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Ethylene copolymers are widely used as packaging materials, adhesives and specialty polymers for well-regarded cost savings, durability, chemical resistance, and hot melt character. This work examines the use of diester monomers known as malonates to determine the plausibility of utilizing an uncommon monomer class for producing novel ethylene copolymers. Ethylene is copolymerized with diethyl methylene malonate—a simple malonate representative of more complex and highly modified malonate monomers and macromers—to produce ethylene-co-diethyl methylene malonate in a range of molecular weights. Ethylene-co-diethyl methylene malonate is analyzed to determine physical properties such as glass transition temperature, chain length and monomer incorporation. Successful copolymerization occurred under a range of temperatures and pressures in tetrahydrofuran, diethyl carbonate, and dimethyl carbonate. The produced polymers were found to have a molecular weight of 15-46 kg/mol, a glass transition temperature of 7°C, a melting temperature of 108°C, and a cold crystallization temperature of 64°C. The high concentration of a radical source inhibitor in the diethyl methylene malonate monomer solution negatively impacted molecular weight and ethylene incorporation.

<p> This dissertation describes an investigation into the free radical polymerization of styrene in continuous stirred tank reactors (CSTR's). The aim was to develop a steady state polymerization model which would accurately predict conversion and molecular weight distribution (MWD) up to high conversion. </p> <p> The dissertation is divided into three self-contained parts. Part I describes the testing and development of polymerization kinetics using a single CSTR. The single CSTR model is described. Theoretical and experimental conversions and MWD's are compared and discussed. </p> <p> Part II describes the development of a model for a system of CSTR's. It is based upon the single CSTR model and the kinetics developed in Part I. Theoretical and experimental results for a three reactor system are compared and discussed. </p> <p> Part III describes the development of gel permeation chromatography (GPC) for measuring MWD. Molecular weight and resolution calibration data are presented and discussed. Four methods of chromatogram interpretation that correct for imperfect resolution are compared. </p> / Thesis / Doctor of Philosophy (PhD)

<p> This thesis presents a study on silane based polymerization in two parts. </p> <p> In Part A, diphenylvinylsilane (1) underwent oligomerization with initiation by azo(bisisobutyronitrile) (AIBN) or benzoyl peroxide (BPO). The vinyl groups were preferentially consumed under either set of conditions. Several products were isolated; these included oligomers 3, an AIBN adduct 4, a dimer 5, and a trimer 6. The residual SiH moieties could be subsequently coupled hydrosilylatively with alkynes or vinylsilicones. The efficiency of the radical reactions was very low. 15% starting material was recovered even with 200 mol% of initiating radicals added to the reaction mixture. The relative radical reactivities of the two functional groups is discussed.</p> <p> In Part B, 1 was radically copolymerized with styrene and methyl methacrylate (MMA). From the results of infrared and 1H NMR it was determined that 1 participated in copolymerization via a vinyl type polymerization and not in the form of a hydrogen-transfer type polymerization. Residual SiH groups along the backbone of the polymer remained reactive. A vinylsilicone and 9-vinylanthracene were grafted onto the copolymer from MMA and 1 by hydrosilylation and radical methods, respectively.</p> / Thesis / Master of Science (MSc)

Melatonin is a natural antioxidant that has been investigated for properties as a potential spin trap to identify short-lived free radicals. Computational quantum chemistry studies have been performed for the oxidation of melatonin to N1-acetyl-N2-formyl-5-methoxykynuramine. This research focused on modification of melatonin into derivatives and analyzing the change in total molecular energy from melatonin to its oxidation product, as well as the corresponding derivatives. Each of the molecular geometries were optimized at the DFT/B3LYP/6-31G(d), DFT/B3LYP/cc-pVXZ (X = D, T), HF/6-31G(d), HF/cc-PVXZ (X = D, T), MP2/6-31G(d), and MP2/cc-PVXZ (X = D, T) levels of theory. Single point energies were extrapolated to the complete basis set. The results demonstrated that some electron-withdrawing groups increased the total energy of the system. The electron-withdrawing functional group which lowered the total energy of the system was a peroxyl functional group, and this is believed to be due to overlapping constructive interference between molecular orbitals.

Indiana University-Purdue University Indianapolis (IUPUI) / Alkyl radicals are powerful intermediates for the generation of carbon-carbon bonds, which play an indispensable role in the synthesis of natural products, pharmaceuticals, and pesticides. Traditionally, there are two main methods for the generation of alkyl radicals. The first is C-H bond functionalization via hydrogen-atom-transfer (HAT). HAT processes have been used as an effective approach for selectively activating C-H bonds via radical pathways. The other strategy to explore the generation of alkyl radicals is C-X bond functionalization via halogen-atom-transfer (XAT). Alkyl halides are one of the largest classes of building blocks in synthesis and they can be obtained from the corresponding alcohols. The most straightforward and effective way to form such alkyl radicals is the direct homolytic cleavage of C-X bonds. In past decades, photoredox catalysis has emerged as a powerful and greener tool for the synthesis of radicals under mild reaction conditions, which has brought tremendous attention. Although remarkable success has been made in this field, some methods still require costly transition metal catalysts or toxic reagents. Herein, we display a series of visible light-induced approaches under transition-metal free conditions or using earth-abundant metals. These novel photo-induced transformations and corresponding mechanistic work will be discussed in the following order: We will first present our work on metal-free visible-light-promoted C(sp3)-H functionalization of aliphatic cyclic ethers using trace O2. This reaction uses a trace amount of aerobic oxygen as the sole green oxidant under blue light at room temperature to achieve the synthesis of sulfone and phosphate derivatives in good to excellent yields using cyclic ethers and vinyl sulfones. Then, we report on a photo-induced C(sp3)-H chalcogenation of amide derivatives and ethers via a ligand-to-metal charge-transfer. This reaction converts secondary and tertiary amides, sulfonamides, and carbamates into the corresponding amido-N,S-acetal derivatives in good yields, using an earth abundant metal catalyst under mild conditions. Finally, we present a photoredox polyfluoroarylation of alkyl halides via halogen atom transfer. This method converts primary, secondary, and tertiary unactivated abundant alkyl halides into the corresponding polyfluoroaryl compounds in good yields and has good functional group compatibility.

Low-temperature non–thermal plasmas are of growing interest due to their applications in various fields, such as plasma-assisted combustion, plasma medicine, material processing, etc. Hydroxyl radical (OH) is one of the key agents and most important reactive species generated in plasmas. We employ cavity ringdown spectroscopy (CRDS), both a pulsed laser and a continuous wave (cw) laser to measure absolute number densities of OH radicals in low-temperature plasmas. A 2.45 GHz microwave plasma source was used to excite two different types of plasma cavities: an atmospheric plasma jet and microwave plasma torch (MPT). The atmospheric microwave plasma jet was thoroughly explored and operated with different plasma gases. Plasma jets with argon (Ar), helium (He), Ar/N2, Ar/O2, He/N2, He/O2 and Ar/H2O were investigated. The absolute number densities of OH radicals were measured along the jet axis in all of plasma jets using pulsed CRDS. Effects of plasma power and gas flow rates on OH radical generation were also studied. We have reported for the first time that OH radicals exist in the far downstream region of a plasma jet axis. The far downstream is a location where the ratio of distance from the plasma jet orifice over the plasma jet column length is larger than 3. For an Ar plasma jet length of 3 mm, OH radicals were detected at a farthest distance ratio of 7.6. The OH density profiles along the axis in all the plasma jets indicate that OH radicals have the highest number density in the vicinity of the jet tip and gradually decreases in the downstream. Optical emission spectroscopy and digital imaging were simultaneously employed to identify the different radicals generated in plasma jets and to study the fine structures of the plasma jets. Pulsed CRDS was also employed to measure OH radical density in an Ar MPT. By using high temporal resolved imaging, it was observed that the widely reported converging point in Ar MPT is actually a time-averaged visual effect. Absolute number densities of OH radicals and water molecules were measured in an alternating current (AC) glow discharge using near infrared cw CRDS.

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