The aim of this thesis is the study of protein resistant oligo(ethylene glycol) (OEG) self-assembled monolayers (SAMs) using in situ techniques, such as neutron reflectivity (NR), polarisation modulation infrared spectroscopy (PMIR) and small-angle x-ray scattering (SAXS). In order to elucidate the mechanisms that lead to the nonfouling properties of these SAMs, the SAM-water, protein-protein and protein-SAM interactions have been studied separately. NR measurements, focused on the solid-liquid interface between OEG SAMs and water, show clear evidence of an extended layer with reduced density water. The reduction in density is up to 10% compared to the bulk value, and extends up to 5 nm into the bulk. The effective area (density reduction x length) of this reduced density water layer did not significantly change when the temperature was reduced to 5°C. In a complementary study, the interaction of water with protein-resistant HS(CHV₂)₁₁(OCH₂CH₂)₃OMe monolayers was examined using in and ex situ PMIR. In particular, shifts in the position of the characteristic C-O-C stretching vibration were observed after the monolayers had been exposed to water. The shift in frequency increased when the SAM was observed in direct contact with a thin layer of water. It was found that the magnitude of the shift also depended on the surface coverage of the SAM. These results suggest a rather strong interaction of oligo(ethylene glycol) SAMs with water and indicate the penetration of water into the upper region of the monolayer. These findings indicate the presence of a tightly bound water layer at the SAM-water interface. Further NR studies of the interface between OEG SAMs and a highly concentrated protein solution revealed an oscillating protein density profile. A protein depleted region of about 4-5 nm close to the SAM was followed by a more densely populated region of 5-6 nm. These oscillations were then rapidly damped out until the bulk value was reached. The influence of temperature and salt concentration on the protein density profile was small, indicating a rather minor contribution of electrostatic interactions to the protein repulsive force. SAXS measurements of OEG coated gold colloids mixed with proteins in solution did also not show any pronounced salt concentration dependence of the colloid-protein interaction. The strong association of water with the SAM and the layer of tightly bound water, together with the lack of electrostatic repulsion, suggest that the adsorption of proteins is energetically hindered by the presence of a strongly bound hydration layer.

Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisors: John F. Rabolt and D. Bruce Chase, Dept. of Materials Science & Engineering. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, 2000. / Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 136-145).

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A regiÃo Nordeste do Brasil, com suas condiÃÃes de semi-Ãrido, tem sofrido devido aos altos Ãndices de evaporaÃÃo que apresenta. Tais Ãndices propiciam grandes perdas para a regiÃo, de uma forma geral, e mesmo para o paÃs. O presente trabalho estuda uma das ferramentas mais populares do mundo para controle da evaporaÃÃo em reservatÃrios superficiais - filmes monomoleculares de hexadecanol - e as conseqÃÃncias da sua aplicaÃÃo na qualidade da Ãgua. Foram utilizados reservatÃrios de 20m2 de Ãrea (Tanques Russos) construÃdos na EstaÃÃo AgrometeorolÃgica da Universidade Federal do CearÃ, Campus do Pici. Os experimentos compreenderam 03 anos de observaÃÃo onde foram avaliados a eficiÃncia do filme, uma correlaÃÃo estatÃstica entre a reduÃÃo da evaporaÃÃo e alguns fatores climatolÃgicos (velocidade do vento, umidade relativa do ar, radiaÃÃo lÃquida, radiaÃÃo global e temperatura do ar), a influencia da aplicaÃÃo do filme nas caracterÃsticas biÃticas (fungos, fitoplÃnctons, baterias e peixes) e abiÃticas (turbidez, temperatura da Ãgua, condutividade elÃtrica, pH e salinidade) da Ãgua. Foram ainda avaliadas a velocidade de dispersÃo do surfactante na superfÃcie lÃquida e alguns efeitos adversos como à formaÃÃo de estrias. Os resultados apontaram que o produto à capaz de reduzir a evaporaÃÃo em cerca de 40% nas condiÃÃes do estudo. Foi ainda visualizado no estudo estatÃstico que a velocidade do vento e a temperatura do ar apresentaram influencias estatisticamente significativas na reduÃÃo da evaporaÃÃo. No que diz respeito aos parÃmetros abiÃticos a aplicaÃÃo do filme sà trouxe alteraÃÃo significativa na temperatura da Ãgua. As espÃcies fitoplanctÃnicas avaliadas e os peixes nÃo sofreram influencia do surfactante tambÃm, entretanto, foi observada certa seletividade nos fungos e bactÃrias. / Brazilian Northeast region, with its Semi-Arid conditions, has suffered difficulties due to its high evaporation levels. This evaporation brings great losses to the region and, in consequence, to the country. The present work studies one of the world most popular tools to control evaporation in open pans â hexadecanol monomolecular films - and the consequences of its application in water quality. It was used open pans of 20m2 of area (Russian Pans) built on Agrometeorological Station of Cearà University in Fortaleza. The experiments takes 3 years where were evaluated the film effectiveness, the statistical correlation between the evaporation reduction and the weather conditions, and the influence of the film application on biotic (phytoplankton, bacteria, fungus and fishes) and abiotic (turbidity, temperature, electrical conductivity, pH and salinity) characteristics of the water. It was also evaluated the dispersion velocity of the surfactant and the formation of âstringsâ. Results show that the product is able to reduce evaporation in 40% in Semi-Arid conditions. It was also presented that wind velocity and air temperature have some influence on evaporation reduction. Concerning the abiotic parameters the film application just causes significant alteration in water temperature. Phytoplankton and fishes does not suffer influences of the surfactante also, but it was notice some selectivity in fungus and bacteria species.

No description available.

Organic thin films prepared from long-chain organothiols have been self-assembled on gold surfaces and their chemistry and structural properties studied by physical, electrochemical and spectroscopic methods. The mechanism of charge transfer across these organic thin films was of particular interest and was studied by combined spectroscopic and electrochelllical methods. The influences of chain length, terminal functional group I and sol vent on the electrochemical kinetics were studied. Evidence of a kinetic barrier to charge transfer pointed to a charge-diffusion mechanism across the organic thin films. An Infrared Reflection-Absorption Spectroscopy (IRRAS) method was developed to monitor the titration of acid functionalized films. The method compared favorably with the currently-used goniometry method because the IRRAS method was faster, less prone to operator bias, and provided structural information. / Ph. D.

Area selective atomic layer deposition (ASALD) is demonstrated to be a promising route to perform direct patterned deposition. In particular, methods to modify (or mask) the surface and process parameters to perform selective deposition of titanium dioxide have been developed and investigated in detail. Results indicated that self assembled monolayer based masking methodology posses significant limitations due to challenges associated with obtaining defect free monolayer and absence of traditional patterning techniques. On the other hand, polymer films based masking methodology offer a better alternative to perform ASALD. A number of factors that must be considered in designing a successful ASALD process based on polymer films were identified. These include: reactivity of polymer with ALD precursor, diffusion of ALD precursors through polymer mask and remnant precursor content in the polymer film during ALD cycling. Investigations suggested that ALD nucleation can be successfully blocked on polymer films that do not contain direct OH sites in their backbone. It was observed that sorption of water in the polymer film does not pose a serious limitation however; metal precursor diffusion through the polymer mask was identified as a critical parameter in determining the minimum required masking layer thickness for a successful ASALD process. In addition, a novel ASALD-based top surface imaging (TSI) technique has been developed. The ASALD-TSI process has demonstrated sharp contrast (etch barrier deposition vs exposure dose) and therefore offers the potential to overcome many of the challenges experienced with conventional TSI schemes.

Phosphonic acids are known to bind strongly to a variety of metal oxide surfaces. Phosphonic acids were designed in order to impart specific properties to the surface of a range of metal oxides upon formation of a monolayer. A large number of novel phosphonic acids were synthesized and fully characterized. The binding of phosphonic acids to the surface of several metal oxides, such as indium tin oxide (ITO) and barium titanate, was studied in detail and determined to be a mixture of bidentate and tridentate binding modes. The modification of several key surface properties of ITO by phosphonic acid modification was also studied. The work function of ITO could be increased or decreased with respect to unmodified ITO by controlling the dipole of phosphonic acids bound to the surface. Additionally, the surface energy could be substantially lowered by attaching phosphonic acids with non-polar terminal functional groups to the ITO surface. The ability to control these surface properties resulted in organic light-emitting diodes (OLEDs) which showed superior lifetimes and stability with respect to OLEDs incorporating ITO without a phosphonic acid monolayer. In addition, the binding of phosphonic acids to a number of other oxides, such as zinc oxide and zeolites, was also studied.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 197-202). Also available on the Internet.