Contact antimicrobial coatings with poly-alkylammonium compositions have been a subject of increasing interest in part because of the contribution of biocide release coatings to antibiotic resistance. Herein, a concept for antimicrobial coatings is developed based on thermodynamically driven surface concentration of soft block side chains. The concept incorporates structural and compositional guidance from naturally occurring antimicrobial proteins and achieves compositional economy via a polymer surface modifier (PSM). For this purpose, polyurethanes having P[AB] co-polyoxetane soft blocks, where A is a surface active (fluorous) or PEG-like side chain and B represents a desired function (alkylammonium) were prepared. Specifically, poly(2,2-substituted-1,3-propylene oxide) ran-co-telechelics with bromobutoxymethyl (CH2O(CH2)4Br) and either trifluoroethoxymethyl (3FOx, -CH2OCH2CF3)) or PEG-like (2-(2-methoxyethoxy)ethoxy)methyl (ME2Ox, (-CH2(OCH2CH2) 2OCH3)) side chains were prepared via cationic ring opening polymerization. Characterization utilized 1H NMR spectroscopy, temperature modulated differential scanning calorimetry (MDSC) and thermogravimetric analysis (TGA). Molecular weights (Mn) by 1H NMR end group analysis were ~6000-8000g/mole. Bromobutoxymethyl groups were completely substituted with N,N-dimethylalkyl amines to obtain alkylammonium co-telechelics. Two alkyl ammonium chain lengths, six carbons (C6) and twelve carbons (C12) were used. Tgs of bromobutoxymethyl co-telechelics were -68 degrees C and -48 degrees C for ME2Ox and 3FOx, respectively. Tgs remained low after amine substitution. Alkylammonium co-telechelics decomposed at 220-230 degrees C regenerating amine. Telechelics were incorporated into polyurethanes (PUs) having 4,4'-(methylene bis (p-cyclohexyl isocyanate) (H12MDI) and butanediol (BD) as the hard block (30wt%). Characterization by 1H NMR, GPC, MDSC and TGA is described. From DSC data, using the Fox equation, the weight fraction of pure soft block in the soft block domain (w1) was very high (0.96-0.99) for polyurethanes with fluorous soft blocks, while soft blocks with PEG-like side chains were phase mixed (w1 = 0.73-0.75). To our knowledge, this is the first time that a polycationic telechelic has been incorporated into a polyurethane. By using X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR-IR) spectroscopy, dynamic contact angle (DCA) analysis, sessile drop measurement, and Tapping Mode Atomic Force Microscopy (TM-AFM), surface properties of polyurethanes were examined. These polyurethanes were co-processed with base polyurethanes to modify surfaces. Surface concentration of 2 wt % P[AB]-polyurethanes was studied by using the same surface characterization methods. Surface concentration of semifluorinated and alkylammonium side chains (C6 and C12) was observed. Miscibility of PEG-like side chains resulted in weak concentration of short alkyl ammonium side chains (C6). However, longer alkylammonium side chains (C12) can 'self-chaperone' and surface concentrate better compared to shorter side chain analogs. For biocidal testing, aerosol and touch tests were designed and implemented. Coatings were tested for zone of inhibition. The polyurethanes were first tested as 100 wt % coatings and found to be highly effective against both Gram(-) (Pseudomonas aeruginosa, Escherichia coli) and Gram(+) (Staphylococcus aureus) bacteria. Polyurethane modified surfaces (2 wt %) were tested against aerosol challenges of the same bacteria strains. The 2 wt % PSM with soft block containing trifluoroethoxy (A, 89 mol %) and C12 alkylammonium (B, 11mol %) side chains gave the highest biocidal effectiveness against all bacteria strains in 30 min (100% kill, 3.6-4.4 log reduction).

This thesis project has focused on the development of high-pressure single-crystal diffraction experiments on the neutron Laue diffractometer KOALA at the OPAL reactor at ANSTO, Australia. Over the course of this project several candidate systems have been studied under conditions of high-pressure using X-ray diffraction with a view to their use in developmental experiments on KOALA. The results of two high-pressure KOALA experiments are presented as well as the notable results from X-ray diffraction on the candidate systems. The first experiment on hexamethylenetetramine provided valuable insights into how reduced crystallite size and reciprocal-space access affects data collected on KOALA. In addition, data treatment techniques were developed to deal with the unique and challenging high-pressure Laue data, including corrections for attenuation due to the cell body. The ability to collect data through the body of cell prompted a further experiment on the complex, low-symmetry structure of the amino acid l-arginine dihydrate. Despite the smaller crystal size and dominant parasitic scattering from the diamond-anvil cell, the data collected allow a full anisotropic refinement of hexamethylenetetramine with bond lengths and angles that agree with literature data within experimental error. This technique is highly suited to low-symmetry crystals, as shown by the successful refinement of data from a l-arginine dihydrate crystal. In such cases the transmission of diffracted beams results in higher completeness values than are possible with X-rays. The hydrogen-bonded ferroelectric rubidium hydrogensulfate was the subject of ambient-pressure experiments on KOALA investigating the nature of the ferroelectric transition. Further high-pressure X-ray diffraction studies were carried out to resolve the structures of phases at high-pressure and to investigate the ferroelectric transition under pressure. The potassium cobalt citrate metal-organic framework UTSA-16 has shown a wide variety of pressure-mediated framework-solvent interactions including negative linear compressibility, the ordering of potassium ions, and coordination changes which were investigated by high-pressure single-crystal and powder X-ray diffraction. These behaviors are rationalised by examination of the structural changes occurring in the framework under pressure. Two members of the widely studied alkylammonium tetrachlorometallate family, tetramethylammonium tetrachloroferrate(III) and tetramethylammonium tetrachlorogallate(III), display numerous phase transitions with temperature. The structures of these phases have been determined for the first time, and the contrast between the two materials explored with first-principles calculations.

No description available.

Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium–modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium–modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium–modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium–modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

No description available.

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-05-12T18:07:41Z No. of bitstreams: 1 DissILM.pdf: 5724691 bytes, checksum: 47011a82c00569e1418ba50a076d335c (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-13T12:39:00Z (GMT) No. of bitstreams: 1 DissILM.pdf: 5724691 bytes, checksum: 47011a82c00569e1418ba50a076d335c (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-13T12:39:09Z (GMT) No. of bitstreams: 1 DissILM.pdf: 5724691 bytes, checksum: 47011a82c00569e1418ba50a076d335c (MD5) / Made available in DSpace on 2017-06-13T12:43:30Z (GMT). No. of bitstreams: 1 DissILM.pdf: 5724691 bytes, checksum: 47011a82c00569e1418ba50a076d335c (MD5) Previous issue date: 2016-02-15 / Não recebi financiamento / Nanosized NaX zeolites (FAU) (crystallite size = 16 nm; Si/Al ratio = 1,5) were synthesized and modified through ion exchange with linear alkylammonium cations containing from one to six carbons, with the intent to activate basic sites. In this work, commercial microsized zeolites (Aldrich) were also ion exchanged for comparison matters and all samples were characterized. Scanning electron microscopy analysis showed that both micro- and nanosized zeolites containing sodium portray polycrystalline particles: the former presents octahedral habit and particle size of 2952 nm and the latter presents an indefinite habit and particle size of 426 nm. Among the ion exchanged samples, none presented complete exchange of the Na+ cations due to steric hindrance. Nanosized zeolites presented higher exchange degrees than the microsized ones, which is due to higher accessibility to the exchange sites. Such factors also explain the exchange degrees’ reduction with the cations’ chain length, which is less abrupt among the nanosized samples. This happens due to the nanosized samples’ higher interparticular porosity, which has also allowed their micropore volumes’ constant decrease, differently from the microsized samples, which faced a minimum value with butylammonium. When the cations’ length is increased, the unit cell expands in comparison to the zeolites containing sodium since bulkier cations cause variations in the length and angle of the of the O-Si-O and O-Al-O bonds. Through thermogravimetric analysis in oxidant atmosphere, it was observed that the longer the carbon chain length, the lower is the mass loss, which evidences the lower diffusional limitations. The same was observed in inert atmosphere, which indicates that the presence of O2 does not influence the thermal events. Nanosized zeolites illustrate smoother mass loss profiles, which marks smaller diffusional limitations. The zeolitic materials were catalytically evaluated along the Knoevenagel condensation between butyraldehyde and ethyl cyanoacetate (3% m/m catalyst) during 1 h. The nanometric zeolites presented higher conversions and higher reaction rates when t = 0 than the microcrystalline ones, confirming the advantages of nanosized materials. / Zeólitas NaX (FAU) de cristais nanométricos (diâmetro de cristalito de 16 nm; razão molar Si/Al de 1,5) foram sintetizadas e modificadas através de troca iônica com cátions alquilamônio lineares de um a seis carbonos para a ativação de sítios básicos. No trabalho, efetuou-se também a troca iônica com zeólitas de cristais micrométricos (Aldrich) para fins de comparação, caracterizando-se todas as amostras. Por MEV, observou-se que as zeólitas sódicas micro- e nanométricas possuem partículas policristalinas, apresentando as primeiras hábito octaédrico e diâmetro de partícula de 2952 nm e, as últimas, hábito indefinido e diâmetro de 426 nm. Dentre as zeólitas trocadas, nenhuma apresentou troca completa dos cátions Na+ devido a impedimentos estéricos. As zeólitas nanométricas apresentaram graus de troca superiores aos das micrométricas devido à maior acessibilidade aos sítios de troca. Tais fatores também justificam a redução do grau de troca com o aumento do comprimento do cátion de compensação, sendo essa redução muito mais suave entre as amostras nanométricas. Isto ocorre devido à maior porosidade interparticular das zeólitas nanométricas, a qual permitiu que os volumes de microporos dessas zeólitas fossem sempre decrescentes, diferentemente das amostras micrométricas que atingiram um valor mínimo com o cátion butilamônio. Aumentando-se o comprimento do cátion, observa-se a expansão da cela unitária em comparação às zeólitas com cátion sódio pois cátions mais volumosos provocam variações no comprimento e nos ângulos das ligações O-Si-O e O-Al-O. Por análise termogravimétrica em atmosfera oxidante, observou-se que as zeólitas nanométricas exibem perfis de decomposição muito mais suaves, evidenciando as menores limitações difusionais. O mesmo foi observado em atmosfera inerte, indicando que a presença do O2 não influencia os eventos térmicos. Os materiais zeolíticos foram avaliados cataliticamente através da reação de condensação de Knoevenagel entre butiraldeído e cianoacetato de etila (3% m/m de catalisador) por 1 h. As zeólitas nanométricas apresentaram maiores conversões e maiores velocidades de reação no tempo zero que as microcristalinas, confirmando-se as vantagens de materiais com dimensões nanométricas.

La génération des fréquences somme (SFG), une technique spectroscopique spécifique aux interfaces, a été utilisée pour caractériser les changements de la structure macromoléculaire du surfactant cationique chlorure de dodécyltriméthylammonium (DTAC) à l’interface silice/eau dans une plage de pH variant entre 3 et 11. Les conditions expérimentales ont été choisies pour imiter les conditions les plus communes trouvées pendant les opérations de récupération assistée du pétrole. Particulièrement, la silice a été étudiée, car elle est un des composantes des surfaces minérales des réservoirs de grès, et l’adsorption du surfactant a été étudiée avec une force ionique pertinente pour les fluides de la fracturation hydraulique. Les spectres SFG ont présenté des pics détectables avec une amplitude croissante dans la région des étirements des groupes méthylène et méthyle lorsque le pH est diminué jusqu’à 3 ou augmenté jusqu’à 11, ce qui suggère des changements de la structure des agrégats de surfactant à l’interface silice/eau à une concentration de DTAC au-delà de la concentration micellaire critique. De plus, des changements dans l’intensité SFG ont été observés pour le spectre de l’eau quand la concentration de DTAC augmente de 0,2 à 50 mM dans les conditions acide, neutre et alcaline. À pH 3, près du point de charge zéro de la surface de silice, l’excès de charge positive en raison de l’adsorption du surfactant cationique crée un champ électrostatique qui oriente les molécules d’eau à l’interface. À pH 7 et 11, ce qui sont des valeurs au-dessus du point de charge zéro de la surface de silice, le champ électrostatique négatif à l’interface silice/eau diminue par un ordre de grandeur avec l’adsorption du surfactant comme résultat de la compensation de la charge négative à la surface par la charge positive du DTAC. Les résultats SFG ont été corrélés avec des mesures de l’angle de contact et de la tension interfaciale à pH 3, 7 et 11. / Sum Frequency Generation (SFG), an interface specific spectroscopic technique, was used to characterize the changes in the macromolecular structure of the cationic surfactant dodecyltrimethylammonium chloride (DTAC) at the silica/water interface at pH values ranging from 3 to 11. The experimental conditions were selected to mimic conditions common during enhanced oil recovery operations. In particular, silica was studied since it is one of the most abundant mineral components of sandstone reservoirs, and surfactant adsorption was studied at an ionic strength (100 mM NaCl) relevant to hydraulic fracturing fluids. SFG spectra showed detectable peaks with increasing amplitude in the methylene and methyl stretching region when the pH was lowered to 3 or increased to 11, suggesting changes in the surfactant aggregate structure at the silica/water interface at a DTAC concentration above the critical micelle concentration. In addition, changes in the SFG intensity were observed for the water spectrum when increasing the DTAC concentration from 0.2 to 50 mM under acidic, neutral or alkaline conditions. At pH 3, near the point of zero charge of the silica surface, the excess positive charge due to adsorption of the cationic surfactant creates an electrostatic field that orients water molecules at the interface. At pH 7 and 11, which are above the point of zero charge of the silica surface, the negative electrostatic field at the silica/water interface decreases in magnitude with surfactant adsorption due to compensation of the negative surface charge by the positively charged DTAC. The SFG results were correlated with contact angle and interfacial tension measurements at pH 3, 7 and 11.