MFA, Kent State University, 2018, College of Communication and Information / School of Visual Communication Design

The purpose of this investigation is to examine how standardized graphic design labeling of artificial food additives informs and influences the consumer in their purchasing choices. By law, standard nutrition labeling such as the Ingredient List must appear on prepackaged food. Consumers utilize this labeling to make purchase decisions when shopping. However, there is confusion over current labeling and, by extension, over additive ingredients presence, purpose, and safety in our food. Consumers pay attention to the nutrients they want to avoid and are voicing growing concerns over the use of additives in our food. Highlighting the presence of all artificial additive ingredients in food labeling design would be utilized by consumers and influence them when shopping. Through qualitative and quantitative design research methods which included a literary review, ethnographic observation, an online survey, and a focus group, it was determined that consumers have an overwhelmingly negative opinion of artificial additives. Participants alleged that manufacturers were trying to deceive the consumer by trying to “hide” ingredients. However, as much as there was distrust of the manufacturer, primary data showed that consumers trusted the standardized format of the labeling because the law requires it. The presence of an authoritative body and the standardization of this information separated it from promotional or marketing efforts. From this evidence, the conclusion is that standardizing the labeling of artificial additives would be trustworthy and, therefore, believable to the consumer. Lack of clarity on food labels can widen the gap between understanding and confusion. All ingredients must be listed using their common and usual names in the Ingredient List. However, research showed that the common and usual name of an ingredient might not always be intuitive or descriptive enough for the consumer. Other regulations, such as listing the function of a chemical prese (open full item for complete abstract)

Committee: Sanda Katila MFA (Advisor); Jessica Barness MFA (Committee Member); Jillian Coorey MFA (Committee Member); Ken Visocky O'Grady MFA (Committee Member) Subjects: Aesthetics; Communication; Design; Marketing

Doctor of Philosophy, Case Western Reserve University, 2014, Chemical Engineering

All semiconductor devices incorporate metallic interconnects, which provide the electrical network within the device. The interconnects are fabricated by electroplating copper from electrolytes containing special additives, enabling bottom-up fill of the vias and trenches. The study herein focuses on identifying new additives screening techniques and characterizing the associated process parameters through systematic experimental investigation and analytical modeling. A new improved test for characterizing the efficacy of the additives system has been developed and validated as a replacement for the classical injection technique. Results of the test have been implemented in a quantitative model indicating the expected gap-fill in wafer plating of small features. Additionally, a computer-based model of the additives co-injection test has been developed. This model accounts for the flow field external to the features and characterizes the actual wafer plating process more precisely than previous models. Fitting experimental data to the model provides more accurate estimates of process parameters, including additive adsorption rates, than heretofore possible. Several process parameters were characterized. Temperature was found to affect additives (polyethylene glycol [PEG] serving as a suppressor and bis(3-sulfopropyl) disulfide [SPS] serving as anti-suppressor) activity. An optimal process temperature of ~30oC was identified, where the SPS depolarized electrode reverts to pure copper plating kinetics and maximal polarization is achieved. The effects of pH, in the range 0.5-2, on the deposition kinetics were found to be minor; however, corresponding effects on seed stability were substantial, with improved seed stability at the higher pH. Substituting chloride with bromide provided slight improvement in the deposition kinetics. With bromide, displacement of the suppressor by the anti-suppressor was slow compared to displacement in the presence of chlori (open full item for complete abstract)

Committee: Uziel Landau (Advisor); Rohan Akolkar (Committee Member); Heidi Martin (Committee Member); Daniel Scherson (Committee Member); Robert Preisser (Committee Member) Subjects: Chemical Engineering

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

The increased use of solar energy for power is anticipated to lead to the shift from traditional power sources to renewable energy sources. Photovoltaic (PV) is a promising technology due to its ability to directly convert sunlight into electricity with no pollution. Solar cells, specifically those based on metal halide perovskites (MHPs) have gained popularity recently due to their power conversion efficiency (PCE) that have increased dramatically over the past 15 years, from 3.8% to more than 26 %. The rapid development in PCE is due to the advanced features that MHPs have such as cost-effective and easy processing, high absorption coefficient, large diffusion length, and low exciton binding energy. In particular, the purpose of this study is to develop solution-processed perovskite solar cells (PSCs) by tuning film morphology and optoelectronic properties of metal halide perovskites incorporated with processing additives, thereby optimizing the performance of PSCs. To maximize the potential of perovskite, controllable crystallization is crucial for producing high-quality perovskite thin films with fewer structural defects and additive engineering is a facile and effective method among other techniques. We mainly investigated the effects of various processing additives on the MHPs based on MAPbI3 perovskite (where MA is CH3NH3) and correlate PCE in term of film morphology, crystallinity, photocurrent hysteresis, optoelectronic properties, device performance and stability of PSCs.

Committee: Xiong Gong (Advisor); Fardin Khabaz (Committee Chair); Mark D. Soucek (Committee Member); Mesfin Tsige (Committee Member); Jie Zheng (Committee Member) Subjects: Energy; Engineering; Materials Science; Nanotechnology

Master of Science (M.S.), University of Dayton, 2022, Chemical Engineering

Nanoparticle additives increase the thermal conductivity of conventional heat transfer fluids like water at low concentrations, which could lead to improved heat transfer fluids and processes. In this study, lignin-based Fe₃O₄ nanoparticles (lignin@Fe₃O₄ ) are investigated as a novel bio-based magnetic nanoparticle additive to enhance the thermal conductivity of aqueous-based fluids. Kraft lignin was used to encapsulate the Fe₃O₄ nanoparticles to increase the dispersion rate and prevent agglomeration and oxidation of the magnetic nanoparticles. Lignin@Fe₃O₄ nanoparticles were prepared using a co-precipitation method and characterized by various experimental techniques, including Transmission Electron Microscopy (TEM) and Vibrating Sampling Magnetometry (VSM). Once fully characterized, lignin@Fe₃O₄ nanoparticles were dispersed in aqueous 0.1 % w/v agar-water solutions at five low concentrations: 0.001 %w/v, 0.002 %w/v, 0.003 %w/v,0.004 %w/v and 0.005 %w/v. Thermal conductivity was measured using METER Group's KD-3 Tempos and the transient line heat source method was used at five different temperature conditions: 25 °C, 30 °C, 35 °C, 40 °C, and 45 °C. Additionally, at room temperature, the thermal conductivity of aqueous-based lignin@Fe₃O₄ suspensions was characterized at the following magnetic fields of 0 Gauss, 100 Gauss, 200 Gauss, 300 Gauss, and 400 Gauss. This study shows an increment of thermal conductivity by about 10% in the highest concentrations and temperature conditions. Additionally, the study also demonstrated the increment of thermal conductivity up to 5% in 200 Gauss magnetic field strength in the highest concentrations at a constant room temperature of 21 °C. This work establishes that lignin-based Fe₃O₄ nanosuspension increases the thermal conductivity of aqueous-based fluids and has the potential to enhance the thermal conductivity of conventional heat transfer fluids.

Committee: Eric Vasquez Ph.D (Committee Chair); Soubantika Palchoudhury Ph.D (Committee Member); Kevin Myers D.Sc (Committee Member) Subjects: Chemical Engineering; Materials Science; Nanoscience

Doctor of Philosophy, University of Akron, 2021, Polymer Engineering

This work studies pigment dispersion in thermoset polyester powder coatings processed in an ultrasonic twin screw extruder (UTSE) and the real-time film formation process of methyl methacrylate (MMA) maintenance coatings. First, pigment dispersion of thermoset polyester powder coatings processed in an ultrasonic twin screw extruder (UTSE) was analyzed. A high Tg carboxylic functionalized polyester coating was extruded at several barrel temperatures and ultrasonic amplitudes. Two different crosslinkers, Triglycidylisocyanurate (TGIC) and β-hydroxyalkylamide (HAA), and pigments, TiO2 (PW6) and Phthalocyanine Blue (PB15:3), were studied. The extrudate was analyzed to quantify the amount of premature curing that occurred during extrusion via DSC. Powder coatings were created and applied to aluminum panels to study dispersion through gloss and color. It was determined that TGIC coatings had a higher risk of premature crosslinking when processed at temperatures above the crosslinker's melting point. Ultrasonic treatment was shown to improve the hue (h) of PB15 pigmented coatings and improve the lightness (L*) of TiO2 pigmented coatings. Processing was improved by ultrasonic treatment, evident by a significant decrease in torque. Next, a low Tg polyester resin was extruded in the UTSE. The combination of using a lower Tg resin and a smaller die enabled higher ultrasonic amplitudes to be studied. HAA formulations processed at 100 and 130°C, with and without a dispersion agent, were compared to each other. Scanning electron microscopy (SEM) and particle image analysis was used in addition to gloss and color change to visualize and quantify pigment dispersion. Ultrasound was shown to decrease UTSE torque, improve the hue of PB15 pigmented coatings, and improve the lightness (L*) of TiO2 pigmented coatings. SEM particle analysis revealed that ultrasound aided dispersion. Also, a model formulation of a methyl methacrylate (MMA) thermoset acrylic maintenance coating was devel (open full item for complete abstract)

Committee: Mark Soucek (Advisor); Kevin Cavicchi (Committee Chair); Fardin Khabaz (Committee Member); James Eagan (Committee Member); Sasa Dordevic (Committee Member) Subjects: Plastics; Polymer Chemistry; Polymers

Master of Science, University of Akron, 2020, Mechanical Engineering

Gears and bearings play a critical role as machine elements in automotive and wind turbine applications. High-performance thermoplastics can replace metals for load-bearing applications such as gear teeth due to their exceptional thermal and mechanical properties. However, there is a general lack of micropitting performance data for high-performance thermoplastics. This study attempts to address this by evaluating and comparing the performance of several high-performance thermoplastic families of materials using a micropitting rig. Rolling element bearing components suffer from high Hertzian stresses in service that cause micropitting. The stresses experienced by these mechanical components depends on factors such as loading, the degree of sliding motion, material composition, lubricant chemistry, and lubricant water contamination. Premature failures of automotive and wind turbine gearboxes have been reported, and efforts have been made to prolong the reliable life of these machine elements. A review of literature suggests that a comprehensive study of how lubricant water contamination, lubricant chemistry, and base oil properties affect the micropitting and wear of the widely used 52100 bearing steel has not yet been performed. In addition to evaluating the micropitting performance of high-performance gear thermoplastics, this study also aims to establish an understanding of the micropitting phenomena in bearing steel and how it is influenced by tribological and lubrication conditions. A range of chemically active additives are formulated into mineral and synthetic oils to analyze their relative performance using techniques such as optical profilometry, ICP-MS, and SEM/EDS. The results show that polyamide-imides (PAI) have superior micropitting performance of the thermoplastics considered. This is due to their exceptional dimensional stability and mechanical strength at elevated temperatures. It is also seen that chemically active lubricant additives (open full item for complete abstract)

Committee: Gary L. Doll PhD (Advisor); Manigandan Kannan PhD (Committee Member) Subjects: Materials Science; Mechanical Engineering

PhD, University of Cincinnati, 2019, Engineering and Applied Science: Materials Science

Worm-like micelles (WLMs) are important to many commercial products such as shampoo and body wash as well as industrial applications for enhanced viscosity additives and vehicles for drug delivery. Control over the properties of WLMs depends on a quantitative understanding of the impact of commonly used industrial additives and salt on the structure of WLMs and the details of the ion distribution at the surface of these robust, self-assembled nanostructures.

Committee: Gregory Beaucage Ph.D. (Committee Chair); Jude Iroh Ph.D. (Committee Member); Dale Schaefer Ph.D. (Committee Member); Karsten Vogtt Ph.D. (Committee Member); Michael Weaver Ph.D. (Committee Member) Subjects: Materials Science

Doctor of Philosophy, Case Western Reserve University, 2018, Chemical Engineering

Commercial plating systems typically utilize an electrolyte containing the plated ion in combination with additive mixtures consisting of multiple organic surface active species. These additives adsorb on the plated electrode, modifying the deposit properties, texture, and distribution. While some of the mechanistic details of the additives adsorption and interactions have been characterized, the effects of convective flow and particularly of complex current waveforms remain uncharted. A specific motivation for the research reported herein, is the preferential fill, by electroplated copper, of blind and open vias in printed circuit boards that is achieved utilizing special additives in combination with the application of periodic reverse current waveform in the presence of ferric ions and complex flow. The process, which is widely utilized, has been developed empirically. Its optimization requires understanding the effects of each process parameter, its quantification, and the development of a comprehensive quantitative model. The additives utilized in this study are polyethylene glycol (PEG) which is a copper deposition inhibitor, and bis-sodiumsulfopropyl-disulfide (SPS), which is a weak accelerator. Those very same additives enable the bottom-up metallization of semiconductor interconnects; however, due to the much larger metallized features (hundreds of microns vs. few nanometers) and much longer deposition time (order of hour instead of a few seconds), the challenges facing the plating process herein, are different and, in many cases, more complex. A quantitative model describing competitive adsorption of additives and polarization effects was developed to address deficiencies in current theories. This model, invoking heterogeneous adsorption energy sites, accounts for the steady-state additives (SPS and polyethylene glycol, `PEG') coverages, subject to competitive adsorption, as a function of additives concentration in solution, and accurately predic (open full item for complete abstract)

Committee: Uziel Landau (Advisor); Rohan Akolkar (Committee Member); Heidi Martin (Committee Member); Daniel Scherson (Committee Member) Subjects: Chemical Engineering

Bachelor of Science (BS), Ohio University, 2018, Physics

High frequency electromagnetic waves are essential for communications through earth's atmosphere for things such as missiles and satellites. While semi-conductor materials have replaced many uses of thermionic cathodes, semi-conductors cannot be used to create high frequency communications which are essential for national security. The current best thermionic cathodes, scandate cathodes, have reproducibility issues and are not well understood with regards to how the cathodes achieve low work functions that make them good electron emitters. I attempted to learn more about how these thermionic cathodes establish low work function surfaces by looking at the electron emission of cathodes with and without additives by measuring current vs voltage curves. I found that the cathodes with additives had better electron emission at similar temperatures which means that they have lower work functions.

Committee: Martin Kordesch (Advisor) Subjects: Physics

Doctor of Philosophy, Case Western Reserve University, 2017, Chemical Engineering

Metal deposition in electroless plating can be advantageously used to metalize non-conducting substrates and electrically isolated features. This research focuses on the metallization of nanometer-scale interconnects in semiconductor devices, which are rapidly approaching sizes too narrow for electroplating. A number of challenges still exist for the application of electroless plating to feature fill: (i) identifying an additives mixture that provides bottom-up fill in electroless plating; (ii) developing an experimental technique for rapid screening of such additives; (iii) quantification of transport in the electroless system; (iv) a comprehensive, quantitative model for electroless plating rates as a function of the important system parameters must be developed in order to enable predictive design. This research addresses all the above listed items. A technique for simulation of feature fill by electroless plating on a flat, non-patterned rotating disk electrode (RDE) is presented. Using deposition experiments performed at two different rotation speeds to simulate the feature top and bottom. This technique that provides a rapid and inexpensive method for additives screening, was used to identify promising additives for bottom-up fill. 3-mercaptopropanesulfonic acid (MPS) was identified as a promising additive for bottom-up fill, with polypropylene glycol (PPG) and 2'-2'-dipyridyl included in an additive mixture to provide a bright and uniform deposit. A model that provides electroless plating rates and accounts for the reactants and additives concentrations and for the effects of transport, has been developed. The model is based on experimental data and the electrochemical rate equations for both the oxidation and reduction reactions to provide the plating rate and operating potential as a function of the bulk reactants concentrations and the RDE rotation rate. The additives activity has been accounted for through the determination of their surface concentratio (open full item for complete abstract)

Committee: Uziel Landau (Advisor); Rohan Akolkar (Committee Member); Robert Savinell (Committee Member); Daniel Scherson (Committee Member) Subjects: Chemical Engineering; Chemistry; Engineering

Master of Sciences (Engineering), Case Western Reserve University, 2017, Macromolecular Science and Engineering

The flame retardant properties of deoxyribonucleic acid (DNA) were investigated in melt-processed low-density polyethylene (LDPE) and polystyrene (PS). DNA showed increased compatibility with the LDPE polymer matrix relative to industrially used intumescent melamine polyphosphate (MPP). Addition of DNA to polymer substrates resulted in a significantly smaller compounding torque relative to MPP samples. Furthermore, DNA in both substrates reduced burn distance during horizontal burn testing at loading levels above 5% w/w and 10% w/w for LDPE and PS respectively. PS samples subjected to larger scale mixing with repeated heat processing had comparable flame retardant properties to single step compounded samples. This research both broadens the field of green flame retardant additives and highlights the capacity of DNA to act as an all-in-one intumescent flame retardant additive in large-scale commodity polymer applications.

Committee: Jonathan Pokorski Ph.D. (Advisor); David Schiraldi Ph.D (Committee Member); Gary Wnek Ph.D. (Committee Member) Subjects: Polymers

Doctor of Philosophy, The Ohio State University, 1978, Graduate School

Committee: Not Provided (Other) Subjects: Psychology

Doctor of Philosophy, The Ohio State University, 1974, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture

Doctor of Philosophy, University of Akron, 2015, Mechanical Engineering

A global study performed in 1966 revealed that nearly 30% of the energy produced is spent to overcome friction and associated losses. A new interdisciplinary domain "Tribology" was defined in the "Jost Report"' as the branch of science that essentially deals with friction, wear and lubrication. Increasing demand to improve efficiency of mechanical systems has stimulated the research in tribology over the last few decades. Surface engineering methods are state of art techniques that are being adapted by industries including bearing manufacturers to address friction and wear issues. Many new and novel coatings have been developed for specific applications, but few if any, have improved the tribological performance of the most widely used components: ball bearings. Thus, there is a need for new tribological research designed to understand the influence of the coatings deposited onto spherical rolling elements in tribological contacts, and minimize losses due to friction and wear. In this work, thin films were deposited onto spherical rolling elements and the performance of the coated balls was evaluated under different conditions. The study revealed that ball coatings improves the performance of bearings, but coatings need to be selected based on application requirements to avail the benefits of coated balls.

Committee: Gary Doll (Advisor) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2014, Food Science and Technology

In processed tomato products, temperature, NaCl, protein, sucrose, and oil are varied due to consumer consumption conditions and preference while pectin is used as a thickener and pH may be adjusted to keep tomato products out of the low acid food category. The goal of this study was to determine how temperature, pH, and food additives affect the headspace volatile concentration and consumer acceptability of the aroma of flavored tomato products. Temperature (5, 25, 50 °C), pH (2.5, 4.3, 8.5), 1% pectin, 1% whey, collagen or milk protein, NaCl (5, 10%) sucrose (5, 10%), and oil (5, 10%) were varied in tomato juice, as a model for flavored tomato sauces, to determine the effect on volatile levels. The headspace concentrations of different tomato juice samples were measured by selected ion flow tube-mass spectrometry and sensory evaluation was conducted with fifty untrained consumers. Temperature produced the greatest increase, followed by the addition of NaCl. pH and pectin produced no significant difference, while protein, sucrose, and oil decreased volatile levels. 10% Oil changed the order of the odor activity values of important tomato volatiles while the rest did not, which can change the aroma perceived by the consumer. Sensory testing showed that NaCl, control, and sucrose had the highest aroma intensity and consumer preference followed by pectin and milk protein and finally oil. The higher the volatile concentration the stronger the consumer preference.

Committee: Sheryl Barringer Prof. (Advisor); Luis Rodriguez-Saona Prof. (Committee Member); Farnaz Maleky Asst. Prof. (Committee Member) Subjects: Food Science

Doctor of Philosophy, The Ohio State University, 2013, Neuroscience Graduate Studies Program

Autism spectrum disorders are complex and polygenic in nature. Twin studies indicate a role for genetic and environmental factors in the etiology of autism. Environmental influences during prenatal period could adversely affect fetal development. We have attempted to study the effect of different environmental factors on the susceptibility to develop autism. First, we looked at effect of prenatal exposure to diesel exhaust particles on autism spectrum disorders. We hypothesized that exposure to diesel exhaust particles during pregnancy can induce autism-like behaviors in offspring. In order to test this, we exposed pregnant mice to high concentration of diesel exhaust particles. We found that mice exposed to diesel exhaust particles during pre and postnatal development showed increased basal locomotor activity. These mice also display increased rearing behaviors and elevated levels of repetitive self-grooming in the presence of an unfamiliar mice. However, no deficits in social interaction, social communication or anxiety-like behavior were found. These results suggest that perinatal exposure to diesel exhaust particles have an impact on mouse development leading to observable changes in mouse behavior, however it may not affect fetal development in a manner that leads to very obvious deficits in social behaviors. Second, we tested if exposure to food additives during pregnancy induced autism-like behavior in the offspring. We fed pregnant mice with different kinds of food additives and tested the offspring for autism-like behavior. We report that a subset of mice exhibit reduced social interaction following additive treatment, although there were other groups of additives that had no effect on mouse social behaviors. These findings are preliminary and studies are currently on-going to consolidate these findings. Third, we generated a knockin mouse of protein tyrosine phosphatase protein (PTPRT). PTPRT is a transmembrane receptor protein that is expressed in high le (open full item for complete abstract)

Committee: Howard Gu Dr (Advisor) Subjects: Neurosciences

Master of Science, University of Toledo, 2011, Mechanical Engineering

Metal energetic additives are added to propellants and explosives to improve ignition and combustion performance. In particular, aluminum has been used as an energetic material in solid-based propellant rockets and explosives for many years due to its high combustion enthalpy and low cost. Recently, the introduction of nanotechnology has led to significant developments in the field of energetic materials. Nanoscale energetic materials, due to their surface area and unique thermal properties, are known to exhibit many advantages over conventional micron sized particles. However, the current mechanisms of nanoaluminum ignition and combustion are not fully understood. Furthermore, studies involving suspensions of energetic nanomaterials in a liquid medium (nanofluids) are very limited. A fundamental understanding of micron and nanoscale aluminum combustion is critical to the design and implementation of practical propulsion systems that use aluminum additives. Therefore, a comprehensive review on the ignition and combustion of energetic nanoparticles was performed, with a primary focus on aluminum, and two novel experimental studies were performed to investigate the combustion characteristics of nanoscale aluminum (n-Al) and aluminum oxide (n-Al2O3) in liquid fuels, namely, ethanol (C2H5OH). The first experimental study examined the heating values of several nanofluid suspensions of n-Al (50 nm) and n-Al2O3 (36 nm) in ethanol. The primary objective of this experimental study was to characterize the combustion reaction and gain a better understanding of nanoaluminum oxidation in a multi-component heterogeneous system. The heat of combustion was studied using a modified static bomb calorimeter system. Combustion experiments were performed with volume fractions of 1%, 3%, 5%, 7%, and 10% for n-Al, and 0.5 %, 1%, 3%, and 5% for n-Al2O3. Combustion element composition and surface morphology were evaluated using a scanning electron microscope and energy dispersive spectros (open full item for complete abstract)

Committee: Calvin Li PhD (Advisor); Matthew Franchetti PhD (Committee Member); Yong Gan PhD (Committee Member) Subjects: Mechanical Engineering

Master of Science in Industrial Engineering, University of Toledo, 2010, Industrial Engineering

Nowadays, the use of brittle materials rapidly increases in electronics and optical industries. However, these materials are very difficult to be handled in conventional machining due to their significant hardness and brittleness. Originated in Japan, Electrolytic In-Process Dressing (ELID) is a relatively new but quite efficient technology especially serves this area. Benefiting from electrolysis effect, ELID continuously maintains an oxide layer on grinding wheel which can considerably reduce normal grinding force. This In-Process dressing eliminates redundant wheel dressing so as to make it possible to achieve mirror-like surface finish. From literature review, predecessors have numerous studies on external factors, such as Voltage, Fluid Velocity, depth of Cut, et al. As electrolyte, fluids used in ELID draws author's major interest in how they perform when combined with various pH and concentration. By adding different kinds of additives, researcher alters the properties of the fluids and analyzes the results through the corresponding change in layer thicknesses. In the end, factorial design is utilized to study the data and to build the regression model, with which the oxide layer generation can be controlled and designated ultimately. The research reveals the most important factor that dominates the oxide layer generation is the kind of additive itself, which doesn't vary regardless other circumstances, such as concentration, strength of the alkali, or pH value.

Committee: Ioan D. Marinescu PhD (Advisor); Ahalapitiya H. Jayatissa PhD (Committee Member); Mehdi Pourazady PhD (Committee Member) Subjects: Industrial Engineering

Doctor of Philosophy, The Ohio State University, 2005, Chemistry

The conformational behavior of unnatural dendritic macromolecules was investigated in efforts to elucidate the factors mitigating solution conformational stability and to develop applications that utilize these properties. Chiral, amphiphilic dendrimers based on 2,3-dihydroxybenzyl alcohol were synthesized via iterative phenolic coupling, reduction, and bromination protocols and their solution conformational properties were evaluated using circular dichroism (CD)spectroscopy. Chirality transfer from the chiral core to the 2,3-dihydroxybenzyl ether branching units was observed only at the first generation and in pH 7 water. No CD signals were observed for any higher generation dendrimers in water or for all dendrimers in organic solvent. Ultimately, hydrophobic compression effects were not powerful enough to induce stable, secondary structures in these flexible molecules and suggested more significant non-covalent or covalent interactions are required to rigidify dendritic scaffolds. However, the globular and highly-branching nature of the 2,3-dihydroxybenzyl motif was utilized in the development of low-viscosity dental composite additives. Dental composites were formulated with varying percentages of novel multi-methacrylated dendritic additives and evaluated for the additives' influence on material properties. The flexural strength of composites containing only 2% dendritic additive exhibited from 21% to 35% increases in stress-to-break with increasing additive Mw compared to control composite. Higher concentrations of additive had either no significant effect or detrimental effects on the composite strength. The degree of polymerization decreased with increasing additive Mw and concentration, indicating a strong dependency of the photopolymerization rate on the additives' diffusion coefficient. Low concentrations of dendritic additive also affected as high as a 60% decrease in acetone-extractable material from the cured composite matrix. These studies demonstrate (open full item for complete abstract)

Committee: Jonathan Parquette (Advisor) Subjects: Chemistry, Organic

Master of Science (M.S.), University of Dayton, 2012, Mechanical Engineering

The objective of this study is to investigate the effects of aliphatic and aromatic halogenated additives on soot and PAH formation (polycyclic aromatic hydrocarbon) using a laminar co-flow ethylene-air diffusion flame. Both aliphatic surrogates (bromobutane, chlorobutane and bromo/chlorobutane mix) and aromatic surrogates (benzene, bromobenzene, chlorobenzene and bromo/chlorobenzene mix) were added to the base fuel for investigation. The soot particles were collected on quartz filters and their mass was determined using a Leco carbon burn-off method. The gaseous effluents were collected in an Amberlite XAD-2 sorbent trap and extracted using the Soxhlet technique. Gas chromatography / mass spectrometry (GC/MS) was used to identify and quantify the extracted gaseous effluents. Significant amounts of enols were detected along with PAHs, indicating that enols are also important intermediate species in hydrocarbon combustion. The results showed that all the halogenated additives reduced the temperature of the sampling system, indicating flame suppression properties. All the additives gave increased soot yields when compared to the baseline experiment. The brominated fuel additives displayed a higher propensity to soot than the corresponding chlorinated fuel additives. The aromatic additives showed a greater tendency to soot than their aliphatic counterparts. All the additives increased the total PAH and enol yields, with benzene yielding the highest. The halogenated form of benzene decreased the total PAH and enol yields when compared to benzene, suggesting that halogens accelerate the conversion of PAHs to soot. The effect of bromine in increasing the total PAH and enol yields is more than that of chlorine.

Committee: Dr. Sukh Sidhu (Committee Chair); Dr. Philip Taylor (Committee Member); Dr. Moshan Kahandawala (Committee Member) Subjects: Aerospace Engineering; Analytical Chemistry; Automotive Engineering; Chemical Engineering; Chemistry; Engineering; Environmental Engineering; Mechanical Engineering; Organic Chemistry; Petroleum Engineering