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Theory of Interacting Polyelectrolytes Under ConfinementEliseev, Alexander 01 May 2012 (has links)
During my thesis work I have investigated the problem of polyelectrolyte characterization and in particular how to interpret the experimental data to obtain the mass and gyration radius of short polyelectrolytes. This is usually a challenging problem for experimentalists to deal with. For example, the interpretation of the static light scattering data to obtain the gyration radius becomes increasingly inaccurate as the size of the chain becomes very much smaller then the light wavelength. Also, the interpretation of membrane osmomometry data is complicated by the leakage of the solute of low molecular weight polymers and so forth. There are, however, a number of approaches to deal with these problems.
In the first chapter of my thesis I obtained a crossover formula of the second virial coefficient of polyelectrolytes that correctly reproduces the perturbative and asymptotic polymer regimes in addition to the salt concentration dependence at high-to-medium salt concentrations. This formula will then be combined with similar crossover formula for the radius of gyration to interpret the later from the second virial coefficient measurement.
On the technical side of the story, the crossover formula was obtained by combining the renormalization group equation(to the first nontrivial order in epsilon) with the direct d=3 computation of the perturbative expansion( to the second order in the two coupling constants) obtained from double inverse Laplace transform.
The second chapter of my dissertation is about the translocation phenomena. Translocation is a phenomena of threading a polymer through narrow pores and/or channels. This is very promising technique to measure the molecular weight of every individual polymer in the solution. Indeed, the polymer chain threading through the pore blocks the flow of electric current that also flows through the pore. By the duration of the current blockade the length of polymer chain can be obtained.
Unfortunately, there are a number of problems this approach encounters. One of them is that the only so far practically obtainable nanometer-size pore is the alpha hemolysine one which has a complicated internal layout- a spherical(more or less) vestibule. This nasty feature makes current blockade vs time data harder to interpret. There is a way to bypass this problem. Recently a number of research groups began to modify the pore via the directed mutagenesis to reduce the time the chain spends in the vestibule.
In my work I theoretically investigated translocation of the polyelectrolyte chain through a spherical cavity with tunable charge. The results provide some guidelines on how to reduce the influence of the vestibule on the translocation time if we are to medify the chain in addition to the decorating the pore with charges. This work includes a number of interesting techniques. It is based on the self-consistent field theory which gives us nonlinear Schroedinger and Poisson-Boltzmann equations. These equations are then solved numerically via a finite difference schemes.
Lets point out possible extensions of this work. The SCFT technique is a primary computational tool for polyelectrolyte brushes and melts. Those things can be useful for the rapidly developing technology of pore gating, brush filtration and brush lubrication, just to name a few.
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The influence of polysaccharides on sub-surface soil properties and interactionsMourato, Diana January 1990 (has links)
Note:
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Effect of Metal Coating on NaYF<sub>4</sub>:Yb<sup>3+</sup>,Tm<sup>3+</sup> Upconversion NanoparticlesAlazemi, Abdulrahman Miteb 30 May 2014 (has links)
No description available.
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The Design and Synthesis of Aromatic Ion-Based Polyelectrolytes for Divergent ApplicationsFreyer, Jessica Leigh January 2018 (has links)
Versatile polyelectrolytes with tunable physical properties have the potential to be transformative in applications ranging from medicine to energy storage. To expand the design space for innovative cationic polymeric materials, I describe herein the development of a new class of functional polyelectrolyte based on the aromatic trisaminocyclopropenium (TAC) ion. The facile synthesis of a series of cyclopropeniumbased macromolecules via either the direct polymerization of functional monomers or a post-polymerization click reaction is demonstrated. To probe fundamental structureproperty relationships and understand technological implications of cyclopropenium polymers, a variety of materials were evaluated as gene delivery agents for cellular transfection and as ion conducting membranes. It was found that certain cyclopropenium polymers are biocompatible and efficient transfection agents, and that post polymerization functionalization chemistry enabled the straightforward screening of polymeric TAC derivatives. Furthermore, the thermal properties, local morphology, and dielectric response of a series of monomeric and polymeric TAC ionic liquids with different counter ions were characterized. It was found that the mechanism for ion transport depends on the nature of the ion pair, which can promote anomalously high conductivity at the calorimetric glass transition temperature. Finally, the synthesis of a new class of polyelectrolyte based on the cyclopentadienyl aromatic anion is described.
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Polyelectrolyte adsorption kineticsLang, Matthew H. 01 January 1994 (has links)
No description available.
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Chemical Synthesis and Ionic Conductivity of Water-Soluble Articulated Rigid-Rod Solid PolyelectrolytesChen, Chien-Chang 30 June 2003 (has links)
A water-soluble rigid-rod polyelectrolyte sPBI-PS(Li+) could be
doped with LiI and cast as a freestanding film from aqueous solution
showing a room-temperature in-plane DC conductivity (
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Effects of polyelectrolyte conformation, charge density and ion specificity in polyelectrolyte and polyelectrolyte-drug interaction /Hugerth, Andreas M. January 2000 (has links)
Thesis (Ph. D.)--Uppsala University, 2000. / "Acta Universitatis Upsaliensis." Extra abstract sheet inserted. Includes bibliographical references (p. 37-39).
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The role of polyelelectrolyte charge density and molecular weight on the adsorption and flocculation of colloidal silica with polyethylenimineLindquist, G. Michael January 1975 (has links) (PDF)
Thesis (Ph. D.)--Institute of Paper Chemistry, 1975. / Bibliography: leaves 178-186.
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Polyelectrolyte multilayer films containing nanocrystalline celluloseCranston, Emily D. January 2008 (has links)
In the past decade, electrostatic layer-by-layer (LBL) assembly has gained attention because it is a facile and robust method to prepare thin polymer films. Due to the industrial importance and natural abundance of cellulose, its incorporation into LBL films is of particular interest. This thesis examines the use of nanocrystalline cellulose, prepared by sulfuric acid hydrolysis of cotton, in polyelectrolyte multilayer films. Conventional solution-dipping and a spin-coating variant of LBL assembly both resulted in chemically defined, reproducible, and smooth films with adjustable properties. Surface morphology was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and film growth was monitored by X-ray photoelectron spectroscopy (XPS) and optical techniques. Orientation of the rod-like cellulose nanocrystals imparted anisotropic film properties, and birefringence was calculated from angle dependent and wavelength dependent optical reflectometry measurements. While spin-coating resulted in radial orientation of the nanocrystals, electrostatic adsorption in a magnetic field led to linear alignment. The internal structure, surface orientation and wettability of these materials were investigated. The attractive and repulsive forces acting close to the surface of the multilayer films in aqueous media were measured by colloid-probe AFM and the interaction forces between the film surfaces and charged colloidal-probes were compared to the predictions of the DLVO theory. The applications and advantages of polyelectrolyte multilayers containing nanocrystalline cellulose and their potential as model cellulose surfaces are discussed.
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Nickel-based 3D electrocatalyst layers for production of hydrogen by water electrolysis in an acidic mediumBou-Saleh, Ziad. January 2008 (has links)
This thesis discusses results on the development of three-dimensional (3D) Ni-based electrocatalytic layers for hydrogen production by water electrolysis in an acidic medium. This is of relevance to the development of polymer-electrolyte-membrane (PEM) hydrogen generators, which are promising hydrogen production systems suitable for both residential and industrial applications. / It was demonstrated that patterning of a glassy carbon electrode substrate with a 3D polyaniline (PANI) matrix is a convenient way of increasing the electrocatalytically active surface area of electrodeposited Ni, and hence its apparent electrocatalytic activity. The optimized PANI/Ni electrocatalyst layer showed a significantly higher activity in the hydrogen evolution reaction (HER) then a commercially available Ni-plate surface (control surface). / It was also demonstrated that it is possible to produce a Ni-based HER electrocatalyst layer by synthesizing Ni nanoparticles and supporting them on Vulcan carbon. This electrocatalyst also offered a significantly higher electrocatalytic activity in the HER then the control surface, but lower then the optimized PANI/Ni electrocatalyst. / The electrocatalytic activity of the optimized PANI/Ni layer was also compared to the activity of a 3D catalyst produced by electro-coating a porous reticulated vitreous carbon (RVC) substrate with Ni. This electrocatalyst showed the highest HER electrocatalytic activity among the investigated layers when tested under potentiodynamic polarization conditions. However, under the potentiostatic conditions, the optimized PANI/Ni layer showed the highest electrocatalytic activity. / The mechanisms and kinetics of the HER on the produced electrocatalysts was also investigated, as well as the electrocatalyst layers' surface morphology and crystalline structure.
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