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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthesis, characterization and pharmaceutical application of selected copolymer nanoparticles / D.P. Otto

Otto, Daniël Petrus January 2007 (has links)
A multidisciplinary literature survey revealed that copolymeric nanoparticles could be applied in various technologies such as the production of paint, adhesives, packaging material and lately especially drug delivery systems. The specialized application and investigation of copolymers in drug delivery resulted in the synthesis of two series of copolymeric materials, i.e. poly(styrene-co-methyl methacrylate) (P(St-co-MMA)) and poly(styrene-co-ethyl methacrylate) (P(St-co-EMA)) were synthesized via the technique of o/w microemulsion copolymerization. These copolymers have not as yet been utilized to their full potential in the development of new drug delivery systems. However the corresponding hydrophobic homopolymer poly(styrene) (PS) and the hydrophilic homopolymer poly(methyl methacrylate) (PMMA) are known to be biocompatible. Blending of homopolymers could result in novel applications, however is virtually impossible due to their unfavorable mixing entropies. The immiscibility challenge was overcome by the synthesis of copolymers that combined the properties of the immiscible homopolymers. The synthesized particles were analyzed by gel permeation chromatography combined with multi-angle laser light scattering (GPC-MALLS) and attenuated total reflectance Fourier infrared spectroscopy (ATR-FTIR). These characterizations revealed crucial information to better understand the synthesis process and particle properties i.e. molecular weight, nanoparticle size and chemical composition of the materials. Additionally, GPC-MALLS revealed the copolymer chain conformation. These characterizations ultimately guided the selection of appropriate copolymer nanoparticles to develop a controlled-release drug delivery system. The selected copolymers were dissolved in a pharmaceutically acceptable solvent, tetrahydrofuran (THF) together with a drug, rifampin. Solvent casting of this dispersion resulted in the evaporation of the solvent and assembly of numerous microscale copolymer capsules. The rifampin molecules were captured in these microcapsules through a process of phase separation and coacervation. These microcapsules finally sintered to produce a multi-layer film with an unusual honeycomb structure, bridging yet another size scale hierarchy. Characterization of these delivery systems revealed that both series of copolymer materials produced films capable of controlling drug release and that could also potentially prevent biofilm adhesion. / Thesis (Ph.D. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2008.
2

Synthesis, characterization and pharmaceutical application of selected copolymer nanoparticles / D.P. Otto

Otto, Daniël Petrus January 2007 (has links)
A multidisciplinary literature survey revealed that copolymeric nanoparticles could be applied in various technologies such as the production of paint, adhesives, packaging material and lately especially drug delivery systems. The specialized application and investigation of copolymers in drug delivery resulted in the synthesis of two series of copolymeric materials, i.e. poly(styrene-co-methyl methacrylate) (P(St-co-MMA)) and poly(styrene-co-ethyl methacrylate) (P(St-co-EMA)) were synthesized via the technique of o/w microemulsion copolymerization. These copolymers have not as yet been utilized to their full potential in the development of new drug delivery systems. However the corresponding hydrophobic homopolymer poly(styrene) (PS) and the hydrophilic homopolymer poly(methyl methacrylate) (PMMA) are known to be biocompatible. Blending of homopolymers could result in novel applications, however is virtually impossible due to their unfavorable mixing entropies. The immiscibility challenge was overcome by the synthesis of copolymers that combined the properties of the immiscible homopolymers. The synthesized particles were analyzed by gel permeation chromatography combined with multi-angle laser light scattering (GPC-MALLS) and attenuated total reflectance Fourier infrared spectroscopy (ATR-FTIR). These characterizations revealed crucial information to better understand the synthesis process and particle properties i.e. molecular weight, nanoparticle size and chemical composition of the materials. Additionally, GPC-MALLS revealed the copolymer chain conformation. These characterizations ultimately guided the selection of appropriate copolymer nanoparticles to develop a controlled-release drug delivery system. The selected copolymers were dissolved in a pharmaceutically acceptable solvent, tetrahydrofuran (THF) together with a drug, rifampin. Solvent casting of this dispersion resulted in the evaporation of the solvent and assembly of numerous microscale copolymer capsules. The rifampin molecules were captured in these microcapsules through a process of phase separation and coacervation. These microcapsules finally sintered to produce a multi-layer film with an unusual honeycomb structure, bridging yet another size scale hierarchy. Characterization of these delivery systems revealed that both series of copolymer materials produced films capable of controlling drug release and that could also potentially prevent biofilm adhesion. / Thesis (Ph.D. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2008.
3

Synthesis, characterization and pharmaceutical application of selected copolymer nanoparticles / D.P. Otto

Otto, Daniël Petrus January 2007 (has links)
A multidisciplinary literature survey revealed that copolymeric nanoparticles could be applied in various technologies such as the production of paint, adhesives, packaging material and lately especially drug delivery systems. The specialized application and investigation of copolymers in drug delivery resulted in the synthesis of two series of copolymeric materials, i.e. poly(styrene-co-methyl methacrylate) (P(St-co-MMA)) and poly(styrene-co-ethyl methacrylate) (P(St-co-EMA)) were synthesized via the technique of o/w microemulsion copolymerization. These copolymers have not as yet been utilized to their full potential in the development of new drug delivery systems. However the corresponding hydrophobic homopolymer poly(styrene) (PS) and the hydrophilic homopolymer poly(methyl methacrylate) (PMMA) are known to be biocompatible. Blending of homopolymers could result in novel applications, however is virtually impossible due to their unfavorable mixing entropies. The immiscibility challenge was overcome by the synthesis of copolymers that combined the properties of the immiscible homopolymers. The synthesized particles were analyzed by gel permeation chromatography combined with multi-angle laser light scattering (GPC-MALLS) and attenuated total reflectance Fourier infrared spectroscopy (ATR-FTIR). These characterizations revealed crucial information to better understand the synthesis process and particle properties i.e. molecular weight, nanoparticle size and chemical composition of the materials. Additionally, GPC-MALLS revealed the copolymer chain conformation. These characterizations ultimately guided the selection of appropriate copolymer nanoparticles to develop a controlled-release drug delivery system. The selected copolymers were dissolved in a pharmaceutically acceptable solvent, tetrahydrofuran (THF) together with a drug, rifampin. Solvent casting of this dispersion resulted in the evaporation of the solvent and assembly of numerous microscale copolymer capsules. The rifampin molecules were captured in these microcapsules through a process of phase separation and coacervation. These microcapsules finally sintered to produce a multi-layer film with an unusual honeycomb structure, bridging yet another size scale hierarchy. Characterization of these delivery systems revealed that both series of copolymer materials produced films capable of controlling drug release and that could also potentially prevent biofilm adhesion. / Thesis (Ph.D. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2008.
4

Investigation into non-aqueous remedial conservation treatments for iron-tannate dyed organic materials

Wilson, Helen Louise January 2013 (has links)
Iron-tannate dyes have been used for thousands of years and on many continents to colour materials that are now part of our cultural heritage shades of black, grey, or brown. Cellulosic and proteinaceous yarns and woven textiles have been dyed with iron-tannate dyes to form objects or components of objects for domestic and ceremonial use. Unfortunately, the longevity and useful lifetime of iron-tannate dyed objects is threatened by the dye itself which accelerates the degradation of organic materials through metal-catalysed oxidation and acid-catalysed hydrolysis. The accelerated degradation causes weakening, discolouration, and embrittlement of the organic materials at a faster rate than undyed equivalents and if left unimpeded, weakens the objects to the point that they are no longer able to be exhibited without damage. In some cases the degradation is so great that the dyed areas of the objects have crumbled to dust. At present there is no suitable chemical stabilisation method available with which to inhibit this degradation. An aqueous treatment is available for successfully stabilising paper containing iron gall ink; iron gall ink is chemically similar to iron-tannate dye. However, the aqueous nature of this treatment makes it unsuitable for weakened fibres, water soluble components, and water sensitive materials which may be part of a composite material containing iron-tannate dye. Non-aqueous treatments are therefore urgently needed in order to preserve our iron-tannate dyed cultural heritage for future generations.In this project a range of non-aqueous antioxidants and a non-aqueous deacidifier (described in Chapter 8) were tested alongside existing aqueous treatment in order to establish their ability to slow down the degradation of a range of model iron-tannate dyed textiles (Chapters 9 and 10). Model textiles were developed as part of the project (Chapters 3-5) to be substitutes for historic materials in these stabilisation studies. Validation of the model textiles for this purpose (Chapter 6) involved the comparison of the model textiles with selected historic iron-tannate dyed objects within the British Museum’s collection (Chapter 6). The historic objects and the properties of the model textiles before and after accelerated ageing (Chapters 5 and 6) and before and after treatment application (Chapters 9 and 10) have been characterised using a variety of analytical techniques (Chapter 2). In order to determine which accelerated ageing conditions were the most suitable for this project various combinations of elevated temperature and either cycling or stable relative humidity were tested for their ability to produce noticeable changes in the properties of the dyed model textiles within four weeks of ageing (Chapter 7). This project is an AHRC/EPSRC funded Science and Heritage Programme PhD in which the British Museum has been a collaborative institution. Among other wider dissemination methods, research from this project has been presented to the public on numerous occasions at gallery tours and Science Day events at the British Museum.

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