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The cloud-point curves for solutions of poly(acrylic acid) in 1,4-dloxane, 1,4-dloxane/water mixtures, tetrahydrofuran and tetrahydrofuran/water mixtures as a function of molecular weight and solvent composition were determined. These systems are unusual in that they exhibit three phase separation boundaries on raising the temperature from room temperature to 500K designated as pseudo-LCST (p-LCST), UCST and LCST behaviour respectively in order of Increasing temperature. Systems consisting of poly(acrylic acid) together with small chain poly(ethylene glycol)s and poly(propylene glycol)s In 1,4-dioxane were also studied and, in general, they exhibited simple LCST behaviour. Critical points for the pseudo-LCST phase separation boundary were determined for the higher molecular weight poly(acrylic acid)s in 1,4-dloxane, using the phase volume ratio method. The variation of the intrinsic viscosity of solutions below the pseudo-LCST was measured as a function of temperature increasing towards the phase separation boundary. The structure and possible complex formation in the system at temperatures below the pseudo-LCST were determined using laser raman spectroscopy. Preferential solvation studies, using light scattering techniques, were also made on the mixed solvent system 1,4-dioxane/water, from which data were obtained which could be compared with those derived from solution viscosity. The variation of the enthalpic interaction parameter, Xh, was determined from heat of dilution data derived from microcalorimetry experiments. The cloud-point curves for the poly(acrylic acid) In 1,4-dloxane system were compared to poly(N-isopropylacrylamide) in water, which exhibited simple LCST behaviour and aqueous solutions of poly(vinyl alcohol) which formed a closed-loop of immiscibility.

Catalytic partial oxidation of organic molecules is critically enabling for production of commodity and specialty chemicals. Metal and metal-oxide surfaces can facilitate specified selective oxidation routes, but concurrent unselective reactions also occur. Minimizing the profusion of deleterious pathways through increasing selectivities of target oxidation products offers economic and environmental benefits. Although unselective oxidation of some molecules, such as ethylene, produces almost exclusively CO2, multiple organic byproducts of varying size (C1-C7+) are formed in appreciable quantities during oxidations of other molecules such as acrolein. Along with decreasing overall process yield, these byproducts lead in many cases to difficulties in downstream separation and processing of target oxidation products. This dissertation focuses on the identification of deleterious oxidation pathways responsible for the formation of undesired products during partial oxidation reactions through utilization of product stability analysis, co-feed reactions, isotopic labeling studies, and probe molecule co-feed reactions conducted in gas-phase batch and flow reactors. We present studies of oxidation pathways in two catalytic systems: acrolein oxidation to acrylic acid over a mixed-metal oxide (promoted MoVOx) catalyst and ethylene epoxidation over a supported metal (promoted Ag/α-Al2O3) catalyst. Results of acrolein oxidation reaction studies performed in a gradientless, recirculating batch reactor are rationalized by a mechanistic reaction network and a kinetic model rationalizing unselective C-C bond scission and formation pathways and show that reactions of both acrolein and acrylic acid generate byproducts. Batch and flow reactor studies of degradation of ethylene oxide show that catalyst metal and support surfaces contribute to its consumption.

Prolonged field care (PFC) for treatment of battlefield and trauma injuries requires the advancement of wound management techniques in order to prevent loss of life or limb prior to hospitalization in austere combat locations where medical evacuation is delayed. The goal of this project is to design a hydrogel wound dressing capable of providing sustained release of antibiotics, analgesics, and hemostatic agents over a three-day period. Poly(ethylene glycol) (PEG) hydrogels were fabricated through crosslinking using redox initiators – ammonium persulfate (APS) and tetramethylethylene diamine (TEMED). Hydrogels were characterized through the mass swelling ratio (qm) to determine the mesh size (ξ) and thus qualitatively predict the release kinetics of the therapeutic drugs. Hydrogels with incorporated therapeutic drug were placed in known volumes of deionized water, from which aliquots were taken at set time intervals. A UV Visible Spectrophotometer determined the aliquots’ absorbance which determined the cumulative release kinetics. Ultimately, three-day sustained release of the therapeutic drugs from the PEG hydrogel was achieved through retarding the diffusion of the therapeutic drugs by incorporating acrylic acid.

We report the kinetics, mechanisms, and site densities of parallel ethanol dehydration and dehydrogenation over gamma-alumina (γ-Al2O3), a high surface area and thermally-stable metal oxide used both as a catalyst support and as a Lewis acid catalyst in industrial practice. We further extend our investigations to diethyl ether conversion over γ-Al2O3 to describe the reaction network for ethanol dehydration and dehydrogenation at conversions exceeding 10%. Steady state measurements demonstrate that unimolecular and bimolecular ethanol dehydration rates are inhibited by water-ethanol co-adsorbed complexes at 488 K. Reactive surface intermediates, rather than co-adsorbed complexes, inhibit the rates of ethanol dehydration and dehydrogenation at industrially-relevant temperatures (>623 K). Co-processing pyridine with ethanol/water feed mixtures results in a reversible inhibition of both unimolecular and bimolecular ethanol conversion pathways; the synthesis rates of ethylene and acetaldehyde are inhibited to a greater extent than diethyl ether synthesis rates, establishing that unimolecular reactions occur on a pool of catalytic sites separate from the pool for bimolecular dehydration reactions. An observed 1:1 ratio of acetaldehyde and ethane in the eluent verifies that ethanol dehydrogenation proceeds via a hydrogen transfer mechanism. We employ asymmetric ethers as probes to establish ether conversion on γ-Al2O3 occurs through a disproportionation pathway to form an olefin and an alcohol, rather than through a hydration pathway. Diethyl ether disproportionation rates were verified to (i) possess an intrinsic rate constant that is within a factor of two of that of unimolecular ethanol dehydration and (ii) be inhibited by pyridine to the same extent as ethylene synthesis rates from ethanol dehydration. These observations are consistent with a proposed mechanism in which ether disproportionation and unimolecular alcohol dehydration occur through a common alkoxide reaction intermediate and on a common pool of catalytic sites. Our combined investigations of alcohol and ether conversion establish the existence of two distinct pools of catalytic centers, verify all unimolecular pathways of alcohol dehydration, dehydrogenation, and ether disproportionation occur on a common set of active sites, and provide a rigorous kinetic description of these pathways.

Abstract: Polymer solutions are characterized based on their viscoelasticity to improve the displacement efficiency for enhanced oil recovery. Contribution of viscoelastic polymers solution’s elasticity on oil recovery needs to be analyzed thoroughly for better screening of polymers for field operations. In this work, the individual effect of the elasticity of polymers (hydrolyzed polyacrylamide) on oil recovery, and residual resistance factor (RRF) was determined for secondary polymer flood oil recovery experiments with varying degree of water saturation. HPAM solutions, having identical shear viscosity but different elasticity, were analyzed. A series of flooding experiments were performed using a cylindrical core (simulating linear flow) sand pack saturated with heavy oil for different blends of HPAM. Results show that although polymer solutions with higher elasticity yield higher oil recovery, but they have high RRF values. Also, if the water saturation is high before polymer flooding, this elasticity behavior is prominent. The injectivity and hydrolysis of HPAM in severe alkaline conditions is a major challenge for oil industry. It is of great importance that injected polymer or micro gels show higher injectivity and alkali resistance behavior without compromising with the amount of oil recovered. To overcome shortfall of conventional HPAM, new crosslinked (cP(AA-st-NVP)) and co (P(AA-co-NVP) polymer were synthesized using Acrylic Acid (AA) and N-vinyl-2-pyrrolidinone (NVP), and N,N’-methylenebisacrylamide as a crosslinking agent by free radical polymerization. These newly synthesized polymers were compared for rheology, heavy oil recovery, injectivity, RRF value with high molecular weight HPAM in alkaline and non-alkaline conditions. Crosslinked polymer and co-polymer showed stable viscoelastic properties in alkaline conditions than conventional HPAM due to intermolecular bonding, though the molecular weight for the later was high. The RF(resistance factor) and RRF for crosslinked polymer were much lower than HPAM, suggesting high injectivity and lower adsorption/retention of the crosslinked and co polymer. The overall recovery of heavy oil using cross linked polymer and copolymer was also ~7% higher than HPAM.

It was demonstrated for the first time that RAFT polymerizations of NIPAAm can be carried out directly in water at room temperature without photo initiator under UV radiation. Under these conditions, the controlled/living features could be proven for a large range of monomer/RAFT agent ratios. Moreover, even at a monomer conversion exceeding 80%, polymerization control (PDI

The precipitation polymerization of acrylic acid in supercritical carbon dioxide (scCO2) was carried out in a continuous stirred tank reactor. The product polymer was a white, dry, fine powder that dissolved in water. A wide range of polymer molecular weights (5 to 200 kg/mol) was obtained. The effect of the operating variables on the polymerization rate and on the polymer molecular weight was evaluated. The polymerization showed distinct deviations from the normal solution polymerization. By assuming that chain initiation occurs in the solution phase, but chain propagation and chain termination occur in the polymer phase, a 'surface polymerization model' and a 'particle polymerization model' both described the polymerization well. Scanning electron micrographs showed that three types of polymer particles were obtained: agglomerates of primary particles of about 100 nanometers in size, irregular particles of 5—20 micrometers, and spheres of 10—100 micrometers. It is speculated that the agglomerates were produced when the polymerization temperature (TP) was below the polymer glass transition temperature (Tg), the irregular particles were obtained when TP was close to Tg, and the spheres were prepared when TP was above Tg. The CO2 absorption into poly(acrylic acid) (PAA) was measured with a quartz crystal microbalance. The Tg depression by scCO2 was calculated with the Chow's equation. The calculated results lent strong support to the proposed particle formation mechanism. Cross-linking polymerization of acrylic acid in scCO2 was studied in a batch reactor at 50°C and 207 bar. All products were white, dry, fine powders. By adjusting the cross-linker concentration, water-soluble and water-insoluble PAAs were synthesized. The water-insoluble PAA was neutralized by ammonia gas and sodium hydroxide alcohol solution to make superabsorbent polymers.