was observed by atomic force microscopy, grazing incidence small-angle X-ray scattering (GISAXS), and transmission electron microscopy (TEM). Additionally, the hydrophobicity of PVMS prompted us to develop a coating on microporous membrane supports for separation of water-in-oil mixtures. The PVMS was used as an effective coating to prevent fouling while maintaining high selectivity for both water-in-toluene and water-in-decane emulsion in gravity-based filtration. Finally, cyclic block copolymers (BCPs) have garnered increased attention because of their unique structure, which differs from linear BCPs due to a lack of end groups. This feature in combination with the high segregation strength of silicon-based polymers is desirable for nanolithography. Thus, we synthesized a new class of silicon-based cyclic polymer, cyclic PVMS-b-PMMA, intending to later understand the impact of topology on phase behavior, domain spacing, and nanoconfinement in thin films. / 1 / Baraka Lwoya

Cell membranes, or plasma membranes, play an essential role in the structure and the function of living cells. In 1972, the fluid mosaic membrane model was the first unifying paradigm of membrane structure. It is no longer considered adequate because evidence of many non-homogeneous lipid structures in both natural and model membranes have been discovered over the past thirty years. The field of membrane biophysics now uses updated versions of the mosaic model, which consists of the complex mixture of different lipid species. The lipid species found in natural membranes produce a range of dynamic, laterally segregated, non-homogeneous domains, which exist on time scales ranging from microseconds to minutes. The cell membrane is an enclosing or separating membrane that acts as a selectively permeable barrier within living things. It consists of the phospholipid bilayer with associated embedded proteins, integral (intrinsic) and peripheral (extrinsic) proteins used for various biological activities. Proteins, especially integral membrane proteins, perform a range of key functions vital to the cell, such as controlled movement of molecules across lipid bilayers, as well as participating in cell signaling and motility. The major obstacle to studying membrane proteins is the tendency for some of their properties to change and the proteins themselves may be denatured when extracted by detergents. One of the most significant approaches to solve this problem is the use of styrene-maleic acid copolymers (SMAs), which offers detergent-free solubilization of embrane, which allows studies of membrane proteins to be done in very small systems. The main goal of this thesis is to examine the effects of these polymers on the interior of the lipid bilayer. With these, membrane proteins can be extracted from cell membranes while conserving a patch of near-native membrane around them. It has been suggested but not proven that proteins in nanodiscs reside in a hydrophobic environment that is identical to that found in the native cell membrane. Moreover, I also investigate the kinetics of membrane solubilization by SMA by using UV/visible spectrophotometer. In addition, I examine how lipid packing in the nanodiscs is affected by the presence of the polymers and how it depends on polymer composition by using SMA variants with different styrene-to-maleic acid ratios.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (M.S.)--University of Florida, 2006. / Title from title page of source document. Document formatted into pages; contains 61 pages. Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaf 115). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Lehigh University, 2003. / Includes bibliographical references and vita.

Thesis (Ph. D.)--University of Rhode Island, 2000. / Typescript. Includes bibliographical references (leaves 123-138).