Investigation of Alkyl Ether Carboxylate Surfactants Performance in Carbonate Reservoirs

NO ABSTRAC

Synergistic Surfactant Interactions and the Consequences on Phase Behavior, Interfacial Tension Reduction and Hydrophobic Surface Wetting

The ability for some of the nonionic trisiloxane surfactants to completely and rapidly wet a hydrophobic surface has been well documented for several years. However, to date, the behavior of the trisiloxane surfactants at the solid-liquid interface is not yet completely understood, leading to an incomplete understanding of the mechanism for complete wetting. In this work we report our findings with regard to the synergistic interactions between polyethylene oxide surfactants of the general structure CiE j and compare the behavior to a known super wetting surfactant. Pendant drop tensiometry experiments and sessile drop contact angle measurements on hydrophobic surfaces were conducted on combinations of CiE j surfactants with 1-dodecanol. We found that a number of combinations were capable of reducing significantly the air-liquid tension, however only systems that exhibited the propensity to form extended liquid crystalline phases, as shown by the combination of cross-polarized microscopy, cryo-TEM, and light scattering experiments, were able to improve on the wetting performance of the these systems. We have also conducted the parallel experiment focused on the surfactant adsorption at the hydrophobic solid-liquid interface. Using in-situ infrared internal reflection spectroscopy and complimentary sum-frequency generation spectroscopy, we are able to dynamically interrogate the surfactant adsorption kinetics and interfacial water structure evolution at the hydrophobic solid-liquid interface. We will relate these findings to gain insight into the molecular requirements for superspreading

THERMAL STABILITY STUDY OF AQUEOUS OXTOCIN FORMULATION FOR INTRANASAL DELIVERY

Master'sMASTER OF ENGINEERIN

Amphiphiles Self-Assembly: Basic Concepts and Future Perspectives of Supramolecular Approaches

Amphiphiles are synthetic or natural molecules with the ability to self-assemble into a wide variety of structures including micelles, vesicles, nanotubes, nanofibers, and lamellae. Self-assembly processes of amphiphiles have been widely used to mimic biological systems, such as assembly of lipids and proteins, while their integrated actions allow the performance of highly specific cellular functions which has paved a way for bottom-up bionanotechnology. While amphiphiles self-assembly has attracted considerable attention for decades due to their extensive applications in material science, drug and gene delivery, recent developments in nanoscience stimulated the combination of the simple approaches of amphiphile assembly with the advanced concept of supramolecular self-assembly for the development of more complex, hierarchical nanostructures. Introduction of stimulus responsive supramolecular amphiphile assembly-disassembly processes provides particularly novel approaches for impacting bionanotechnology applications. Leading examples of these novel self-assembly processes can be found, in fact, in biosystems where assemblies of different amphiphilic macrocomponents and their integrated actions allow the performance of highly specific biological functions. In this perspective, we summarize in this tutorial review the basic concept and recent research on self-assembly of traditional amphiphilic molecules (such as surfactants, amphiphile-like polymers, or lipids) and more recent concepts of supramolecular amphiphiles assembly which have become increasingly important in emerging nanotechnology

Prediction of partition coefficients for systems of micelles using DFT

Programa de Doctorat en Química Teòrica i Modelització Computacional[eng] A compound’s solvent−water partition coefficient (log P) measures the equilibrium ratio of the compound’s concentrations in a two-phase system: as two solvents in contact or a system of micelles in an aqueous solution. In this thesis, the partition coefficient of three groups of small compounds (alcohol, ether, and hydrocarbons) in 10 different solvents (benzene, cyclohexane, hexane, n-Octane, toluene, carbon tetrachloride, heptane, trichloroethane, and octanol) was computed used DFT and B3LYP method with 6.31G(d), 6.311+G** and 6.311++G** basis sets. It is obtained that the partition coefficient of alcohol solutes in various solvents using the 6.31G(d) basis set indicates a satisfactory correlation with experimental values. The correlation between the experimental value and the partition coefficient of ether solutes in different solvents using the 6.311++G** basis set shows high agreement. The experimental data displayed a high correlation with the partition coefficient computed for hydrocarbon compounds in various solvents using all three basis sets: 6.31G(d), 6.311+G**, and 6.311++G**. In addition, we have studied the correlation of the experimental partition coefficients in Sodium Dodecyl Sulfate (SDS), Hexadecyltrimethylammonium bromide (HTAB), Sodium cholate (SC), and Lithium perfluoro octane sulfonate (LPFOS) micelles with ab initio calculated partition coefficients in 15 different organic solvents. Specifically, the partition coefficients of a series of 63 molecules in an aqueous system of SDS, SC, HTAB, and LPFOS micelles are correlated with the partition coefficient in heptane/water, cyclohexane/water, n-dodecane/water, pyridine/water, acetic acid/water, octanol/water, acetone/water, 1-propanol/water, 2-propanol/water, methanol/water, formic acid/water, diethyl sulfide/water, decan-1-ol/water, 1-2 ethane diol/water and dimethyl sulfoxide/water systems. All calculations were performed using the Gaussian 16 Quantum Chemistry package. Molecular structures were generated in the more extended conformation using Avogadro, and geometries of all molecules were optimized using Density Functional Theory (DFT) B3LYP and MO6-2X with 6-31++G** basis set by the continuum solvation model based on density (SMD). The obtained results show that calculated partition coefficients in the alcohol/water mixture give the best correlation to predict the experimental partition coefficients in SDS, SC, and LPFOS micelles. With respect to HTAB micelle systems, a new selection of molecules is created, excluding those containing N atoms and Urea atom groups. Interestingly, the partition coefficient of these chosen molecules exhibits a strong correlation with the experimental partition coefficient. Finally, the partition coefficient of flexible molecules was studied by the same protocol for two solvent combinations, octanol/water and cyclohexane/water. The calculated values were compared with the experimental partition coefficients. The average partition coefficient in octanol solvent exhibited a high correlation with the experimental data. However, for the 16 compounds in the cyclohexane solvent, their partition coefficients do not exhibit significant agreement with the experimental partition coefficients.[cat] S'ha desenvolupat una metodologia computacional per calcular el coeficient de partició de diferents tipus de molècules en sistemes micel·lars. En primer lloc, s'ha calculat el coeficient de partició de tres grups de compostos (alcohol, èter i hidrocarburs) utilitzant el mètode DFT amb el funcional B3LYP. S'han obtingut correlacions satisfactòries amb els valors experimentals. En aquesta tesi s'ha desenvolupat un procediment per calcular els coeficients de partició experimentals en micel·les de dodecilsulfat de sodi (SDS), bromur d'hexadeciltrimetilamoni (HTAB), colat de sodi (SC) i perfluorooctanosulfonat de liti (LPFOS). Específicament, els coeficients de partició d'una sèrie de 63 molècules en un sistema aquós de micel·les de SDS, SC, HTAB i LPFOS es correlacionen amb el coeficient de partició en deu barreges aquoses. Els resultats obtinguts mostren que els coeficients de partició calculats a la barreja alcohol/aigua donen la millor correlació per predir els coeficients de partició experimentals en micel·les SDS, SC i LPFOS. Pel que fa als sistemes micelars HTAB, es crea una nova selecció de molècules, excloent-ne aquelles que contenen àtoms de N aromàtics i grups d'urea. És interessant notar que el coeficient de partició d'aquestes molècules triades mostra una forta correlació amb el coeficient de partició experimental. Finalment, es va estudiar el coeficient de partició de molècules flexibles mitjançant el mateix protocol per a dues combinacions de dissolvents, octanol/aigua i ciclohexà/aigua. Els valors calculats es van comparar amb els coeficients de partició experimentals. El coeficient de partició mitjana en dissolvent octanol va mostrar una alta correlació amb les dades experimentals. Tot i això, per als 16 compostos en el dissolvent ciclohexà, els seus coeficients de partició no mostren una concordança significativa amb els coeficients de partició experimental

Greener Surface Active Reagents: Structure, Property and Performance Relationships

Surfactants are used in many industrial applications, such as flotation, flocculation, water treatment, enhanced oil recovery, emulsification, drug delivery, personal care, detergency, chemical mechanical polishing, etc. The design, development, and characterization of greener surfactants in their applications are required to meet the increasing requirements for environmental protection and an escalating demand from the society for sustainable development. It is a challenge currently to develop structure-property-performance relationships for surfactant mixtures containing greener reagents to obtain maximum efficiency with minimum environmental damages. Even though conventional surfactants and their mixtures are well studied, the fundamental studies of the structure, property and performance relationships for greener surfactants when used individually or in combination with others are just started as more and more attentions are focusing on this area. In this work, solution behaviors of surfactant systems containing several amino acid based greener surfactants have been systematically investigated using various techniques, including surface tensiometry, fluorescence spectroscopy, analytical ultracentrifugation, viscometry and computer simulation to obtain information of the structures of the aggregates formed by greener surfactants or their mixtures with conventional ones in solutions. This comprehensive study helps to elucidate the mechanism of micellization behaviors of the greener surfactant mixtures and understand the roles of molecular structures and interactions in determination of system properties and performance. The colloidal and interfacial properties of a series of lipopeptides synthesized by chemo-enzymatic reactions were studied. They were found very surface active, especially C12/oligo(L-Glu). The effects of chain length of hydrophobic moiety, composition of oligopeptide as well as aqueous chemical conditions, such as pH, on the interfacial properties of the lipopeptides were studied. Results showed the mechanism of how the interfacial and colloidal properties of amino acid based surfactants can be fine tuned by adjusting structures of the molecules. Two new surfactants, Surfactin and FA-Glu, synthesized by genetically engineered bacteria were also evaluated. Both of them showed exceptional surface activity. Genetic engineering also showed its advantages when it was found that Surfactin was limited by its solubility. Quick modifications were made in the bacteria and better option FA-Glu was produced with improved structure for better solubility. The results provide fundamental knowledge of those greener surfactants on their structure-property relationships. A number of amino acid based greener surfactants with systematic structural variations, including sodium lauroyl glutamate (C12Glu), sodium lauroyl alaninate (C12Ala), sodium lauroyl sarcosinate (C12Sar), and sodium lauroyl glycinate (C12Gly), were tested as triblend mixtures with dodecyl glucoside (C12G1) and lauramidoproply betaine (LAPB) to evaluate their performance as a function of their molecular structures. The C12Gly/C13G1/LAPB system was confirmed to have very high viscosity compared to the other systems. It was found the following micellar evolution processes happened in this system that delivered the high viscosity: small spherical micelles evolved into elongated rod-like micelles in the low concentration range, and networks of worm-like micelles formed in the high concentration range. The unique properties achieved by this system were attributed to the packing of the surfactant molecules in the system. Further results confirmed that C12Gly has a desired structure with a packing parameter of 0.4 which favors formation of worm-like micelles. Foaming performance of the selected greener surfactant was also evaluated to compare with commercial benchmark system. Even though sodium dodecyl glycinate itself is not a good foaming agent as the petroleum based non-green surfactant sodium lauryl ether sulfate, when it is mixed with the other two ingredients, significant improvement can be achieved for both foamability and foam stability due to strong synergistic interactions among them. The mixture of sodium dodecyl glycinate, dodecyl glucoside and lauramidopropyl betaine actually can deliver equal viscosity, foamability and foam stability as the benchmark system, which makes this system a leading option for the future formulations in personal care industry. Computer simulation as a powerful tool was used to understand the mechanism how greener surfactant molecules interacted with each other and how they aggregated into micelles from molecular level. Simulation found that when different surfactant molecules were mixed together, the synergistic interaction reduced the electrostatic repulsion between molecules, which led to reduction of the effective space occupied by head groups making the two head groups overlapping on each other partially. The overlapping led to a close packing of molecules. The results suggest that geometry of molecules and the interactions among them play equally important roles in determining the packing of surfactants and in turn the packing controls properties and performance of the whole system. Thus a new formula for effective packing parameter of surfactant mixtures was proposed, in which not only the geometries of molecules but also the interactions among them were included to calculate the effective packing parameter for surfactant mixtures for better predictions of the properties and performance of surfactant mixture systems. The fundamental and systematical work accomplished through this work will have a profound impact on the understanding of greener surfactant mixture systems, as structure, property and performance relationships developed herein will in turn direct the use of greener surfactants in future applications for efficiency and low chemical footprin

Prediction of partition coefficients for systems of micelles using DFT

[eng] A compound’s solvent−water partition coefficient (log P) measures the equilibrium ratio of the compound’s concentrations in a two-phase system: as two solvents in contact or a system of micelles in an aqueous solution. In this thesis, the partition coefficient of three groups of small compounds (alcohol, ether, and hydrocarbons) in 10 different solvents (benzene, cyclohexane, hexane, n-Octane, toluene, carbon tetrachloride, heptane, trichloroethane, and octanol) was computed used DFT and B3LYP method with 6.31G(d), 6.311+G** and 6.311++G** basis sets. It is obtained that the partition coefficient of alcohol solutes in various solvents using the 6.31G(d) basis set indicates a satisfactory correlation with experimental values. The correlation between the experimental value and the partition coefficient of ether solutes in different solvents using the 6.311++G** basis set shows high agreement. The experimental data displayed a high correlation with the partition coefficient computed for hydrocarbon compounds in various solvents using all three basis sets: 6.31G(d), 6.311+G**, and 6.311++G**. In addition, we have studied the correlation of the experimental partition coefficients in Sodium Dodecyl Sulfate (SDS), Hexadecyltrimethylammonium bromide (HTAB), Sodium cholate (SC), and Lithium perfluoro octane sulfonate (LPFOS) micelles with ab initio calculated partition coefficients in 15 different organic solvents. Specifically, the partition coefficients of a series of 63 molecules in an aqueous system of SDS, SC, HTAB, and LPFOS micelles are correlated with the partition coefficient in heptane/water, cyclohexane/water, n-dodecane/water, pyridine/water, acetic acid/water, octanol/water, acetone/water, 1-propanol/water, 2-propanol/water, methanol/water, formic acid/water, diethyl sulfide/water, decan-1-ol/water, 1-2 ethane diol/water and dimethyl sulfoxide/water systems. All calculations were performed using the Gaussian 16 Quantum Chemistry package. Molecular structures were generated in the more extended conformation using Avogadro, and geometries of all molecules were optimized using Density Functional Theory (DFT) B3LYP and MO6-2X with 6-31++G** basis set by the continuum solvation model based on density (SMD). The obtained results show that calculated partition coefficients in the alcohol/water mixture give the best correlation to predict the experimental partition coefficients in SDS, SC, and LPFOS micelles. With respect to HTAB micelle systems, a new selection of molecules is created, excluding those containing N atoms and Urea atom groups. Interestingly, the partition coefficient of these chosen molecules exhibits a strong correlation with the experimental partition coefficient. Finally, the partition coefficient of flexible molecules was studied by the same protocol for two solvent combinations, octanol/water and cyclohexane/water. The calculated values were compared with the experimental partition coefficients. The average partition coefficient in octanol solvent exhibited a high correlation with the experimental data. However, for the 16 compounds in the cyclohexane solvent, their partition coefficients do not exhibit significant agreement with the experimental partition coefficients.[cat] S'ha desenvolupat una metodologia computacional per calcular el coeficient de partició de diferents tipus de molècules en sistemes micel·lars. En primer lloc, s'ha calculat el coeficient de partició de tres grups de compostos (alcohol, èter i hidrocarburs) utilitzant el mètode DFT amb el funcional B3LYP. S'han obtingut correlacions satisfactòries amb els valors experimentals. En aquesta tesi s'ha desenvolupat un procediment per calcular els coeficients de partició experimentals en micel·les de dodecilsulfat de sodi (SDS), bromur d'hexadeciltrimetilamoni (HTAB), colat de sodi (SC) i perfluorooctanosulfonat de liti (LPFOS). Específicament, els coeficients de partició d'una sèrie de 63 molècules en un sistema aquós de micel·les de SDS, SC, HTAB i LPFOS es correlacionen amb el coeficient de partició en deu barreges aquoses. Els resultats obtinguts mostren que els coeficients de partició calculats a la barreja alcohol/aigua donen la millor correlació per predir els coeficients de partició experimentals en micel·les SDS, SC i LPFOS. Pel que fa als sistemes micelars HTAB, es crea una nova selecció de molècules, excloent-ne aquelles que contenen àtoms de N aromàtics i grups d'urea. És interessant notar que el coeficient de partició d'aquestes molècules triades mostra una forta correlació amb el coeficient de partició experimental. Finalment, es va estudiar el coeficient de partició de molècules flexibles mitjançant el mateix protocol per a dues combinacions de dissolvents, octanol/aigua i ciclohexà/aigua. Els valors calculats es van comparar amb els coeficients de partició experimentals. El coeficient de partició mitjana en dissolvent octanol va mostrar una alta correlació amb les dades experimentals. Tot i això, per als 16 compostos en el dissolvent ciclohexà, els seus coeficients de partició no mostren una concordança significativa amb els coeficients de partició experimental

Synthetic fabrication of nanoscale MoS₂-based transition metal sulfides

2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe