No description available.

The solubility parameters for ten fractions of Athabasca vacuum residue were calculated from molecular representations via group additivity methods. Two methods were used; Marrero-Gani and Fedors. The calculated parameters were compared between the fractions for consistency, and also compared with other literature sources. The results from the Marrero-Gani method were satisfactory in that the values were in the expected range and the results were consistent from fraction to fraction. The final stage of the work on group additivities was to estimate the solubility parameter values at the extraction temperature of 473 K, and then compare the solutes to the solvents. The solubility parameters of the solvents were calculated from correlations and from the molecular dynamic simulation; the latter method did not result in fulfilling values. The most reasonable solvent and solute solubility parameters were used to assess the utility of the solubility models to explain the trends. The solubility models were not suitable for these types of materials. Stability of heavy oil fractions undergoing mild thermal reactions were predicted computationally for limited sample cracked molecules.

No description available.

This thesis explores the evaporation kinetics of various polymer-solvent and binary solvent mixtures to explore possible connections between the solutions properties and their evaporation process. By looking at the evaporation of polymer-solutions and binary-solvent solutions, through the change in weight as the solvent evaporates and the evaporation rate of the evaporation process, potential connections could be found. The results indicate that the presence of polymers influence the solvent evaporation, with polystyrene (PS) generally accelerating and polymethyl methacrylate (PMMA) either decelerating or having minimal impact on evaporation rates. Binary solvent mixtures exhibited non-proportional increases in evaporation rates, suggesting complex intermolecular interactions, but no apparent patterns between their properties and deviation in the evaporation process. This would need further research to find possible connections to be able to predict the evaporation process. But these findings highlight the importance of understanding polymer-solvent compatibility and evaporation dynamics to enhance performance and to identify environmentally friendly solvents for organic photovoltaic (OPV) cell fabrication. / Detta examensarbete undersöker avdunstningskinetiken hos olika polymer-lösningsmedel och binära lösningsmedelsblandningar för att utforska möjliga samband mellan lösningarnas egenskaper och deras avdunstningsprocess. Genom att studera avdunstningen av polymer-lösningar och binära lösningsmedelslösningar, genom förändringen i vikt när lösningsmedlet avdunstar och avdunstningshastigheten, kan potentiella samband identifieras. Resultaten indikerar att närvaron av polymerer påverkar lösningsmedlets avdunstning, där polystyren (PS) generellt accelererar och polymetylmetakrylat (PMMA) antingen decelererar eller har minimal inverkan på avdunstningshastigheterna. Binära lösningsmedelsblandningar visade icke-proportionella ökningar i avdunstningstider, vilket tyder på komplexa intermolekylära interaktioner, men inga tydliga mönster mellan deras egenskaper och avvikelser i avdunstningsprocessen kunde identifieras. Ytterligare forskning behövs för att finna möjliga samband för att kunna förutsäga avdunstningsprocessen. Dessa fynd understryker vikten av att förstå polymer-lösningsmedelskompatibilitet och avdunstningsdynamik för att förbättra effektiviteten och kunna identifiera miljövänliga lösningsmedel för tillverkning av organiska solceller (OPV).

The present thesis explores the volumetric and transport properties of complex fluid mixtures under pressure in order to develop a better, more holistic understanding of the relationship between the volumetric properties, derived thermodynamic properties, and viscosity. To accomplish this broad objective, two different categories of fluid mixtures were examined using a combination of experimental data and models. These included base oils and their mixtures with polymeric additives, used in lubricants and ionic liquids, with cosolvent addition, for use in biomass and polymer processing. Experimental density data were collected using a variable-volume view-cell at pressures up to 40 MPa and temperatures up to 398 K. A unique high pressure rotational viscometer was developed to study the effect of pressure, temperature, and shear rate on viscosity while also allowing for the simultaneous examination of phase behavior. Viscosity data were collected at pressures up to 40 MPa, temperatures up to 373 K, and shear rates up to 1270 s-1. Experimental density and viscosity data were fit to a pair of coupled model equations, the Sanchez-Lacombe equation of state and the free volume theory respectively. From density, derived thermodynamic properties, namely isothermal compressibility, isobaric thermal expansion coefficient, and internal pressure, were calculated. By generating these models, viscosity could be viewed in terms of density, allowing for a direct link with thermodynamic properties. In the first part of the study, the effect of composition on density, thermodynamic properties, and viscosity was examined for base oils used in automotive lubricants. Six different base oils, four mineral oils and two synthetic oils, were studied to develop a better understanding on how the thermodynamic properties, particularly isothermal compressibility and internal pressure, vary with the concentration of cyclic molecules in the oil stock. Isothermal compressibility was found to decrease with cycloalkane content, while internal pressure increased. Additionally, the effect of two different polymeric additives on the volumetric properties and viscosity of a base oil composed of poly(α olefins) was examined. Both additives are polymethacrylate based, one with amine functionality, and are used as viscosity index modifiers in engine oils and automatic transmission fluids. The polymer with amine functionality was found to have a significant effect on internal pressure, seen as a large drop at high polymer concentration (7 mass percent), due to the addition of repulsive intermolecular interactions. In the second part of the study, six ionic liquids with the 1-alkyl-3-methylimidazolium cation and their mixtures with ethanol were examined. Two anions were used, chloride and acetate. The effect of ethanol addition on the derived thermodynamic properties and viscosity was studied in terms of chain length of the alkyl group on the cation. In addition, a method of estimating Hildebrand solubility parameter was employed, allowing for solubility parameter to be put in terms of pressure, temperature, and composition. The effect of cosolvent addition on the thermodynamic properties was changed by the length of the alkyl group on the cation. As the cation became bulkier, anion-cation interactions weakened, allowing for an increase in the anion-cosolvent interactions. / Doctor of Philosophy / The present thesis aims to understand both the density and viscosity of various fluid mixtures at high pressures and temperatures through both experiments and modeling. By studying these properties simultaneously, a more holistic view of a fluid can be developed to predict its usefulness for a specific application. This is especially important in the case of fluid mixtures, where, in addition to temperature and pressure, composition needs to be taken into account. To accomplish the experimental portion of this work, a new high pressure rotational viscometer was developed to measure viscosity as a function of temperature and pressure in conjunction with a preexisting technique for measuring density. This experimental data was used to create models, allowing for a better understanding of the effect of temperature, pressure, and composition on both density and viscosity along with certain thermodynamic properties. In the first part of the study, oils and additives used to make lubricants with automotive applications, such as engine oils and automatic transmission fluids, were studied. By studying the properties of these mixtures under pressure, a better understanding of how properties key to lubricant effectiveness are related to temperature, pressure, and composition can be developed. In the second part of the study, ionic liquids, salts with melting points below 100oC, and their mixtures with ethanol were studied. Ionic liquids have unique properties and have been studied for use in batteries, polymer processing, biomass processing, and gas capture. Due to the wide range of potential ionic liquids with various properties that can be made, these salts have been described as tailorable solvents. By adding an additional solvent, the resulting mixture can be tuned through temperature, pressure, and composition. Using the set of tools employed in the present work, important properties for process design were calculated. In particular, the Hildebrand solubility parameter was estimated as a function of temperature, pressure, and composition. The solubility parameter is a useful tool in predicting whether or not a material will dissolve in the solvent of choice.

Yes / Many in-vitro methods for prediction of skin permeability have been reported in literature. Cerasome electrokinetic chromatography is one of the most sophisticated approaches representing a maximum level of similarity to the lipid phase of the stratum corneum. One goal of this study was to investigate the affinity pattern of Cerasome and to compare it with the permeability profile of human skin. Another purpose was to study the applicability of Hansen solubility parameters for modelling skin permeation and to investigate the predictive and explanatory potential of this method. Visualisation in Hansen diagrams revealed very similar profiles of Cerasome electrokinetic chromatography retention factors and skin permeability coefficients. In both cases, the characteristic pattern with two clusters of highly retained or highly permeable substances could be shown to be mainly caused by two groups of compounds, one of them with high affinity to ceramides, fatty acids and lecithin and the other being more affine to cholesterol. If based on a sufficiently comprehensive experimental dataset, model-independent predictions of skin permeability data using three-component Hansen solubility parameters are able to achieve similar accuracy as calculations made with an Abraham linear free energy relationship model in which the compounds are characterized by seven physicochemical descriptors.

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease associated with high levels of tumour necrosis factor-alpha (TNF-a) in synovial fluid and synovial tissue (Saxne et al., 1989). Thalidomide is a proven inhibitor of the biological synthesis of TNF-a (Sampaio et al., 1991) and is believed to rely on this action for its suppression of the wasting of tissue which accompanies RA. Oral administration of thalidomide has proven to be effective in RA, but unacceptable side effects are easily provoked (Gutierrez-Rodriguez, 1984). Administration of thalidomide via the dermal route can down-regulate TNF-a production in and around the affected joint, and this without raising the systemic blood level to a problematical level. Based on thalidomide's physicochemical properties, it is unlikely that it can be delivered percutaneously at a dose required for RA. Therefore, we have embraced the idea of using N-alkyl analogues of thalidomide. The most important feature that an analogue of this compound might contribute is decreased crystallinity and increased lipophilicity. Ordinarily both these parameters should favour percutaneous delivery. The current study was primarily aimed at exploring the feasibility of percutaneous delivery of thalidomide and subsequently, three of its odd chain IV-alkyl analogues (methyl, propyl and pentyl) via physicochemical characterization and assessment of their innate abilities to diffuse through skin as an initial step towards developing a topical dosage form for the best compound. The biological activities, more specifically their potential to inhibit the production of TNF-a was determined for thalidomide and its N-alkyl analogues. In order to achieve the objectives, the study was undertaken by synthesizing and determining the physicochemical parameters of thalidomide and its N-alkyl analogues. A high level of crystallinity is expressed in the form of a high melting point and heat of fusion. This limits solubility itself, and thus also sets a limit on mass transfer across the skin. Generally, the greater a drug's innate tendency to dissolve, the more likely it is that the drug can be delivered at an appropriate rate across the skin (Ostrenga et al., 1971). Therefore, the melting points and heats of fusion were determined by differential scanning calorimetry. Aqueous solubility and the partition coefficient (relative solubility) are major determinants of a drug's dissolution, distribution and availability. N-octanollwater partition coefficients were determined at pH 6.4. Solubilities in water, a series of n-alcohols and mixed solvents were obtained, as well as the solubility parameters of the compounds in study. Secondly, in vitro permeation studies were performed from these solvents and vehicles using vertical Franz diffusion cells with human epidermal membranes. Thirdly, tumour necrosis factor-alpha (TNF-a) inhibition activities were assessed for thalidomide and its N-alkyl analogues. By adding a methyl group to the thalidomide structure, the melting point drops by over 100°C and, in this particular instance upon increasing the alkyl chain length to five -CH2- units the melting points decrease linearly. Heats of fusion decreased dramatically upon thalidomide's alkylation as well. Methylation of the thalidomide molecule enhanced the aqueous solubility 6-fold, but as the alkyl chain length is further extended from methyl to pentyl, the aqueous solubility decreased exponentially. The destabilization of the crystalline structure with increasing alkyl chain length led to an increase in lipophilicity and consequently an increase in solubility in nonpolar media. Log partition coefficients increased linearly with increasing alkyl chain length. Solubilities in a series of n-alcohols, methanol through dodecanol, were found to be in the order of pentyl > propyl > methyl > thalidomide. The N-alkyl analogues have more favourable physicochemical properties than thalidomide to be delivered percutaneously. The in vitro skin permeation data proved that the analogues can be delivered far easier than thalidomide itself. N-methyl thalidomide showed the highest steady-state flux through human skin from water, n-alcohols and combination vehicles. Thalidomide and its N-alkyl analogues were all active as TNF-a inhibitors. Finally, active as a TNF-a inhibitor, N-methyl thalidomide is the most promising candidate to be delivered percutaneously for treatment of rheumatoid arthritis, of those studied. / Thesis (PhD (Pharmaceutics))--PU for CHE, 1999.

Thesis (PhD (Pharmaceutics))--PU for CHE, 1999.

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease associated with high levels of tumour necrosis factor-alpha (TNF-a) in synovial fluid and synovial tissue (Saxne et al., 1989). Thalidomide is a proven inhibitor of the biological synthesis of TNF-a (Sampaio et al., 1991) and is believed to rely on this action for its suppression of the wasting of tissue which accompanies RA. Oral administration of thalidomide has proven to be effective in RA, but unacceptable side effects are easily provoked (Gutierrez-Rodriguez, 1984). Administration of thalidomide via the dermal route can down-regulate TNF-a production in and around the affected joint, and this without raising the systemic blood level to a problematical level. Based on thalidomide's physicochemical properties, it is unlikely that it can be delivered percutaneously at a dose required for RA. Therefore, we have embraced the idea of using N-alkyl analogues of thalidomide. The most important feature that an analogue of this compound might contribute is decreased crystallinity and increased lipophilicity. Ordinarily both these parameters should favour percutaneous delivery. The current study was primarily aimed at exploring the feasibility of percutaneous delivery of thalidomide and subsequently, three of its odd chain IV-alkyl analogues (methyl, propyl and pentyl) via physicochemical characterization and assessment of their innate abilities to diffuse through skin as an initial step towards developing a topical dosage form for the best compound. The biological activities, more specifically their potential to inhibit the production of TNF-a was determined for thalidomide and its N-alkyl analogues. In order to achieve the objectives, the study was undertaken by synthesizing and determining the physicochemical parameters of thalidomide and its N-alkyl analogues. A high level of crystallinity is expressed in the form of a high melting point and heat of fusion. This limits solubility itself, and thus also sets a limit on mass transfer across the skin. Generally, the greater a drug's innate tendency to dissolve, the more likely it is that the drug can be delivered at an appropriate rate across the skin (Ostrenga et al., 1971). Therefore, the melting points and heats of fusion were determined by differential scanning calorimetry. Aqueous solubility and the partition coefficient (relative solubility) are major determinants of a drug's dissolution, distribution and availability. N-octanollwater partition coefficients were determined at pH 6.4. Solubilities in water, a series of n-alcohols and mixed solvents were obtained, as well as the solubility parameters of the compounds in study. Secondly, in vitro permeation studies were performed from these solvents and vehicles using vertical Franz diffusion cells with human epidermal membranes. Thirdly, tumour necrosis factor-alpha (TNF-a) inhibition activities were assessed for thalidomide and its N-alkyl analogues. By adding a methyl group to the thalidomide structure, the melting point drops by over 100°C and, in this particular instance upon increasing the alkyl chain length to five -CH2- units the melting points decrease linearly. Heats of fusion decreased dramatically upon thalidomide's alkylation as well. Methylation of the thalidomide molecule enhanced the aqueous solubility 6-fold, but as the alkyl chain length is further extended from methyl to pentyl, the aqueous solubility decreased exponentially. The destabilization of the crystalline structure with increasing alkyl chain length led to an increase in lipophilicity and consequently an increase in solubility in nonpolar media. Log partition coefficients increased linearly with increasing alkyl chain length. Solubilities in a series of n-alcohols, methanol through dodecanol, were found to be in the order of pentyl > propyl > methyl > thalidomide. The N-alkyl analogues have more favourable physicochemical properties than thalidomide to be delivered percutaneously. The in vitro skin permeation data proved that the analogues can be delivered far easier than thalidomide itself. N-methyl thalidomide showed the highest steady-state flux through human skin from water, n-alcohols and combination vehicles. Thalidomide and its N-alkyl analogues were all active as TNF-a inhibitors. Finally, active as a TNF-a inhibitor, N-methyl thalidomide is the most promising candidate to be delivered percutaneously for treatment of rheumatoid arthritis, of those studied. / Thesis (PhD (Pharmaceutics))--PU for CHE, 1999.

Organic electronics based on π-conjugated semi-conductor raises new technology, such as organic film transistors, e-paper, and organic photovoltaic cells that can be implemented cost-effectively on large-area applications. Currently, the device performance is limited by low charge carrier mobility. Poly(3-hexylthiophene) (P3HT) and organic field effect transistors (OFET) is used as a model to investigate morphology of the organic film and corresponding electronic properties. In this thesis, processing parameters such as boiling points and solubility are controlled to impact the micro- and macro-morphology of the film to enhance the charge transport of the device. Alternative approach to improve ordering of polymer chains and increase in charge transport without post-treatment of P3HT solution is studied. The addition of high boiling good solvent to the relatively low boiling main solvent forms ordered packing of π-conjugated polymers during the deposition process. We show that addition of 1% of dichlorobenzene (DCB) to the chloroform based P3HT solution was sufficient to improve wetting and molecular structures of the film to increase carrier mobility. Systematic study of solvent-assisted re-annealing technique, which has potential application in OFET encapsulation and fabrication of top-contact OFET, is conducted to improve mobility of OFET, and, to suggest a cost-effective processing condition suitable for industrial application. Three process parameters: boiling point, polarity, and solubility are investigated to further understand the trend of film response to the solvent-assisted technique. We report the high boiling non-polar solvents with relatively high RED values promote highest improvement in molecular packing and formulate crystalline structure of the thin film, which increases the device performance.