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

Bachelor of Science, Wittenberg University, 2021, Biology

Glyphosate has been shown to impact not only amphibian survival, but also their development, phenotypic response to predators, and overall behavior. Dicamba, another herbicide, was permitted for use by the EPA in 2016. However, less is known about its potential environmental impact. Being an extremely volatile chemical, dicamba poses a risk to aquatic organisms in areas that may experience runoff or overspray. It can also harm yields of neighboring crops, leading the EPA to ban dicamba use part way through this experiment in June 2020. We investigated the effects of an environmentally relevant dosage of two forms of dicamba on grey treefrog tadpole development and behavior. We also investigated how dicamba impacted the response of tadpoles to predator cues. Herbicide treatment significantly decreased growth compared to the control. The presence of predator cues also significantly decreased growth, and there was no interaction between herbicide treatment and predator treatment. Tadpoles exposed to predator cues generally had wider tails, and the introduction of dicamba caused similar morphological changes. The presence of commercial dicamba also significantly reduced startle responses, potentially increasing the risk for predation. Dicamba has the potential for sublethal impacts on the development and behavior of tadpoles, and therefore should be further studied.

Committee: Amber Burgett (Advisor); Richard Phillips (Committee Member); Doug Andrews (Committee Member) Subjects: Agricultural Chemicals; Animal Sciences; Animals; Aquatic Sciences; Biology; Environmental Science; Statistics; Zoology

Doctor of Philosophy, University of Akron, 2015, Chemistry

Polyphosphazenes represent the largest class of inorganic backbone polymers and a wide array of applications exists and continues to accumulate. Although many useful phosphazene polymer systems exist, commercial use has been limited due to irreproducibilities and high cost of the parent polymer, polydichlorophosphazene, from which most other polyphosphazenes are derived. Although the ring-opening polymerization of [PCl2N]3 has been extensively studied since the mid-1960s, the mechanism is still under much debate and the search for novel initiators to the process is ongoing. The majority of phosphazenes are derived from the chlorophosphazenes; however, the properties of the P-N backbone of phosphazenes can be greatly tuned with the addition of different side groups attached to the phosphorus atom. A large variety of applications for substituted phosphazene compounds have been developed ranging from biological materials that are water-degradable to phosphazene superbases that have been used as initiators for several organic polymerizations. The main focus of this dissertation is fundamental phosphazene chemistry ranging from investigations of the initiating steps of the ring-opening polymerization of [PCl2N]3 to interactions of phosphazene superbases with classic Lewis acids. This dissertation is divided into six chapters: introduction, interactions of phosphazene superbases with group 1 and group 12 Lewis acids, interactions of phosphazene superbases with group 13 Lewis acids, reaction of phosphazene superbases with [PCl2N]3, phosphazenes for biological applications, and conclusion. Chapter I provides an overall review of polyphosphazene synthesis including initiators and mechanistic discussions as well as use of phosphazene superbases as frustrated Lewis pairs and initiators in anionic ring-opening polymerizations. Chapter II contains explorations of phosphazene superbases and their interactions with group 1 and group 12 Lewis acids. Chapter III is a (open full item for complete abstract)

Committee: Claire Tessier Dr. (Advisor); Wiley Youngs Dr. (Committee Member); Peter Rinaldi Dr. (Committee Member); Chrys Wesdemiotis Dr. (Committee Member); Coleen Pugh Dr. (Committee Member) Subjects: Chemistry; Inorganic Chemistry

Master of Science, University of Akron, 2014, Polymer Science

Thermally stimulated fluctuations on polymer melts are important since they influence wetting, adhesion and friction. Study in this field has just begun recently. The most studied polymer is linear polystyrene (LPS) since it is easy to synthesize. A hydrodynamic continuum theory (HCT) that treats films as uniform layers of thickness, h, having bulk viscosity is able to explain surface fluctuations on melts of linear chains some times. The surface fluctuations can be characterized by a relaxation time, t, that varies with the value of the in-plane scattering vector, q. Kim and collaborators3 found that data for samples of different thicknesses, h(of which no confinement effect happens), collapse onto a single curve at a given temperature in the plot of t/h vs. qh, which is consistent with HCT model. However, deviations were observed in subsequent work at temperatures near Tg, for molecular weights, M, such that M > Mc, where Mc is the critical molecular weight for entanglements.1 Also, deviations were seen for very thin films with h<4 Rg, where Rg is radius of gyration.25 For very thin films, confinement effect induces the deviation. Wang and collaborators13 found that the confinement effect happens when the film is thinner than 10 Rg for 14k cyclic polystyrene (CPS). Subsequent work by He et al14. showed that for 6k CPS, data for films thinner than 20 Rg did not follow the HCT model, but no confinement effect was observed for the 6k LPS film even when thickness reaches 7 Rg. A tadpole-like polystyrene (TPS) has an architecture between that of CPS and LPS. It was synthesized using anionic polymerization via two synthetic approaches. The first route is to synthesize a functionalizable cyclic polystyrene with a silicon-hydrogen bond, which can be used for hydrosilylation to get the tadpole-like polystyrene. The second route is based on a metathesis ring-closure technique, which is used to cyclize two of the three arms in the 3-arms star precursor to create the tadp (open full item for complete abstract)

Committee: Mark Foster Dr. (Advisor); Roderic Quirk Dr. (Advisor) Subjects: Polymer Chemistry

Doctor of Philosophy (PhD), Ohio University, 2003, Biological Sciences (Arts and Sciences)

Interest in the evolution of the larval anuran chondrocranium has increased in recent years, with several studies attempting to use chondrocranial characters in phylogenetic reconstruction or assess the distribution of larval chondrocranial characters in the context of a hypothesized phylogeny. Despite this, very little is known about the function of the chondrocranium or how developmental factors contribute to interspecific morphological variation. Furthermore, analytical methods such as morphometric analyses have rarely been employed and offer the potential for providing new insights into the evolution of the larval anuran chondrocranium. This study examines the function, development, and evolution of the chondrocranium in larval anurans of the genus Rana (Anura: Ranidae) with the following goals: 1) To provide the first data on the function of tadpole cranial musculature during feeding; 2)To provide the first detailed data on chondrocranial allometry in a larval anuran (Rana sylvatica); 3)To qualitatively describe and compare the structure of the chondrocranium among six species of North American Rana, and to review chondrocranial anatomy within the Ranidae; 4)To quantitatively analyze variation in chondrocranial shape among species of Rana using multivariate morphometric methods; and 5)To compare allometric patterns among six species and assess the relationship between ontogeny, phylogeny, and chodrocranial morphology in larval Rana. Data on muscle function during feeding in larval Rana catesbeiana indicate that several muscles appear to be primarily feeding muscles (e.g., levator mandibulae group) whereas others appear to be have multiple functions (e.g. interhyoideus). Many of the "feeding" muscles are associated with regions of the chodrocranium that are variable in shape both ontogenetically and interspecifically. Results of comparative morphological studies indicate that although qualitative variation in chondrocranial morphology is limited, quantitative an (open full item for complete abstract)

Committee: Stephen Reilly (Advisor) Subjects: Biology, Anatomy

BS, Kent State University, 2013, College of Arts and Sciences / Department of Biological Sciences

Amphibians fill many niches within an ecosystem and have important interactions with other species in their habitats. In this study, wood frog (Lithobates sylvaticus) tadpole growth and development was monitored until metamorphosis under four different leaf litter treatments; red oak (Quercus rubra), red maple (Acer rubrum), American beech (Fagus grandifolia), and a mixture of the three in artificial pools that simulated their typical vernal pool habitat. While tadpole size, morphology, and developmental stage changed significantly over time, there were no significant effects of leaf litter treatment, nor were there significant time*treatment interaction effects. Following completion of the experiment, leaf chemistry analyses were also conducted to compare biochemical characteristics associated with different leaf litter treatments that might have implications for tadpole populations. Of the biochemical analyses, % polar extractives, % lignin, lignin:N, and % C were significantly different among treatments. Thus, despite leaf litter differences, tadpoles showed no significant treatment effects. These data indicate that wood frog tadpoles exhibit broader plasticity relative to vernal pool conditions than might be expected. Ultimately, this may make L. sylvaticus more resilient to changing upland forest communities, particularly with respect to tree species present.

Committee: Mark Kershner (Advisor); Chris Blackwood (Committee Member); Dan Ross (Committee Member); Paul Sampson (Committee Member) Subjects: Biology; Conservation; Ecology; Environmental Science; Evolution and Development; Freshwater Ecology; Organismal Biology; Plant Biology; Wildlife Conservation