Call number: LD2668 .T4 1978 R37 / Master of Science

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The surfmers sodium l l-rnethacryloyloxy undecanyl-I sulfate (MET) and sodium 11- crotonoyloxy undecanyl-I sulfate (CRO) were synthesized and purified. Both contain a sulfonate and polymerizable double bond connected by a hydrocarbon chain. Sodium 4-[ 11- (3-carboxypropionoyloxy)-undecyloxy] benzenesulfonate (PSA-MA) could not be synthesized successfully. MET and CRO were characterized by means of nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), thermal gravimetric analysis (TGA), determination of the critical micelle concentration (CMC), differential scanning calorimetry (DSC), and microscopy. MET and CRO displayed a liquid crystalline behavior. MET and CRO were used in combination with poly(diallyl dimethyl ammonium chloride) to form polyelectrolyte-surfactant complexes by common precipitation in water. These complexes were redissolved in methanol and cast in films. The cast films were investigated by wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) with regard to ordered mesomorphous phases. Due to the destabilization of the lyotropic phase, little order were observed in the complexes. MET was co-polymerized with styrene and methyl methacrylate, in different proportions, by means of free radical polymerization. The co-polymers were characterized by NMR and infrared spectroscopy (Ik) and analyzed by DSC, TGA and gel permeation chromatography (GPC). All analytical techniques showed that the co-polymers were synthesized successfully. TEM indicated a fine, lamellar micro-structure. / AFRIKAANSE OPSOMMING: Die polimeriseerbare sepe, natrium-ll-metakrieloloksi-undekaniel-l sulfaat (MET) en natrium-ll-krotonieloksi-undekaniel-l-sulfaat (CRO) is berei en gesuiwer. Beide bevat 'n sulfonaat en 'n polimeriseerbare dubbelbinding wat deur 'n koolwaterstofketting verbind word. Natrium-4-[11-(3-karboksipropionieloksi)-undekieloksi]-benseensulfaat (PSA-MA) kon nie suksesvol berei word me. MET en CRO is deur middel van kernmagnetieseresonansspektroskopie (KMR), elementele-analise (EA), termiesegravimetriese analise (TOA), kritiese miselkonsentrasie (CMC), differensieelskandeerkalorornetrie (DSC) en mikroskopie gekarakteriseer. Beide MET en CRO het 'n vloei-kristalgedrag getoon. MET en CRO is met poli(diallieldimetielammoniumchloried) gereageer om polyelektrolietseepkompleks te vorm deur presipitasie uit water. Die komplekse is in metanol opgelos en films daarvan gemaak. Die films is deur wyehoek X-straal diffraksie (WAXS) en kleinhoek X-straaldiffraksie (SAXS) ondersoek om geordende mesomorfiese fases te ondersoek. As gevolg van destabilisasie van die liotropiese fase is min orde in die komplekse gevind. MET is met stireen en metielmetakrilaat deur middel van vryeradikaalpolymerisasie gekopolimeriseer. Die kopolimere is deur middel van KMR- en infrarooispektroskopie (IR), DSC, TOA en gelpermeasiechromotagrafie (OPC) ondersoek. Al hierdie analitiese metodes het die suksesvolle sintese van die kopolimere bewys. Transmissie-elektronmikroskopie het die teenwoordigheid van 'n fyn, laminere mikro-struktuur bewys.

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Studies involving solids-stabilised foams have been limited and few have focused on the benefits of complex systems such as those involving mixtures of more than one surfactant. Little is known about the effectiveness of using mixed surfactant systems as foam stabilisers at the bulk level. The purpose of this project was to gain further understanding and insight into foam stability, on a bulk scale, in the absence, and in the presence, of solid colloidal particles, and for systems involving single or mixed surfactants. Foams were produced using sodium dodecyl sulphate (SDS), dodecanoic acid (DA), or a mixture of both surfactants at varying molar ratios. The surface tension at a given concentration, the limiting surface tension (at high concentrations), the critical micelle concentration, foamability and foam stability were all significantly affected by the molar ratio of SDS to DA. The initial pH of mixed surfactant solutions played a role in the shift of surface tension and CMC. The higher pH values, the lower surface activity, therefore resulted in higher surface tension. At a given pH, however, the mixed surfactant solutions with higher molar ratio of SDS to DA appeared to have lower CMC. The foam stabilising ability of colloidal dispersions of four hydrous metal oxides, namely hydrous iron oxide (formed by hydrolysis of Fe(III) solutions and referred to as HFO), hydrous zinc oxide (formed by hydrolysis of Zn(II) solutions and referred to as HZO), hydrous chromium oxide (formed by hydrolysis of Cr(III) solutions and referred to as HCO), and hydrous nickel oxide (formed by hydrolysis of Ni(II) solutions and referred to as HNO) were studied at varying concentrations. Generally foam stability increased as the solid concentration increased. Foams stabilised by HNO were found to be the most stable. Foams stabilised by HFO were found to be unstable regardless of the solid concentration. It is believed that the instability of such foams is primarily due to the large aggregated size of HFO flocs. The aggregate size of hydrous metal oxides was influenced by the concentration of NaOH used to hydrolyse the metal ion solution, and by sonication treatment immediately following solid formation. However, the final pH of the colloidal dispersions did not significantly change the aggregate size. Solids stabilised foams are believed to be highly dependent on the state of hydrophobicity of the solids used, and this is in turn controlled by adjustment of the pH dependent surface charge and potential. Electrophoretic mobility is a commonly used tool to probe the potential near the surface and was used in this thesis to determine the affect of surfactant adsorption (particularly from solutions containing mixtures of SDS and DA) on surface properties of the solids. The electrophoretic mobility of all hydrous metal oxide aggregates decreased as the concentration of SDS/DA increased. Specific adsorption was evident in all cases and resulted in charge reversal for most cases. Electrophoretic mobility data for surfactant adsorption, as a function of total surfactant concentration, was consistent with a three-stage model of surfactant adsorption involving (1) electrostatic adsorption, (2) cooperative adsorption and (3) surface saturation. The influence of surfactant adsorption on electrophoretic mobility was found to be consistent with models requiring the stabilising solids to be in a controlled state of flocculation, where the zeta potential (as probed by electrophoretic mobility) must be sufficiently high to prevent total flocculation of the solid and thus collapse of the foam, but sufficiently low that the solids have some degree of hydrophobicity such that they prefer to be only partially wetted (and thus reside at the air/water interface). The total percentage adsorption of SDS/DA surfactant mixtures on both hydrous iron oxide and hydrous nickel oxide was found to be independent of time. However, the proportion of adsorption due to SDS and DA was dependent on time. Moreover, the initial and final ratio of SDS to DA adsorption did not reflect their ratio in solution. SDS adsorbed, initially, to a greater extent that would be predicted from its solution concentration, but this trend was reversed after a period of time.

The role of the nonionic surfactant Tween 80 on the behavior of the therapeutic recombinant protein Factor VIII (rFVIII) was investigated at solid/liquid and air/water interfaces. In order to provide a model system to compare results obtained for the complicated rFVIII-Tween system, a well-characterized globular protein lysozyme was used. The experimental scheme involved the introduction of the protein and Tween to the adsorption substrate in different manners, either lysozyme Tween together or in sequence as lysozyme followed by Tween or vice versa. It was observed that the addition of Tween together with lysozyme reduced the amounts adsorbed at hydrophobic surfaces, while no such reduction was observed on hydrophilic surfaces. A high Tween concentration was required to effect the removal of the lysozyme molecules from the hydrophobic surface and Tween was not effective in removing lysozyme from the hydrophilic surface at any concentration. These results suggest that the Tween-surface interaction is important in determining lysozyme adsorption. Similar observations were made for the rFVIII-Tween system at hydrophobic and hydrophilic silica interfaces. In this case, the presence of interfacial and solution Tween together resulted in complete prevention of rFVIII adsorption. Electrostatic forces were observed to be play an important role in rFVIII adsorption. The rFVIII-Tween interactions at solid interfaces were also evaluated using intrinsic fluorescence and biological activity measurements. Results obtained with respect rFVIII adsorbed mass, and structure or biological activity change upon adsorption, were evaluated in parallel. This parallel evaluation suggested that rFVIII adsorption on hydrophilic, negatively charged surfaces is likely to be highly ordered and oriented in a manner that retains the solvent accessibility of the active sites in rFVIII. On the other hand, rFVIII may adsorb to hydrophobic surfaces in different orientations, with a likelihood of surface induced unfolding. rFVIII-Tween interaction at the air/water interface was investigated separately. Surface tension data recorded for rFVIII-Tween mixtures suggested that Tween dominated the air/water interface as the Tween concentration was increased. Reduced interface-induced unfolding was observed at high Tween concentrations. These results were also thought to contribute to the reduction in rFVIII aggregation typically observed as a result of exposure to the air/water interface. / Graduation date: 2006

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 167-174).

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisors: Eric W. Kaler, College of Engineering; and Abraham M. Lenhoff, Dept. of Chemical Engineering. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 42-44). Also available on the World Wide Web.

Ph.D.