Temperature responsive polymeric gels modified with gold nanoparticles.
Item
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Title
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Temperature responsive polymeric gels modified with gold nanoparticles.
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Identifier
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AAI3213263
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identifier
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3213263
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Creator
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Kazimierska, Ewa Anna.
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Contributor
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Adviser: Malgorzata Ciszkowska
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Date
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2006
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Analytical
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Abstract
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Preparation and characterization of temperature-responsive N-isopropyl-acrylamide (NIPA) polymeric gels, modified with colloidal gold nanoparticles are described. New methodology for incorporation of gold nanoparticles into gel matrixes to obtain three-dimensional crosslinked polymeric phases with uniformly distributed gold particles was developed. Gold particles of various sizes were synthesized and introduced to NIPA-gels during the free radical polymerization. These modified gels combine characteristics of gold nanoparticles and thermoresponsive polymeric gels. They undergo discontinuous volume phase transition at approximately 32°C that results in a release of up to 97% of a solvent from the polymeric matrix; this temperature is independent of the presence of gold nanoparticles. These gels exhibit surface plasmon resonance characteristic for colloidal gold particles.;Characterization of gold modified NIPA polymeric gels was performed using electroanalytical methods supported by spectroscopic and optical techniques. Available potential window was determined and transport properties of the gels were studied in terms of diffusion of molecular probes. Main experimental approaches were steady state voltammetry and chronoamperometry with microelectrodes and cyclic voltammetry with regular size electrodes. The UV-vis spectroscopy and transmission electron microscopy were used to determine the size and size distribution of incorporated gold nanoparticles. Diffusion coefficients of 1,1'-ferrocenedimethanol in swollen gels with and without gold nanoparticles were identical within an experimental error; they were lower than those in solutions without polymeric network. They decreased when an increased weight percentage of a polymer in a gel. These two observations were explained in terms of the "obstruction" and "hydration" effects.;Effects of the volume phase transition of the diffusion properties of the gels and the composition of released liquids were investigated. The diffusion coefficient of 1,1'-ferrocenedimethanol was up to 600 times lower in a collapsed phase than that in a swollen gel. The concentration of the 1,1'-ferrocenedimethanol probe in expelled solutions was up to 30% smaller than that in swollen gels; the NIPA gel matrix specifically retained this organic probe.;The influence of ionic strength on temperature of the volume phase transition and transport properties of the gels were also investigated.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
