Doctor of Philosophy, University of Akron, 2011, Polymer Science

A variety of methods were used to make polymers with different architecture and functionalities. The linking chemistry of vinyldimethylchlorosilane (VDMCS) with poly(styryl)lithium (Mn = 1,700-3,000 g/mol) was studied. The average degree of branching varied from 7.5 to 9.4 with an increase in concentration of VDMCS (1.2 to 5.2 eq). The intrinsic viscosities and melt viscosities (at 160 °C) of the star polymers were found to be less than half of that of the corresponding linear polystyrenes. α-Pyrrolidine-functionalized polystyrene (Mn = 2,700 g/mol, Mw/Mn = 1.03, 92.5%) was successfully synthesized from α-chloromethyldimethylsilane-functionalized polystyrene(Mn = 2,600 g/mol, Mw/Mn = 1.02) based on NMR spectroscopy, MALDI-TOF and ESI mass spectrometry. The stability of silyl hydride groups under atom transfer radical polymerization conditions was proven by copolymerizing methyl methacrylate and (4-vinylphenyl)dimethylsilane (VPDS). Tapered block copolymers of isoprene, VPDS, and styrene with narrow molecular weight distributions (1.04 and 1.05) were synthesized via anionic polymerization. Evidence regarding the topology of cyclic polybutadienes was obtained by Atomic Force Microscopy of grafted polymers obtained by grafting an excess of silyl hydride functionalized polystyrene (Mn = 8,300 g/mol, Mw/Mn =1.01) onto cyclic polybutadiene(Mn=88,000 g/mol, Mw/Mn = 2.0). The reactivity of polyisobutylene carbocations was compared with respect to competitive electrophilic addition to a vinyl group versus silyl hydride transfer by investigating the reaction with VPDS. Based on GPC results, and 1H and 13C NMR spectroscopy, no evidence for any vinyl group addition was observed. A successful attempt was made to prepare electrospun fibers from fluorofunctionalized styrene-butadiene elastomers. The water contact angle of these surfaces was found to be 162.8o ± 3.8o for the fibrous mat of the fluorinated polymers as compared to 151.2o ± 2.4o for the analogous fibrous (open full item for complete abstract)

Committee: Roderic Quirk Dr. (Advisor); Mark Foster Dr. (Committee Chair); Judit Puskas Dr. (Committee Member); Chrys Wesdemiotis Dr. (Committee Member); Kevin Cavicchi Dr. (Committee Member) Subjects: Polymers

Doctor of Philosophy, University of Toledo, 2021, Engineering

Thermoplastic elastomers (TPEs) are a class of materials known for their low Young's modulus and high yield strain. Their applications range from adhesives and seals to automotive parts, footwear, and medical components. This dissertation aims to develop new applications for styrenic TPEs in areas of stimuli sensing and winter safety. First, TPEs with controlled volumetric shape change sensitive to heat and chemical vapors are developed through the concept of dynamic porosity. Dynamically porous films are developed mainly from poly(styrene-ethylene/butylene-styrene) (SEBS) using an eco-friendly CO2 manufacturing method. It is shown that omnidirectional pore size changes above a glass transition temperature (Tg) for polystyrene (PS) physical crosslinks (i.e. 125 °C), which imparts the films with a controlled pore density and a porous-to-solid transition (PST). The tunable PST at a specific temperature is also concomitant with an opaque-to-transparent transition (OTT) useful for indication/detection of temperature. The PST and OTT concepts were further exploited for developments of actuators and vapor responsive films. The second part of this dissertation describes the development of an unconventional and facile strategy for crafting dynamically porous TPEs with an ability to undergo a PST in response to applied mechanical contact pressure at ambient conditions. The PST is shown to be reversible for multiple cycles by applying an in-plane stretch on the activated non-porous films. The PST transition leads to a three orders of magnitude reduction of pore density, resulting in a strong OTT contrast, which can act as a visual indicator for pore reversion and re-generation. Finally, it is shown that the pore reversion can be exploited to locally control the films' mechanical and heat transfer characteristics. Given thousands of injuries involved with ice, sleet, or snow during winter, the development of surfaces with enhanced grip on such slippery surfaces would be deem (open full item for complete abstract)

Committee: Reza Rizvi (Advisor) Subjects: Engineering; Materials Science; Mechanical Engineering; Polymers

Doctor of Philosophy, University of Akron, 2006, Polymer Engineering

Three segmented main-chain thermotropic liquid crystalline polymers (TLCPs) functionalized with nitrogen-containing heterocyclic groups were synthesized; namely PyHQ12 having pendent pyridyl group, PABP having side-chain azopyridyl group with flexible spacer, and PTBP containing side-chain terpyridine group with flexible spacer. The principles of specific interactions were applied to prepare supramolecular structures and organoclay or clay nanocomposites based on these functional TLCPs. Three combined main-chain/side-chain liquid-crystalline polymers (MCSCLCPs) were prepared via hydrogen bonding or ionic interactions based on PyHQ12 and PABP. The presence of hydrogen bonds in self-assembled PyHQ12-7CNCOOH and PABP-AA, and the presence of ionic interactions in self-assembled PABP-TSA, which exist above their respective clearing temperatures, were confirmed using Fourier transform infrared (FTIR) spectroscopy, the thermal transitions in each MCSCLCP were determined using differential scanning calorimetry (DSC), and the mesophase structures of each self-assembled MCSCLCP were characterized using polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). PyHQ12 was observed to be very effective in exfoliating organoclay (Cloisite 30B) aggregates, because of the formation of hydrogen bonds, as determined by in situ FTIR spectroscopy, between the pendent pyridyl group in PyHQ12 and the hydroxyl groups in the surfactant MT2EtOH residing at the surface of Cloisite 30B. Thus, functionality in TLCP is necessary to obtain highly dispersed organoclay nanocomposites, but at the same time there is a possibility to lose some degree of liquid crystallinity in the TLCP, due to the proximity of the pendent pyridyl group to the mesogenic main-chain backbone. Thus, another functional TLCP, PABP having side-chain azopyridyl group with flexible spacer, was synthesized. It has been found that the liquid crystallinity of PABP in the organoclay nanocomposites was more or le (open full item for complete abstract)

Committee: Chang Dae Han (Advisor); Mark Soucek (Other); Kyonsuku Min (Other); Stephen Cheng (Other); Jun Hu (Other) Subjects:

Master of Science, The Ohio State University, 2005, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science (MS), Wright State University, 2024, Chemistry

Thermally activated delayed fluorescence (TADF) small molecules have dominated the literature for their use in OLED devices. The use of TADF polymers has been employed to correct for processing issues that small molecules face, providing increased thermal stability and supportive electronic structures. A TADF chromophore based on a 2-(2,6-difluorophenyl)-benzothiazole-carbazole donor-acceptor pair was synthesized via a copper (I) catalyzed reaction. The chromophore exhibited peak absorption at 340 nm and emission at 477 nm. The resulting chromophore was incorporated into a poly(arylene ether) (PAE) backbone via nucleophilic aromatic substitution (NAS) with 4,4'-biphenol, 4,4'-difluorodiphenyl sulfone, and 2-(2,6-difluorophenyl)-benzothiazole as comonomers. UV/Vis analysis of the polymers in solution in NMP found that peak absorption values ranged from 319 nm to 340 nm. Fluorescence of the polymers found peak emission ranging from 452 nm to 456 nm. Absorption and emission characteristics of polymers are attributed to incorporation of the chromophore. Analysis by differential scanning calorimetry (DSC) determined that the addition of chromophore to a BPDPS backbone decreased glass transition temperatures and improved glass transition temperatures in BP-BTZ polymers when content was increased from 10% to 15%. The final blue-emitting polymers reflected the benefits of increased thermal stability seen in other PAE species as well as the retention of photophysical properties observed by the blue-emitting TADF chromophore.

Committee: Eric Fossum Ph.D. (Advisor); Rachel Aga Ph.D. (Committee Member); Travis Clark Ph.D. (Committee Member) Subjects: Chemistry

Doctor of Philosophy, University of Akron, 2023, Polymer Engineering

One-way shape memory polymers (SMPs) possess the unique ability to remember a programmed 'temporary shape' and revert to its original shape when exposed to an external stimulus. Typically, SMPs contain two structure-spanning, solid networks; a permanent elastic network that is strained during programming to drive shape recovery; and a temporary network that fixes the programmed shape. The shape-shifting features of SMPs make them useful for a wide range of potential applications, including 4D printing, soft robotics, flexible electronics, soft aeronautical engineering, and biomedical devices. An interesting pathway to develop SMPs is by blending an elastomer and a crystalline small molecule, where the elastomer forms the permanent network (that promotes shape recovery), and the small molecule crystal forms the temporary networks (that promotes shape fixity). Typical examples of these systems include crosslinked elastomers (natural rubber) swelled in fatty acids (lauric acid, stearic acid, and palmitic acid), straight-chain alkanes (eicosane, tetracosane) or synthetic waxes (paraffin wax). However, a drawback of this approach is the blooming and expulsion of the small molecule during shape programming and recovery. This dissertation attempts to focus on semi-crystalline shape memory elastomers developed from blends of high cis 1,4 polybutadiene and reactive monomers (octadecyl acrylate and benzyl methacrylate) or molecular crystals (n-eicosane and n-tetracosane) with the aim being reducing the effect of blooming while keeping a simple fabrication route to develop these SMPs. The synthetic, network, mechanical, thermal, and morphological properties of a series of polybutadiene-based semicrystalline or glassy blends were studied to understand the structureproperty relationships between their permanent and reversible networks. Furthermore, it will be shown that thermally annealed high cis 1,4 polybutadiene also demonstrates thermoresponsive actuatio (open full item for complete abstract)

Committee: Kevin Cavichhi (Advisor); Fardin Khabaz (Committee Chair); Qixin Zhou (Committee Member); Li Jia (Committee Member); Weinan Xu (Committee Member) Subjects: Chemistry; Materials Science; Plastics

Doctor of Philosophy, The Ohio State University, 2023, Mechanical Engineering

Lithium-ion (Li-ion) batteries adopted in electric vehicles (EVs) require significant increase in energy density (> 750 Wh/L) and reduction of costs to enable widespread commercialization. To address these challenges, R&D efforts have been directed towards (a) finding materials with high energy density (b) improving electrode design and (c) enhancing conductivity of the electrode materials. The former strategy involves implementing Nickel and Manganese based chemistries such as NMC, LNMO. In particular, the LNMO spinel cathode material is a promising material which provides high energy densities of 650 Wh/kg due to increased operating voltage of 4.75 Vvs Li/Li+. However, the increased voltage also accelerates oxidative decomposition reactions in the electrolyte and causes capacity fade in LNMO full cells paired with graphite anode. Using a composite binder can help passivate the carbon and cathode material surfaces against decomposition products from the electrolyte. Further, the composite binder also has the advantage of using water as the solvent making the process environmentally benign and cheaper compared with currently adopted N-Methyl 2-Pyrrolidone (NMP) solvent. The second strategy includes minimizing the use of inactive materials (e.g., current collectors and separators) and increasing the thickness of electrodes (> 250 µm), which in turn offers improved energy density with reduced cost. To achieve this an aqueous composite binder system is utilized which can sustain high thickness of electrodes while creating unique electrode architectures conducive to ionic and electronic conductivity. The third strategy utilizes a conductive polymer additive to create ion and electron conducting interfaces across the cathode material surface thereby providing better cycle and rate performance. The performance improvement in each of these strategies is demonstrated through electrochemical tests and their mechanisms are understood by utilizing several characterization tec (open full item for complete abstract)

Committee: Jung Hyun Kim (Advisor); Jay Sayre (Committee Member); Hanna Cho (Committee Member); Christopher Brooks (Committee Member) Subjects: Automotive Engineering; Automotive Materials; Materials Science; Mechanical Engineering

Doctor of Philosophy, Miami University, 2023, Chemistry and Biochemistry

In the future, well-engineered and optimized flexible electronic devices will be woven into everyday accessories such as clothes, furniture, safety, and healthcare monitoring devices. Dynamic polymer nanocomposites (DPNs) are an excellent class of materials that have a huge potential in the future of flexible electronics. DPNs are achieved through macromolecular engineering of dynamic polymers enhanced with electrically conductive nanofillers or nanocomposites with self-healing capabilities enabled via dynamic chemical linkages. Integration of multiple types of dynamic linkages into one polymer network is challenging and not well understood especially in the design and fabrication of DPNs. This dissertation presents facile methods for synthesizing flexible, healable, conductive, recyclable, and thermoresponsive DPNs using three dynamic chemistries playing distinct roles. Dynamic hydrogen bonds account for material flexibility and recycling character. Thiol-Michael exchange accounts for thermoresponsive properties. Diels-Alder reaction leads to covalent bonding between polymer matrix and nanocomposite. Overall, the presence of multiple types of orthogonal dynamic bonds provided a solution to the trade-off between enhanced mechanical performance and material elongation in DPNs. Efficient reinforcement was achieved using <1 wt.% carbon nanotubes (CNT) as nanofillers. Increased mechanical strength, electrical conductivity, and re-processability were achieved all while maintaining material flexibility and extensibility, hence highlight the strong promise of these DPNs in the rapidly growing fields of flexible compliant electrodes. Additionally, structure-property relationships highlighting the impact of network architecture, chain-length, cross-link density, and CNT loading are explored. Controlled addition of CNT as nanofiller produces electrically conductive and mechanically enhanced DPNs with demonstrated application in the regulation of current flow towards a (open full item for complete abstract)

Committee: Dominik Konkolewicz d.konkolewicz@miamioh.edu (Advisor) Subjects: Chemistry; Materials Science; Nanoscience; Organic Chemistry; Physical Chemistry

Master of Science, The Ohio State University, 2021, Biomedical Engineering

Cathepsin B is a lysosomal cysteine protease that has a variety of functions intracellularly in healthy cells. However, in certain physiological processes, such as wound healing, and in several disease states, like cancer, cathepsin B is secreted extracellularly and is involved in matrix degradation. Cathepsin B's extracellular proteolytic activity is thought to play an important role in cancer progression and metastasis. Measuring cathepsin B's extracellular activity has been proven difficult. Gene and protein expression levels are often not representative of the true extracellular activity of cathepsin B, because a variety of factors influence the activity such as pH, various inhibitors, and the amount that is secreted extracellularly. Thus, multiple cathepsin B-cleavable fluorescent peptide biosensors have been created to specifically measure the activity of cathepsin B. But, these biosensors have been designed to be used in-solution, which is not always representative of the environment cancer cells experience in vivo. We redesigned a cathepsin B-cleavable fluorescent peptide biosensor, so it can be conjugated into poly(ethylene glycol) (PEG) hydrogels. Cathepsin B activity then can be measured in three-dimensional (3D) matrices that are more representative of the in vivo microenvironment. In addition to investigating the regulation of extracellular cathepsin B activity of cancer cells, this cleavable, fluorescent peptide can be used in other ways in the future. We demonstrate that a similar fluorescent peptide for matrix metalloproteinases (MMPs), another enzyme contributing to the cleavage of the extracellular matrix, conjugated to a cancer drug has the potential to be used as a drug delivery platform. Another further goal for the cathepsin B biosensor is to perform a drug screen on encapsulated patient tissue to examine the impact of cancer drugs on cathepsin B activity to inform personalized treatment decisions. Overall, designing a cathepsin B-cleavable b (open full item for complete abstract)

Committee: Aleksander Skardal (Committee Member); Jennifer Leight (Advisor) Subjects: Biomedical Engineering; Biomedical Research; Polymer Chemistry; Polymers

Master of Science, University of Akron, 2021, Polymer Science

Ring-opening metathesis polymerization (ROMP) is now playing an important role in synthesizing macromolecular materials. However, existing systems for living ROMP cannot be depolymerized. Herein, 5, 6-trans-cyclobutane-fused E-cyclooctene derivatives are investigated. This system not only enables the monomer to be polymerized via living ROMP under mild, ambient conditions but also allows the resulting polymer to be depolymerized. The E-cyclooctene provides a higher ring strain for living ROMP, while the fused cyclobutane regulates the ring strain to enable depolymerization via ring-closing metathesis (RCM) depolymerization. Cyclobutane-fused E-cyclooctene monomers with two different functional groups are synthesized. The monomer functionalized with butyl esters would form a polymer melt, while the monomer with phenyl maleimide would form a glassy polymer. Polymers with narrow molecular weight distribution are gained from a preliminary polymerization. Based on the features of living ROMP, the above-mentioned monomers possess the potential to form diblock copolymers by sequential addition. The ability to be depolymerized under Grubbs' catalyst is demonstrated as well, indicating that this system can be chemically recycled. Thus, this depolymerizable ROMP system can contribute to the global efforts to alleviate the current environmental situations.

Committee: Junpeng Wang (Advisor); Chunming Liu (Committee Member) Subjects: Polymer Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2020, Polymer Science

Versatile Ring-Opening Copolymerization and Postprinting Functionalization of Lactone and Poly(propylene fumarate) Block Copolymers: Resorbable Building Blocks for Additive Manufacturing. Additive manufacturing has the potential to change medicine, but clinical applications are limited by a lack of resorbable, printable materials. Herein, we report the first synthesis of polylactone and poly(propylene fumarate) (PPF) block copolymers with well-defined molecular masses and molecular mass distributions using sequential, ring-opening polymerization and ring-opening copolymerization methods. These new copolymers represent a diverse platform of resorbable printable materials. Furthermore, these polymers open a previously unexplored range of accessible properties among stereolithographically printable materials, which we demonstrate by printing a polymer with a molecular mass nearly 4 times that of the largest PPF homopolymer previously printed. To further demonstrate the potential of these materials in regenerative medicine, we report the postprinting “click” functionalization of the material using a copper-mediated azide–alkyne cycloaddition. Degradable, Printable Poly(propylene fumarate) Based ABA Triblock Elastomers. Additive manufacturing is rapidly advancing tissue engineering, but the scope of its clinical translation is limited by a lack of materials designed to meet specific mechanical properties and resorption timelines. Materials that are printable via photochemical crosslinking, fully degradable, and elastomeric have proven particularly challenging to develop. Herein, we report the synthesis of a series of poly(propylene fumarate-b-γ-methyl-ε-caprolactone-b-propylene fumarate) ABA triblock polymers using a sequential ring-opening polymerization and ring-opening copolymerization. When crosslinked photochemically using a continuous liquid interface production digital light processing (DLP) Carbon M2 printer, these ABA type triblock copolymers are durable ela (open full item for complete abstract)

Committee: Matthew Becker PhD (Advisor); Dobrynin Andrey PhD (Committee Chair); Wesdemiotis Chrys PhD (Committee Member); Cavicchi Kevin PhD (Committee Member); Willits Rebecca PhD (Committee Member) Subjects: Polymers

Master of Sciences (Engineering), Case Western Reserve University, 2020, Macromolecular Science and Engineering

A novel approach to develop well-defined hyperbranched star polymers is presented herein. The unique three-dimensional structures were synthesized by an arm-first star polymerization route, coupled with an A2 + B3 approach that utilized the copper-catalyzed azide-alkyne cycloaddition (CuAAC). The synthesis of these new materials is relatively straight-forward, and the size of the resultant stars can be easily tuned by varying the reaction conditions. Because the synthesis is tolerant of various different functional groups, there is potential to achieve access to a large library of distinctive star polymers with differing chemical properties. In this vein, the method was used to create stars from polystyrene and polyacrylonitrile starting materials. Moving forward, the unique properties of the materials–highly soluble polymers with both peripheral functional groups and many interior "pockets" offering potential spaces for site isolation– can be used to gain a better understanding of polymer-supported catalysis. Furthermore, it is the hope that these materials are the next step in bridging the gap between the catalytic ability and functional breadth of enzymes as compared to synthetic catalysts.

Committee: Valentin Rodionov (Committee Chair) Subjects: Organic Chemistry; Polymer Chemistry

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2020, Photochemical Sciences

Understanding the facts of decreasing in availability of non-renewable fossil fuels, and increase in demand for new renewable sources, many efforts across the world have been put forward for converting biomass especially carbohydrates and lignin into eco-friendly materials Biomass not only give a greener perspective but also, they are inexpensive; abundant in nature and most importantly they are renewable. By merging the concepts of polymer, organic and photochemistry, one can transform biomass in to photoresponsive materials. The importance and synthesis of biobased polymers, principles of green chemistry and the effects of plastic pollution, were introduced in chapter 1. Inaddition to biobased materials, some fundamental concepts of photochemistry, photoprotecting groups (PPGs), different types of photoinitiators were also included. Second chapter details some of the polymer degradation pathways and their limitations were highlighted. This chapter mainly focus on photoresponsive polymeric/oligomeric materials derived from biomass. The fundamental concepts of phototriggers were utilized in designing and evaluating polymers and degradability at ~ 300nm. Synthesis and characterization of polymers were reported by employing various methods. A detailed photochemical and photophysical studies were carried out to support the mechanism. Chapter three describes about synthesis of novel photoinitiators for visible light mediated polymerization. The novel photoinitiators were evaluated for photopolymerization of acrylate monomers under blue LED irradiation. UV-Vis absorption studies for photoinitiators and gel permeation chromatography analysis for polymers were studied. The strategy developed in this chapter highlights the role of solvent as co-initiator and formation of polymers without photoinitiator leaching. Chapter four details about synthesis and evaluation of biomass derived photoinitiators for type II photopolymerization. In order to understand the nature of (open full item for complete abstract)

Committee: Jayaraman Sivaguru Ph.D (Advisor); Yan Wu Ph.D (Other); Malcolm Forbes Ph.D (Committee Member); Alexander Tarnovsky Ph.D (Committee Member) Subjects: Chemistry; Organic Chemistry; Polymer Chemistry; Polymers

PhD, University of Cincinnati, 2015, Arts and Sciences: Chemistry

This dissertation is mainly based on the works of synthesis and characterization of self-assembling polymers using hydrogen bonding or hydrophobic interactions. Firstly, N-alkyl urea peptoid oligomer was synthesized as backbone of supramolecular polymers through three step repetition cycles with high yield. One N-alkyl urea peptoid precursor was explored to simplify the synthetic process. 4 different functional groups were converted from one precursor. Then 2-ureido-4[1H]-pyrimidinone (UPy) group which is a quadruple hydrogen bonding system was incorporated to N-alkyl urea peptoid oligomers to generate supramolecules. With the experience of UPy unit, we further explored UPy containing monomer to make organogelators. Three different monomers with different Tg values were copolymerized using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Organogels were afforded in both chloroform and dichlorobenzene. Critical gelation concentration and mechanic properties of organogels were examined. Cooperating another novel monomer containing pyrene unit to the above copolymers, fluorescent organogels were achieved which were suitable for potential up-conversion applications. In addition to pyrene, anthracene is another molecule which shows great up-conversion property. A series of Poly[(9-anthrylmethyl methacrylate)-co-(methyl methacrylate)] (Poly(AnMMA-co-MMA)) with different AnMMA ratios were synthesized via RAFT polymerization, resulting in tunable inter-chromophore distances. These polymers can serve as emitters, with PtOEP as sensitizer, in triplet-triplet annihilation up-conversion (TTA-UC) systems. TTA-UC intensity of the Poly(AnMMA-co-MMA)/PtOEP mixtures displays interesting dependence on the AnMMA ratio in the polymer. Interactions between chromophores on the same polymer chain play the key role in affecting the TTA-UC intensity in these systems. It is critical to minimize intra-chain chromophore quenching in order to achieve high UC intensity. H (open full item for complete abstract)

Committee: Neil Ayres Ph.D. (Committee Chair); David Smithrud Ph.D. (Committee Member); Peng Zhang Ph.D. (Committee Member) Subjects: Chemistry

PhD, University of Cincinnati, 2008, Engineering : Materials Science

With the demanding nature of the technology today, scientists are looking for new materials in order to decrease the cost, increase the efficiency of the use of the materials, and decrease time-consuming steps in order to increase the speed of production. New materials are being studied to decrease the weight of cars, planes and space vehicles; surface properties are being modified to decrease the drag coefficient; new technologies are being introduced for speeding up applications in production and assembly lines. In this research we address the needs of different technological applications from a conductivity perspective. In the first part of the thesis, the synthesis of soluble conducting polymers in order to make them more processable for potential electronic and photovoltaic applications is presented. Soluble conducting polymers of 3-hexylthiophene, 3-octylthiophene, 3-decylthiophene and 3-dodecylthiophene were synthesized electrochemically and thus, doped during synthesis. It was found that the conductivities; molecular weights and degrees of polymerization of the polymers strongly depend on the side chain's length. The substitution of alkyl side chains decreases the reactivity of the growing chain, and with an increasing side-chain length, all of these properties show a decrease. The hexyl substituent, being the shortest of the four side chains, causes the least distortion in the background, has the highest conjugation, and has the highest shift in the UV spectrum when it polymerizes. As the length of the side chain increases, the shift in the UV spectrum decreases, too. Decrease in the π-stacking, conjugation and delocalization decreases the conductivity. This gives the material an opportunity to be used in photovoltaic applications. In the second part of the thesis, a conducting adhesive formulation that eliminates the need for heat or other expensive and rather bothersome application methods to activate the adhesive is investigated. Using the quick setting (open full item for complete abstract)

Committee: Stephen Clarson (Advisor); Gregory Beaucage (Committee Member); Jude Iroh (Committee Member); Rodney Roseman (Committee Member) Subjects: Chemical Engineering; Chemistry; Materials Science; Plastics; Polymers

PhD, University of Cincinnati, 2007, Engineering : Materials Science

This work focuses on the use of temperature responsive gels (TRGs) (polymeric hydrogels with a large temperature-dependent change in volume) for flavor retention at cooking temperatures. Specifically, we have studied a gel with a lower critical solution temperature (LCST) that swells at low temperatures and collapses at high temperatures. In the collapsed state, the polymer acts as a transport barrier, keeping the volatile flavors inside. An encapsulation system was designed to utilize the solution (phase separation) behavior of a temperature responsive gel. The gel morphology was understood and diffusive properties were tailored through morphology manipulation. Heterogeneous and homogeneous gels were processed by understanding the effect of temperature on gel morphology. A morphology model was developed linking bulk diffusive properties to molecular morphology. Flavor was encapsulated within the gel and the emulsifying capability was determined. The capsules responded to temperature similarly to the pure polymer. The release kinetcs were compared to commercial gelatin capsules and the temperature responsive polymer took longer to release. Chemistry was developed following guidelines for the Food and Drug Administration for food use. The food grade crosslinking was coupled with commercial scale-up equipment to develop large scale commercial production procedures. This dissertation resulted in a new commercial encapsulation system. The system is able to tailor release kinetics through processing conditions. New crosslinking methods were developed with the possibility of opening new markets in food, flavor, and fragrance.

Committee: Dr. Dale Schaefer (Advisor) Subjects:

Doctor of Philosophy, Case Western Reserve University, 2005, Macromolecular Science

The use of metal-ligand binding as the driving force for the self-assembly polymerizations of a ditopic ligand offers a facile route to the preparation of organic/inorganic hybrid materials. Such metallo-supramolecular polymers potentially offer the functionality of the metal ion along with the processibility of a polymer. This thesis reports the preparation and investigation of a series of metallo-supramolecular polymers prepared from different (macro)monomer units, which consist of flexible alkyl and alkyl ether cores. Attached to either end of these flexible chains is the terdentate ligand 2,6-bis-(benzimidazolyl)-4-oxypyridine. Addition of a metal ion (e.g. Fe(II), Co(II), Zn(II) or Cd(II)), which can bind to the ligand in 1:2 ratio, to a solution of the (macro)monomer results in the self-assembly of linear supramolecular polymers. Viscosity studies demonstrate the formation of self-assembling aggregates and mechanically stable films can be obtained by solution casting these solutions. A series of studies (including DSC, DMA, TGA and WAXD) were carried out in order to examine the solid state properties of films. The metallo-supramolecular polymers which have large poly(tetrahydrofuran) cores form thermoplastic elastomeric films in which the ionic blocks and soft poly(tetrahydrofuran) segments are phase separated. It was also possible to prepare gel-like metallo-supramolecular polymers from one of the monomer units mixed with a lanthanoid metal (e.g. La(III), Eu(III)) and a transition metal ion (e.g. Co(II) or Zn(II)). Such materials show dramatic reversible responses to a variety of stimuli, including thermal, mechanical, chemical and light. The nature of the response can be controlled by the nature of the combination of transition metal ion and lanthanoid metal ion used. These metal-ligand studies influenced the development of ligand-containing cyclic precursors that could be functionalized for reversible cyclization using imine and metathesis chemistry. This l (open full item for complete abstract)

Committee: Stuart Rowan (Advisor) Subjects: Chemistry, Polymer

Doctor of Philosophy, Case Western Reserve University, 1990, Macromolecular Science

Nitrogen containing ladder polymers were synthesized by an intramolecular condensation reaction (deamination) of the corresponding linear prepolymers which have diaminotoluene backbone. The obtained ladder polymers were characterized by 1H NMR, FT-IR, UV-VIS, GPC, EPR and Elemental analysis. Approximately 60% of NH2 groups were consumed by the condensation reaction forming the acridane (secondary amine) and the acridine (tertiary amine) moieties. The more rotation-restricted compound show some degree of condensation as opposed to the less rotation-restricted (more free rotation) compound under the same reaction condition. Condensed ladder polymers have unpaired spins.

Committee: Hatsuo Ishida (Advisor) Subjects: Chemistry, Polymer

Doctor of Philosophy, University of Akron, 2007, Polymer Science

Novel methods for the synthesis of chain-end and in-chain functionalized polymers, as well as star polymers, were developed using anionic polymerization techniques. A new mechanism for the reaction of polymeric organolithium compounds with thiiranes has been found. The reaction of poly(styryl)lithium and poly(butadienyl)lithium with propylene sulfide and ethylene sulfide was investigated in hydrocarbon solution for the preparation of thiol-functional polymers. It was found by MALDI-TOF mass spectral analysis of the reaction products that the reaction proceeded by attack of the anion on the methylene carbon atom of the thiirane ring followed by ring opening to form the thiol-functionalized polymer. The reaction of poly(styryl)lithium with trimethylene sulfide did not produce the corresponding thiol-functionalized polymer; the resulting methyl-terminated polymer was formed by attack of the anion on the sulfur atom followed by ring opening to form a primary carbanion. A new method for synthesis of alkoxysilyl-functionalized polymers was developed. Using a general functionalization methodology based on the hydrosilation of vinyltrimethoxysilane with w-silyl hydride-functionalized polystyrene, alkoxysilyl-functionalized polystyrene was obtained in high yield (83 %). The main side product was vinylsilane-functionalized polymer. A small amount of dimer (approximately 2 %) was formed from the hydrosilation reaction of silyl hydride-functionalized polymer and vinylsilane-functionalized polymer. Star polymers with an average number of 6.8 arms were obtained by reacting poly(styryl)lithium with 6.6 equivalents of vinyldimethylchlorosilane in benzene at 30 C. It was found that, in benzene at 30 C, vinyldimethylchlorosilane is an efficient linking agent for the preparation of well-defined star-branched polymers. In contrast, the reaction of poly(styryl)lithium with 5 equivalents of vinyldimethylchlorosilane in THF at -78 C produced vinylsilane-functionalized polymer in high yiel (open full item for complete abstract)

Committee: Roderic Quirk (Advisor) Subjects: Chemistry, Polymer

Master of Science, The Ohio State University, 1965, Graduate School

Committee: Not Provided (Other) Subjects: