MS, University of Cincinnati, 2018, Engineering and Applied Science: Mechanical Engineering

Comparative study of interfacial properties and pool boiling of water along with three surfactant additives is conducted. Each are selected from one charge group; anionic SDS, cationic CTAB and zwitterionic FS-50. Experiments are first conducted to determine interfacial properties such as dynamic and equilibrium surface tension of the surfactant solutions and the contact angle or wettability at the liquid-solid interface. Critical micelle concentration (CMC) of three surfactant samples SDS, CTAB and FS-50 is determined from their respective equilibrium gas liquid interfacial isotherm with varying concentration. Dynamic surface tension for three surfactant solutions at CMC are measured and are fitted using prediction model obtained by Hua and Rosen. Due to difference in molecular weight, ionic group, nature and characteristics of these three surfactants there are distinct differences in their dynamic surface tension characteristics. The data shows time range of variation of surface tension of SDS from 10^-7 to 1 seconds at CMC. Likewise, variation in surface tension of CTAB at CMC is in order of 10^-3 to 1 second. For FS-50 on the other hand, there is a sharp change in surface tension value in short time span in order of 10^-1 to 10 seconds. Static contact angle measurement is done for varying concentration to determine wettability for these three surfactant solutions by sessile drop method. Contact angle first decreased sharply with increase in concentration and became almost constant. FS-50 was found to be highly surface wetting while CTAB had lowest wettability among three surfactant samples. Saturated nucleate pool boiling experiment is conducted for de-ionized, distilled water in a horizontal cylindrical heater at atmospheric pressure to develop boiling curve (q" vs ?T). The process is repeated several times to verify repeatability of data for the boiling experiment. The boiling curve for water is determined which is used as a basis to characterize heat tran (open full item for complete abstract)

Committee: Raj Manglik Ph.D. (Committee Chair); Je-Hyeong Bahk Ph.D. (Committee Member); Milind Jog Ph.D. (Committee Member) Subjects: Engineering

Master of Science, The Ohio State University, 2010, Chemistry

The ability of the lungs to function normally can be rooted back to its physiological and molecular components. The natural lung surfactants that lines the alveolar walls reduce the surface tension in the alveoli, prevent the collapse of alveolar walls and maintain a large surface area for an easy access of oxygen into the bloodstream. The absence of lung surfactants results in the collapse of the alveoli and eventually causes the lungs to become stiff. This situation impairs the easy exchange of gases to and from the bloodstream and causes life threatening diseases. Different replacement lung surfactants (RLS) are currently used worldwide to supplement the lack of natural lung surfactants, especially in premature babies. RLS vary in their formulations and can be derived from animal or synthetic sources. The results presented in this work demonstrate the behavior of the different lung surfactant model systems on water and physiological buffer subphase acquired through surface pressure-area isotherm and Brewster angle microscopy. Shifting of the surface-pressure area isotherms of all lung surfactant model systems towards higher mean molecular areas when spread on the buffer subphase was observed. Various theories explain such shifting and are explored in this thesis. Furthermore, the fluidizing effect of POPG and condensing effect of PA in their binary and ternary mixtures were observed and reported. Also, the effect of KL4 (a 21 amino acid peptide that is believed to mimic the structure of the surface protein SP-B in natural lung surfactants) in the ternary mixture of DPPC-POPG-PA spread on the buffer subphase was explored and observed to play a part in the formation of more condensed phase in the system.

Committee: Heather Allen PhD (Advisor); Susan Olesik PhD (Committee Member) Subjects: Chemistry

Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Molecular dynamics simulations and enhanced sampling techniques were employed to investigate adsorption behavior of surfactants at aqueous (metal-water and oil-water) interfaces. Key findings include: (a) Surfactants exhibit a strong affinity for metallic nanoparticles (MNPs), with a tendency of the alkyl tails to wrap around the MNPs. (b) The polar head of surfactants preferentially adsorbs onto the low-coordinated sites on MNPs, while the surfactant tails show no significant preference to adsorb on different MNP facets. (c) Surfactants with longer tails have a higher tendency to aggregate with themselves upon adsorption onto MNPs. (d) On a partially surfactant-covered planar metal-water interfaces, surfactant micelles preferentially adsorb onto bare metal patches. In contrast, on a fully surfactant-covered metal surface, adsorption is primarily driven by hydrophobic interactions, leading to the formation of a hemispherical configuration. (e) Surfactant micelles encounter a free energy barrier to adsorption on metal surfaces, regardless of the extent of surface coverage. (f) At oil-water interfaces with linear oil molecules, surfactants aggregate at the interface along with the oil molecules that align parallel to the orientation of the surfactants' alkyl tail. (g) In the presence of aromatic oil, linear surfactants and linear oils do not form a structured interface layer. (h) The interfacial tension at the oil-water interface decreases with increasing surfactant concentration.

Committee: Sumit Sharma (Advisor) Subjects: Chemical Engineering; Engineering

Doctor of Philosophy (PhD), Wright State University, 2024, Biomedical Sciences PhD

The deployment of military personnel to austere environments poses significant pulmonary health risks from inhalation of particulates including sand, dust, pollution, and heavy machinery exhaust. When particles are less than 10 µm in diameter, they can penetrate deep within the alveoli and embed within the protective lung surfactant monolayer. Here, absorption of surfactant lipids to the particle surface disrupts the essential monolayer configuration needed to reduce surface tension and prevent atelectasis, thus leading to disease. Currently, there are no in vitro surfactant-producing lung cell models capable of studying the effects of inhaled particles on the human pulmonary surfactant system. A549 cells are the most widely used surfactant-producing cells; however, the surfactant is not well characterized, leaving significant gaps in our current understanding. We hypothesize that surfactant produced by A549 cells grown long-term at an air-liquid interface (ALI) will closely mimic that of human surfactant. In addition, we suspect that diesel particulate exposure will result in physiochemical changes in the surfactant that contribute to the development and progression of disease. To explore this, we grew A549 cells long-term at an air-liquid interface establishing a timeline of surfactant production, secretion, and accumulation over time. We discovered a significant increase in surfactant production on day 14 and the presence of a surfactant layer on day 17, suggesting exocytosis into the hypophase at the apical membrane. Investigation of this surfactant layer revealed a diverse pool of lipids that could be used to investigate suspected pulmonary toxicants. However, the composition was noticeably different than that of native human surfactants. Furthermore, we exposed the current model to diesel particulate to study the mechanism driving the molecular interaction between inhaled particles and pulmonary surfactant. Using untargeted lipidomics, we showed a dose-depende (open full item for complete abstract)

Committee: Saber Hussain Ph.D. (Committee Chair); Michael Raymer Ph.D. (Committee Member); Ulas Sunar Ph.D. (Committee Member); Jayme Coyle Ph.D. (Other); Jeffery Gearhart Ph.D. (Committee Member); David Cool Ph.D. (Committee Member); Christie Sayes Ph.D. (Other); Mike Kemp Ph.D. (Committee Member) Subjects: Biomedical Research; Molecular Biology; Toxicology

Doctor of Philosophy, University of Akron, 2024, Polymer Engineering

In this research, several separation problems were investigated with the aid of porous gel and aerogel media. Oil-water emulsion separation is relevant for several industrial processes such as filtration of automotive engine fuel, crude oil recovery processes, water purification, etc. The difficulty in separation of oil-water emulsions is attributed to the presence of surface active molecules, such as surfactants that stabilize the dispersed phase droplets. The first part of this work focused on the development of novel polymer-based filter media offering high specific surface area and coexisting meso- and macropores in the form of polymer aerogels and their applications in separation of oil-water emulsions. The central hypothesis was the ability of nanoscale polymer strands in the aerogel to adsorb large quantities of surfactant molecules thus depleting water-oil interfaces, destabilizing the emulsion, and promoting coalescence of the droplets. The first two projects investigated the surfactant adsorption abilities of different surface energy polymer gels. It was found that the surfactant adsorption and in turn, the emulsion separation performance of the gels were greatly influenced by the polymer gel surface energy, its pore sizes, surfactant size, and the structural organization of the surfactant molecules on the polymer surface. The third project evaluated several mechanisms of separation of surfactant-stabilized emulsified water droplets from diesel fuel using high surface area (50-370 m2/g) and high porosity (>90%) filter media fabricated by combining aerogels and glass fiber mats in a continuous flow system. The final project focused on designing an effective adsorbent media for quick removal of environmentally persistent, bioaccumulative, and noxious contaminant called perfluorooctanoic acid (PFOA) from water. This research advanced the understanding and established the potential of porous polymer gel and aerogel media in addressing two pressing purification (open full item for complete abstract)

Committee: Sadhan Jana (Advisor); Kevin Cavicchi (Committee Chair); George Chase (Committee Member); Toshikazu Miyoshi (Committee Member); Fardin Khabaz (Committee Member) Subjects: Chemical Engineering; Engineering

Master of Science in Chemical Engineering, Cleveland State University, 2023, Washkewicz College of Engineering

Hierarchical and 2D zeolites address the diffusion limitation of conventional zeolites by enhancing diffusion in the mesopores. So far, the surfactant compounds, which successfully produce hierarchical zeolites, have complex molecular structures making the zeolite synthesis expensive and uncompetitive for commercialization, making cost-effective synthesis of hierarchical and 2D zeolite highly desirable. However, the development of effective synthesis protocols relies on a good understanding of the SDA's influence on crystal morphology development, which is largely unknown. Here, we explore inexpensive and readily available compounds via a dual-SDA strategy and use MFI zeolite as the model system for the research. TPAOH served as the primary SDA to promote MFI zeolite formation and several other surfactant molecules served as the secondary SDA to restrict crystal growth along a particular zeolite channel. First, the synthesis using an in-situ growth method was performed and the concentration of the primary SDA was modulated. Another set of zeolite synthesis conditions, arbitrarily chosen, was used to study the synergistic roles between dual-SDA and synthesis conditions on zeolite crystal morphology development. Moreover, we explored dual-SDA zeolite synthesis in a seed-mediated solution, for which the zeolite seeds promote nucleation and is anticipated to overcome the strong growth restriction of the secondary SDAs. The synthesis conditions had no significant effect on the zeolite formation and the secondary SDA plays a key role in the final crystal morphology, which is attributed to how well the secondary SDA can fit into the zeolite channels and restrict the growth along a particular direction. We further investigate the same set of SDAs for another type of zeolitic material, i.e., silicoaluminophosphates (SAPO). This involved mixing multiple amino acids in a precursor solution with seed crystals of SAPO-34 zeolite. leading to different zeolite crystal phases. (open full item for complete abstract)

Committee: Shaowei Yang (Advisor); Metin Uz (Committee Member); Marvin Thrash (Committee Member) Subjects: Chemical Engineering; Chemistry

Master of Science, Miami University, 2023, Chemistry and Biochemistry

Sulfonate surfactants are too polar to be directly determined by gas chromatography (GC) and so derivatization chemistry (sulfonyl chloride formation, silylation and pyrolytic methylation) of these analytes is necessary. Pyrolytic methylation, rarely applied to sulfonates, was chosen due to its simple sample preparation and the derivatization happening in the GC injection port. In this work, application of pyrolytic methylation to sulfonate surfactants was tried, but poor reproducibility was found explaining the limited literature on this topic. Sulfate surfactants can be indirectly detected through GC-MS by its degradation products formed in the injection port. Straight chain alkyl sulfates were analyzed with success based on the expected alcohol product. Sodium laureth sulfate (SLS), an alkyl ethoxylated sulfate and important commercial detergent, has apparently not been previously considered for GC-MS detection. It was found that 1-dodecanol is the primary degradation product of interest. However, dimethyl sulfate and 1-dodecene were investigated as quantitative markers for linearity studies from SLS chromatograms and reproducibility. The method was then applied to a real-world dishwashing liquid sample to qualitatively determine SLS through ion exchange extraction. The presence of the zwitterionic surfactant lauramine oxide in this commercial product was deemed a potential interference through dodecene formation upon GC-MS analysis.

Committee: Neil Danielson (Advisor); Michael Kennedy (Committee Member); David Tierney (Committee Member); Kevin Yehl (Committee Member) Subjects: Chemistry

Master of Science, University of Toledo, 2023, Chemical Engineering

Multilayer plastics (MLPs) have become one of the most common food packaging materials. By combining multiple polymer types with distinct advantageous properties (e.g., water, light, or oxygen barrier properties), they extend the product shelf life while using less material. Yet, MLPs are challenging to recycle because their layers are difficult to separate, and this difficulty now presents a formidable sustainability challenge. To this end, we have developed new tie-layer materials through the complex coacervation (i.e., self-assembly) between the cationic polyelectrolyte, polyallylamine (PAH) and unsaturated, anionic fatty acids (either oleic acid or linoleic acid). Akin to the liquifying effects of double bonds in cis-unsaturated fats, the double bonds in these fatty acid tails imparted the otherwise-flaky PAH/surfactant complex precipitates with either moldable semisolid or liquid (coacervate) properties. These coacervates were prepared in two different solvents (water and ethanol) and were capable of (1) adhering two dissimilar plastic layers, (2) dissociating during recycling, thus enabling facile separation of MLP layers for further processing, and (3) as a bonus, serving as oxygen scavengers. These complexes exhibited tunable rheological properties, which ranged from viscous liquids (when solvated in ethanol) to putty-like semisolids (when formed in water) and coincided with solvent-dependent changes in their microstructure, where replacing water with ethanol led to a disruption of their lamellar order. Moreover, when prepared as low-viscosity dispersions of submicron coacervate droplets suspended in ethanol, these coacervates could be easily spread onto plastic substrates and (on partial drying) formed adhesive films that could bond dissimilar plastic layers, such as polyethylene terephthalate (PET), low-density polyethylene (LDPE), and ethylene vinyl alcohol (EVOH), with fewer defects and higher adhesion strengths than those achieved by spreading macro (open full item for complete abstract)

Committee: Yakov Lapitsky (Committee Chair); Maria Coleman (Committee Member); Joseph Lawrence (Committee Co-Chair) Subjects: Chemical Engineering; Chemistry; Packaging

Doctor of Philosophy, The Ohio State University, 2022, Chemical Engineering

Drag reduction (DR) by additives typically involves the use of either high molecular weight polymer or surfactants, and can reduce turbulent pressure losses in pipes by up to 90%. These additives, particularly high polymers, have seen considerable use in increasing the throughput of crude oil pipelines. Surfactant additives, while even more effective than their polymer cousins, have not seen widespread adoption despite their applicability to recirculating district heating or cooling networks. Due to their effects on the turbulent structure of pipe flow, drag reducing additives also result in the loss of radial mixing, and thus the suppression of convective heat transfer. This is referred to as the 'heat transfer reduction' (HTR) effect. Under normal conditions, drag reducing additives can reduce convective heat transfer in even greater amounts than they do turbulent pressure losses. Much of the recent research in the field of surfactant drag reduction has, therefore, been dedicated to the mitigation of heat transfer reduction. In this work, two projects are presented which successfully achieve this goal. In the first, a constricted heat exchanger is used to locally increase the shear stresses experienced by the working fluid. Simultaneously, a `weak' drag reducing solution comprised of quaternary ammonium salts with saturated tails 16 and 14 carbons in length and the counterion 3-chlorobenzoic acid. In conjunction with the constricted heat exchanger, this mixture is able to simultaneously generate high (>60%) DR and low (>30%) HTR over a range of flow rates and temperatures. Other unique properties of the system are examined, including switchability and hysteresis. The second study involves the design and application of 'gentle' static mixers. Rather than being designed to destroy the micellar structure thought to be responsible for DR, these mixers are intended to periodically disrupt the thermal boundary layer in the heat exchanger, thus improving heat tr (open full item for complete abstract)

Committee: Kurt Koelling (Advisor); Jim Rathman (Committee Member); Stuart Cooper (Committee Member); Andrew Maxson (Committee Member) Subjects: Chemical Engineering; Energy; Engineering; Fluid Dynamics

Doctor of Philosophy (PhD), Ohio University, 2022, Chemical Engineering (Engineering and Technology)

In this work, advanced molecular dynamics simulations were employed to study the adsorption of surfactants at metal-water interfaces. A new sampling methodology was developed in molecular simulations that allows efficient sampling of the most thermodynamically stable adsorbed morphology of adsorbed surfactants. The hydration free energies of surfactants and their micelles were also studied. The major findings of this work are: (a) Both unaggregated surfactants and their micelles strongly adsorb on the bare metal-water interfaces; (b) cationic surfactant micelles experience a free energy barrier to adsorption and adsorb by disintegrating on the surface; (c) hydrophobic interactions between the alkyl tails of surfactants promote adsorption, while the accumulation of charged surfactants on the surface inhibits adsorption. As a result, small alkyl tail (C4) quaternary ammonium surfactants adsorb as a sparse layer. Quaternary ammonium surfactants with longer alkyl tails (C12) adsorb as a hemispherical micelle sitting atop a monolayer of adsorbed molecules lying parallel to the surface. Charge neutral surfactants with long alkyl tails, like decanethiol, adsorb in a high-density morphology with molecules standing up on the surface, and a second layer of molecules lying parallel to the surface. (d) Hydration free energy of alkanes is dictated by the entropic loss of water molecules surrounding the alkanes; (e) addition of a hydroxyl group to the terminal position of the hydrophobic tails of the cationic surfactant molecules helps in reducing their micellization tendency and enhancing their aqueous solubility by two orders of magnitude.

Committee: Sumit Sharma (Advisor); Srdjan Nesic (Committee Member); Horacio Castillo (Committee Member); Katherine Cimatu (Committee Member); David Young (Committee Member) Subjects: Chemical Engineering; Molecular Physics

Doctor of Philosophy, Miami University, 2021, Chemistry and Biochemistry

This work is designed to understand how to efficiently synthesize polymers for and to understand two major biotechnology applications - protein-polymer conjugates, and macromolecular surfactants for favorable cell membrane interactions. Polymers are a ubiquitous class of molecules in the world due to the unique and complex properties that arise from combining simple building blocks in particular combinations. Nature has adopted proteins, amino acid polymers that fulfill myriad critical functions. In recent years, the biotechnology industry has begun to manipulate proteins by attaching synthetic polymers to them, conferring invisibility to the immune system for protein drugs, or enhanced stability, activity, or recyclability to enzymes for biocatalysis. A protein molecule on its own is sufficiently complex to require years-long research projects to fully understand. Thus, protein-polymer conjugates are still poorly understood. In this work, we present a technique for the study of conjugates, enabled by reversible deactivation radical polymerization, which by nuclear magnetic resonance allows for an atomic-level view. We also explored the challenge of attaching two distinct polymers to a single protein molecule in an efficient and well-defined manner, which would enable still more complex conjugates. Lipid membranes and the proteins that reside within them are another area of biotechnology that polymers have broken into. Cell membranes and the proteins within them experience a complex play of intermolecular forces. The unique location of membrane proteins makes them difficult to study, as they are not readily crystallized, and resuspension using traditional detergents can be detrimental to protein structure. Styrene-maleic acid copolymers and their relatives are known to form a belt containing lipids and membrane proteins in disk-shaped nanoparticles. These maintain the bilayer shape and avoid the use of detergents and have enabled characterization of previously (open full item for complete abstract)

Committee: Dominik Konkolewicz PhD (Advisor); Richard Page PhD (Advisor); Richard Taylor PhD (Committee Chair); Carole Dabney-Smith PhD (Committee Member); Jason Berberich PhD (Committee Member) Subjects: Biochemistry; Biophysics; Chemistry; Polymer Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2021, Chemistry

This dissertation will focus on the use of multidimensional mass spectrometry (MS) techniques for the characterization of complex polymeric materials and mixtures, especially of samples that are impossible or difficult to characterize by other analytical methods. The research can be separated into two categories; applying separation techniques and mass spectrometry to polymeric mixtures, and using atmospheric solids analysis probe (ASAP)-MS for the analysis of cross-linked polymeric networks. Poly-glycidyl phenyl ether (PGPE) samples synthesized via zwitterionic ring opening polymerization by the Grayson Research Group (Tulane University) were initially analyzed using matrix assisted laser desorption ionization (MALDI) MS. Although able to confirm the presence of linear products, MALDI-MS was unable to distinguish between the tadpole and cyclic products, both of which are produced by back-biting reactions and are structural isomers. To overcome this problem, ultraperformance reversed-phase liquid chromatography interfaced with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) was employed. These experiments showed that the tadpole isomer elutes before the cyclic structure due to the increased polarity associated with a free hydroxyl end group on the tadpole tail. The achieved separation showed that the ratio of tadpole to cyclic species increases with each repeat unit. These results agree with the synthetic predictions, as the potential for forming tadpole structures by back-biting should increase with increased polymer chain length. Once separated, the two isomers could be independently analyzed by tandem mass spectrometry. The cyclic and tadpole species exhibit unique fragmentation patterns and include structurally diagnostic fragments for each structure. The importance in these peaks lies in their ability to provide information about the tadpole to cyclic ratio, without the need for inline separation techniques prior to MS. Surfactants are co (open full item for complete abstract)

Committee: Chrys Wesdemiotis (Advisor); Claire Tessier (Committee Chair); Adam Smith (Committee Member); Aliaksei Boika (Committee Member); Wang Junpeng (Committee Member) Subjects: Chemistry; Materials Science; Polymer Chemistry; Polymers

PhD, University of Cincinnati, 2021, Pharmacy: Pharmaceutical Sciences

Micellar, microemulsion, and gel systems are frequently used in personal care products to achieve the desired rheological, aesthetic, and cleansing properties. Surfactants are frequently used in these products and self-assemble with non-covalent interactions (e.g. hydrogen bonding, van der Waals forces) to form micellar systems and, when combined with oil and a co-surfactant, microemulsions. Gelators assemble into networks that trap solvent, making them excellent thickeners. Depending on the gelator's molecular structure, the monomers can assemble covalently or, like surfactants, with non-covalent interactions. Systems that self-assemble via non-covalent interactions can be sensitive to various aspects of the formulation, such as the presence of salt, the ratio of solvent to surfactant or gel, and the solvent properties. Systematically studying the effects of various additives on the self-assembly of surfactants and gels is valuable to learn how to effectively tune the properties of these systems to maximize the release of actives and improve product performance. Sodium trideceth-2 sulfate and sodium laureth-1 and -3 sulfate were studied as individual primary surfactants while cocamidopropyl betaine was included as a cosurfactant to create three different mixed-surfactant systems. Dipropylene glycol (DPG, cosolvent) and two perfume mixtures consisting of 3 or 12 perfume raw materials (PRMs), spanning a range of log P values and molecular structures, were added to each mixed-surfactant system to study their effects on the surfactant self-assembly and release of perfumes into the headspace. The effect of dilution with water was also investigated to simulate rinse-off situations. Changes to the self-assemblies of two low-molecular weight gels (LMWGs) were studied as a function of gel concentration, the presence of carbamazepine, and sonication. Small-angle neutron scattering, gas-chromatography mass-spectrometry, nuclear magnetic resonance, microscopy, and statistic (open full item for complete abstract)

Committee: Harshita Kumari (Committee Chair); Kavssery Ananthapadmanabhan (Committee Member); Thomas Beck Ph.D. (Committee Member); Kevin Li Ph.D. (Committee Member); Edward Smith, III (Committee Member) Subjects: Pharmaceuticals

Doctor of Philosophy, The Ohio State University, 2021, Chemistry

Marine aqueous interfaces constitute one of the most prevalent surfaces in the biosphere and the atmosphere, and understanding the physicochemical processes at these interfaces is of significant importance for informing Earth system models. In the following chapters, surfactant organization and morphology on aqueous solutions of high ionic strength are explored as a proxy for the organic films coating sea spray aerosol (SSA) surfaces and the sea surface microlayer (SSML). First, a proxy film mixture comprised of the saturated fatty acids myristic acid (C14), palmitic acid (C16), and stearic acid (C18) was selected to study sea spray aerosol film morphology as a function of atmospheric acidification. The nascent SSA proxy film is fluid and flexible, whereas the acidified film is more rigid; as a result, the nascent SSA proxy film folds upon collapse, and the acidified film fractionates into three-dimensional structures with compression. Next, the influence of surfactant organization on one-dimensional surface-sensitive infrared spectroscopy was examined. Decreasing intermolecular distances between a soluble perfluorooctanoic acid film and an insoluble arachidic acid (C20) monolayer cause vibrational exciton delocalization across the surfactants, manifesting in alkyl and fluoroalkyl signal reduction and deviations from the Beer-Lambert law. The aqueous electrolyte composition in part modulates surfactant intermolecular spacing, affecting the extent of vibrational delocalization. Consequently, quantitative analyses involving alkyl and fluoroalkyl one dimensional vibrational peak intensities must be approached with caution. Lastly, surfactant-mediated cooperative adsorption of a soluble polysaccharide to a proxy sea surface microlayer is studied. Seawater divalent cations facilitate ionic bridges between the marine-relevant, anionic polysaccharide alginate and a partially deprotonated palmitic acid monolayer. Calcium promotes the strongest bridging interactions, and pal (open full item for complete abstract)

Committee: Heather Allen (Advisor); Bern Kohler (Committee Member); Sherwin Singer (Committee Member); Donald Yau (Committee Member) Subjects: Atmospheric Chemistry; Biogeochemistry; Chemistry; Physical Chemistry

Doctor of Philosophy (PhD), Ohio University, 2020, Chemistry and Biochemistry (Arts and Sciences)

Investigating the specific local environment and molecular interactions at liquid surfaces is crucial in comprehending physical, chemical, and biological processes. Probing the interfacial molecular conformations will provide an insight into the relationship between surface structure and the governing interactions at the surface. Herein, this dissertation used the approach of the effect of substituents on the interfacial conformation of a methacrylate backbone, to observe such surface structure interaction relationships. The ethyl end of the methacrylate monomer was substituted with bulky groups and electron-withdrawing groups. These substituted monomers were synthesized via nucleophilic addition elimination reaction and characterized using sum frequency generation (SFG) spectroscopy at the air-liquid interface. The spectroscopic results were correlated with surface tension measurements and the overall dipole moment of the molecules. The presence of bulky substituents affected the orientation distribution of the interfacial molecules. On the other hand, in the presence of electron-withdrawing groups, the intensity of vibrational modes was affected, suggesting the changes in interfacial molecular conformations and existing intermolecular interactions. In another project, quaternary ammonium surfactants were utilized to assess their conformation and orientation at the air-water interface using SFG spectroscopy. Herein, the approach of solvent isotopic substitution was used to investigate the surfactant water interactions. The results showed the addition of deuterated water rearranges its head group parallel to the interface and straightens its chain with reduced gauche defects. The change in the conformation of the surfactant molecules at the air-liquid interface showcased the difference in intermolecular interactions for water and deuterated water. In summary, these studies revealed the importance of SFG spectroscopy as a tool to probe surface structures in gauging m (open full item for complete abstract)

Committee: Katherine Cimatu (Advisor) Subjects: Chemistry; Molecules; Optics; Physical Chemistry; Polymers

Doctor of Philosophy, The Ohio State University, 2019, Environmental Science

Hydraulic fracturing and horizontal drilling technologies have greatly improved the production of oil and natural-gas from previously inaccessible non-permeable rock formations. Fluids comprised of water, chemicals, and proppant (e.g., sand) are injected at high pressures during hydraulic fracturing, and these fluids mix with formation porewaters and return to the surface with the hydrocarbon resource. Despite the addition of biocides during operations and the brine-level salinities of the formation porewaters, microorganisms have been identified in input, flowback (days to weeks after hydraulic fracturing occurs), and produced fluids (months to years after hydraulic fracturing occurs). Microorganisms in the hydraulically fractured system may have deleterious effects on well infrastructure and hydrocarbon recovery efficiency. The reduction of oxidized sulfur compounds (e.g., sulfate, thiosulfate) to sulfide has been associated with both well corrosion and souring of natural-gas, and proliferation of microorganisms during operations may lead to biomass clogging of the newly created fractures in the shale formation culminating in reduced hydrocarbon recovery. Consequently, it is important to elucidate microbial metabolisms in the hydraulically fractured ecosystem. The numerous nitrogen and carbon sources injected in input fluid mixtures may sustain shale-associated microorganisms, prompting a need to investigate the capacity of microbial life to enzymatically transform organic chemicals commonplace to hydraulic fracturing operations. In Chapter 2, we investigated the putative microbial metabolisms of two bacterial genera frequently identified in the first few weeks to months after hydraulic fracturing occurs (Marinobacter and Arcobacter). Using microbial culture-dependent methods (e.g., genomics, salinity range and carbon source growth testing) and microbial culture-independent methods (e.g., metagenomics) coupled to geochemical measurements from four Appalachian (open full item for complete abstract)

Committee: Paula Mouser (Advisor); Gil Bohrer (Advisor); Matthew Sullivan (Committee Member); Ilham El-Monier (Committee Member); Natalie Hull (Committee Member) Subjects: Chemistry; Environmental Engineering; Environmental Science; Microbiology

Master of Science, The Ohio State University, 2017, Chemistry

Surface potential is a valid and relevant macroscopic technique used to determine the orientation of water dipoles at the interface of air and water. In this work, an ionization based surface potential (SP) instrument is designed and configured. The first set of results are presented here. A custom designed americium-gold matrix foil with an activity of 20µCi and 9.5mm surface diameter is used as the air electrode suspended over a sample solution. A parallel aligned platinum gauze electrode is immersed in solution directly under the probe. The electrodes are connected to a Keithley 6517B electrometer. Subsequent measurements are made in the DC voltage mode of the electrometer for charged surfactants (SDS, CTAB) and inorganic electrolytes (NaCl, MgCl2, Na2SO4, MgSO4). The surface potential measurements were compared to studies by Nakahara et. al, (2005, 2008) and Jarvis and Scheiman (1968). The potentials measured for SDS showed linear increase from 1 to 5mM consistent with previous findings in that regime. A similar result is observed with CTAB in the 0.8-1mM concentration regime. The measured sign of the potentials is consistent with the sign of the surface charge for these molecules. For the inorganic salts, the surface potential difference is plotted versus concentration. Though the magnitude of these results does not fall within range of the Jarvis-Scheiman study, similar trends are observed. Positive trends are observed for Na2SO4 and MgSO4 and negative trends for NaCl and MgCl2. These results are compared to several MD simulation studies which show the surface propensity for ions and its effect on the electric double layer. The results of this study are key to validating observations of measurements using macroscopic techniques for air/water interface studies. Knowledge gained from these studies will provide insight into questions regarding multiple aqueous ion studies: atmospheric aerosol chemistry, thundercloud electrification, geochemistry, ocean surface pr (open full item for complete abstract)

Committee: Heather Allen (Advisor); Anne Co (Committee Member) Subjects: Chemistry

Master of Science, University of Akron, 0, Polymer Science

The chemical and physical properties of materials are determined not only by composition but also hierarchical structures. Hierarchical structures are formed by “bottom up” method, self-assembly of nano-scale building blocks into supramolecular assemblies via secondary interactions.1 In recent years, a series of functionalized POSS were utilized as “nanoatoms” to synthesize well-defined giant molecules. As a kind of giant molecules, giant surfactants are focused in my work. To investigate the fundamental principles of self-assembly, the giant surfactants with precise molecular structures have been synthesized by clicking “nanoatoms” to flexible polymer tails with controlled molecular weight. Because the self-assemblies of giant surfactants are sensitive to topological structures, a series of “giant surfactant” with multi-heads or multi-tails have been synthesized.2 In my work, the APOSS based star-shape giant molecules with or without polystyrene (PS) tails were precisely synthesized via “living” radical polymerization and “click chemistry”. The chemical structure of the product was confirmed by 1H NMR spectrum, 13C NMR spectrum, GPC spectra, FT-IR spectra and MALDI-TOF mass spectra. After the self-assembly of samples in solution, the structures formed were investigated by transmission electron microscopy (TEM), static light scattering (SLS) and dynamic light scattering (DLS).

Committee: Stephen Cheng Dr. (Committee Member); Toshikazu Miyoshi Dr. (Advisor) Subjects: Chemical Engineering; Chemistry; Materials Science; Polymer Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2016, Chemical Engineering

Several studies have been published describing the corrosion inhibition effectiveness of surfactant admixtures by measuring the ability of surfactant molecules to physically adsorb onto metal surfaces. However, the effects of these admixtures have not been previously studied on coated metal surfaces to determine their corrosion inhibition mechanism. While corrosion protective coatings isolate exposed metal surfaces by forming a barrier between a substrate and the electrolyte, their performance is highly dependent on their interaction with their immediate environment. During the winter season in Snowbelt areas where chloride roadway deicers are greatly employed, coated metal surfaces in vehicles are constantly exposed to harsh and changing environments making them susceptible to failure. In order to extend the service life of these exposed coated surfaces, additional treatment by surfactant admixtures is regarded as an effective corrosion prevention strategy. In this work, the corrosion mechanism of surfactant admixtures on coated metal panels is evaluated by understanding the interaction of the liquid-solid interface. Despite the numerous mechanisms of inhibition behavior, it is hypothesized in this study that the contributions from inhibition solution systems create a protective layer over substrates by the formation of multi layers from aggregation or adsorption of surfactants. Furthermore, this study will help understand the relationship of the surface of corrosion protective coatings and the interaction with its environment. Electrochemical impedance spectroscopy (EIS) is applied to evaluate the corrosion performance of a high performance, low VOC, two component polyurethane enamel and a high performance UV-cured coating system on carbon steel alloy A36 under immersion testing of sodium chloride solutions of surfactant admixtures. This electrochemical technique permits the evaluation of the properties of the coating system by monitoring its degradation (open full item for complete abstract)

Committee: Chelsea Monty Dr. (Advisor); Scott Lillard Dr. (Committee Member); Gang Cheng Dr. (Committee Member); Christopher Miller Dr. (Committee Member); John Senko Dr. (Committee Member) Subjects: Automotive Materials; Chemical Engineering; Engineering; Materials Science; Physical Chemistry

Master of Science, University of Akron, 2016, Polymer Science

Fluoro-functional materials are widely used because of their superior omniphobic properties. These properties mean that those materials are not only hydrophobic but also oleophobic. Their low surface free energy make these properties outstanding and useful. For example, fluorous materials have many applications in developing self-cleaning materials and anti-fogging films, etc. In this article, a typical way was used to synthesize some novel asymmetric giant surfactants, and the self-assembly behaviors of them were investigated in the bulk. Atomic transfer radical polymerization (ATRP) and sequential “click” approach were chosen to design and synthesize FPOSS-PSn samples which are one polyhedral oligomeric silsesquioxane cage with seven fluorinated alkyl chain and different molecular weights of polystyrene (PS). And their self-assembly behaviors in the bulk were found that they could form a lot of different ordered structures, such as lamellae, perforated layer, and cylinders. The general thing is that the functional groups on the POSS cages can affect the interaction parameters of different POSS cages with the PS chain. Then the POSS cages will separate from the PS domains to form a new phase. However, the FPOSS cages are likely to crystallize in the lamellae phase which will make further phase separation of the POSS cage from fluorous alkyl chain outside. These results will help us design and synthesize some interesting and useful self-assembling materials based on POSS-polymer with desired physical properties.

Committee: Stephen Z.D. Cheng (Advisor) Subjects: Chemistry; Materials Science; Polymer Chemistry; Polymers