The main object of this study is to explore the possibility of using metallocene catalyst and reagent toe preparation syndiotactic polystyrene (sPS) framework connected with different polymer segments. Despite its enhanced thermal stability, the stereo-regular sPS generally has poor miscibility with other conventional polymers, which substantially limits its use in commerce. Therefore, chemical modifications on sPS were attempted in this study to hopefully introduce polar chain segments into the olefinic sPS chains and to possibly vary its properties and so, its miscibility with other polymers. Here, a novel metallocene catalyst prepared from (

Zirconia is a metal oxide with high band gap. It is commonly used as catalysts in many industrial practices. In recent years, its high-energy-gap value and redox properties also render it as an excellent photocatalyst, which can eliminate or reduce a variety of pollutants. The purpose of this work is to prepare and characterize the chromium-doped ordered porous zirconia. The main purpose of doping chromium into the zirconia is to avoid the Martensitic transformation of zirconia under high temperatures by volume change and pore structure change, thus reducing the cracking and inferior mechanical properties. With emulsion-free polymerization for the synthesis of polystyrene (PS) particles, controlling the particle diameter less than 200 nm is possible. A polystyrene template is thus produced by gravity sedimentation of these PS particles. Final Cr-doped zirconia is obtained by infiltration of a precursor solution, a mixture consisting of zirconium n-propoxide, n-propanol, acetylacetone, and chromium (III) nitrate nonahydrate, into the PS template, followed by drying and calcination at elevated temperatures. A systematic study on the pore structure and physical properties by XRD and Raman is conducted by varying the precursor concentration, the calcination temperature, and the dopant concentration. The results show that, unlike the pure zirconia, the pore structure of Cr-doped zirconia remains stable under higher calcination temperatures. Without any phase transformation, the doped Cr, evidenced from the EDS mapping, tends to help stabilize the zirconia at tetragonal phase. The average surface area and pore diameter of Cr-doped zirconia from BET measurement are 19 ~ 21 m2/g and 25 -45 nm, far better than the bulk zirconia. The improved surface properties are also confirmed by SEM observations.

<p>This project involves the fabrication and testing of microporous, polymer membranes designed to remove minute amounts of toxic air pollutants such as formaldehyde from air streams. The hypothesis to be tested is that active, the silver contained within the porous polymer membranes results in high formaldehyde retention.</p><p>Monolayers consist of different sizes of sPS particles are assembled first on the silicon wafers by spin coating method and convective assembly method, respectively. Then each kind of monolayer with one dimension of sPS particles is deposited with a nanometer scaled silver thin film with a bench top metal evaporator. The porous membranes are produced by assembly of close-packed colloidal crystals of silver capped polystyrene template particles and subsequent infiltration with polyurethane prepolymer. The prepolymer is cured by UV exposure. The sPS particles are removed from the particle polymer membrane by treatment with organic solvents resulting in the formation of inverse opal structures. Silver does not dissolve in the organic solvents and cannot leave the pores due to the small size of connecting holes in an inverse opal. All the monolayers, cylindrical colloidal crystals and microcapillaries after infiltration of polyurethane had been characterized by optical microscope, and the porous membranes had been characterized by SEM.</p><p>The application of porous membranes with silver caps is to absorb formaldehyde in the air, while in fact the silver caps are oxidized and become Ag2O, which will initiate a gas-phase/solid reaction with formaldehyde. In the future, TiO2 will be applied together with Ag2O, since TiO2 is another good absorbent for formaldehyde</p>

Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Engineering, 2009. / "May, 2009." Title from electronic dissertation title page (viewed 11/27/2009) Advisor, Avraam I. Isayev; Committee members, James L. White, Thein Kyu, Kevin Kreider, Shi-Qing Wang; Department Chair, Sadhan C. Jana; Dean of the College, Stephen Cheng; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Title from PDF title page (viewed Jan. 28, 2010). Additional advisors: Derrick R. Dean, Wiliam K. Nonidez, Andrei Stanishevsky, Charles L. Watkins. Includes bibliographical references.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1965.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1964. / Includes bibliographical references (leaves 82-83).

This research project investigated the physical aging of glassy polymers in confined environments. Many recent studies of aging in glassy polymers have observed that aging behavior is often strongly affected by confinement. Understanding aging in confined environments (e.g., thin polymer films and nanocomposites) is vital for predicting long-term performance in applications that use confined glassy polymers, such as gas separation membranes and advanced nanocomposite materials. Aging in bulk and layered films produced via layer-multiplying co-extrusion was studied using gas permeability measurement and differential scanning calorimetry (DSC). The layered films consisted of polysulfone (PSF) and a rubbery co-layering material, with PSF layers ranging in thickness from ~185 nm to ~400 nm. Gas permeation aging studies at 35 °C revealed that the PSF layers in layered films aged in a manner that was similar to bulk PSF and independent of layer thickness. This finding differs from what was observed previously in freestanding PSF films, in which aging depended strongly on thickness and was accelerated relative to bulk. Isothermal aging studies at 170 °C and cooling rate studies were performed on both bulk and layered samples using DSC. The aging of the PSF layers was similar to aging in bulk PSF for films having PSF layer thicknesses of ~640 nm and ~260 nm, while the film with 185 nm PSF layers showed a slightly higher aging rate than that of bulk PSF. The results of the DSC studies generally support the conclusions of our gas permeation aging studies. The absence of strong thickness dependence in aging studies of layered films tends to support the idea that the effect of film thickness on physical aging stems from interfacial characteristics and not merely thickness per se. The physical aging of thin polystyrene (PS) films at 35 °C was also investigated using gas permeation techniques. PS films of 400 nm and 800 nm did not exhibit aging behavior that was highly accelerated relative to bulk or strongly dependent on film thickness. At the thicknesses and aging temperature considered, the aging of PS shows much weaker thickness dependence than that seen in polymers like PSF and Matrimid. / text

The development of analytical tools for investigating biological pathways on the molecular level has provided insight into diseases and disorders. However, many biological analytes such as glucose and inositol phosphate(s) lack the optical or electrochemical properties needed for detection, making molecular sensing challenging. Scintillation proximity assay (SPA) does not require analytes to possess such properties. SPA uses radioisotopes to monitor the binding of analytes to SPA beads. The beads contain scintillants that emit light when the radiolabeled analytes are in close proximity. This technique is rapid, sensitive and separation-free. Conventional SPA beads, however, are large relative to the cells and made of hydrophobic organic polymers that tend to aggregate or inorganic crystals that sediment rapidly in aqueous solution, thus limiting SPA applications. To overcome these problems, polystyrene core-silica shell nanoparticles (NPs) doped with pTP and dimethyl POPOP were fabricated to produce scintillation NPs that emit photons in the blue region of visible light. The developed scintillation particles are approximately 250 nm in diameter (i.e. 200 nm of core diameter and 10-30 nm of shell thickness), responsive to β-decay from tritium (³H) and have sufficient stability in the aqueous media. DNA hybridization-based SPA was performed to determine whether the scintillation NPs could be utilized for SPA applications. A 30-mer oligonucleotide was immobilized on the polystyrene core-silica shell NPs to give approximately 7.6 x 10³ oligonucleotide molecules per NP and ³H-labeled complementary strand was annealed to the immobilized strand. At the saturation point, increases in scintillation signal due to oligonucleotide binding to the NPs were about 9 fold compared to the control experiments in which no specific binding occurred, demonstrating that the scintillation NPs can be utilized for SPA. Along with the improved physical properties including smaller size and better stability in the aqueous system, the developed scintillation NPs could be potentially useful as biosensors in cellular studies.

No description available.