Physical Sciences and Mathematics Commons^™

Molecular Design And Patterning Of Biosurfaces On Poly(Tetrafluoroethylene) (Ptfe), Nattharika Aumsuwan

Dissertations

This dissertation describes the design, synthesis, and development of biocompatible poly(tetrafluoroethylene) (PTFE) surfaces that exhibit anti-microbial, anticoagulant, and dual functional surface properties. It consists of two parts: (1) design, synthesis, and analysis of antimicrobial and anti-coagulant PTFE surfaces, and (2) controllable micropatterning of anti-microbial and anti-coagulant species on the surface. PTFE was modified by Ar microwave plasma reactions in the presence of maleic anhydride, which upon hydrolysis creating COOH groups. These COOH primers were utilized as a platform for further surface reactions to attach polyethylene glycol (PEG) spacers, and penicillin (PEN) or ampicillin (AM) onto the PTFE surfaces. The use …

Nanomaterials From Biologically Active Molecules: Self-Assembly And Molecular Recognition, Min Yu

Dissertations

This dissertation describes the development of molecular assemblies and molecular recognition of phospholipids (PLs) that exhibit potential applications in emerging nanotechnologies. It consists of two parts: (1) structural features of PLs responsible for recognition of synthetic copolymers, and (2) design, synthesis and analysis of magnetic nanotubes obtained from PLs with a common theme of colloidal synthesis served as a platform for film formation and nano-assemblies of nanotubes. Poly(methyl methacrylate/n-butyl acrylate) (p-MMA/nBA) colloidal particles that were stabilized by 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) PLs were synthesized, and upon the particle coalescence, PL stratification resulted in the formation of surface localized ionic clusters (SLICs). These …

Rational Design Of Self-Assembled Nanostructures Based On Polymers Synthesized Via Aqueous Reversible Addition-Fragmentation Chain Transfer Polymerization, Stacey Kirkland York

Dissertations

Recent advances in reversible addition-fragmentation chain transfer (RAFT) polymerization have allowed the rational, bottom-up design of biorelevant assemblies. Utilizing foresight, polymers can be tailored to self-assemble into nano-, micro-, and macroscopic structures. Given the size scale on which rationally-designed polymers can be tailored, they hold significant promise in the biomedical field. For example, nanoscale materials can be designed to carry small-molecule and gene therapeutics while macroscopic structures can be tailored for cell growth scaffolds. The design process begins by selecting monomers, chain transfer agents, and reaction conditions which will yield the desired polymer architecture and composition.

The work herein builds …

Multi Stimuli-Responsive Copolymers Obtained From Colloidal Dispersions, Fang Liu

Dissertations

This dissertation describes the design, synthesis, and development of multi stimuli-responsive random copolymers that exhibit collective responsiveness to temperature, pH or electromagnetic radiation. New colloidal particles of poly(N-(DL)-(1- Hydroxyymethyl) propylmethacrylamide/n-butyl acrylate) (p(DL-HMPMA/nBA) and poly(2-(N,N′-dimethylamino)ethyl methacrylate/n-butyl acrylate) (p(DMAEMA/nBA)) were synthesized, which upon coalesce to form solid continuous films. The presence of lower glass transition (Tg) nBA components not only facilitate film formation, but also provide sufficient free volume for polymer chain rearrangements. These studies showed that coalesced films exhibit 3D dimensional changes upon external stimuli, which are attributed to the collapse and conformational changes of stimuli-responsive components as well as buckling …

Self-Assembly And Gold Nanoparticle Cross-Linking Of Stimuliresponsive Block Copolymers Synthesized Bt Reversible Addition-Fragmentation Chain Transfer Polymerization, Adam Eugene Smith

Dissertations

The ability of amphiphilic block copolymers to self-assemble into various morphologies in aqueous solution in response to specific stimuli has attracted widespread interest for potential applications as targeted drug delivery and diagnostic vehicles. Stimuli-responsive block copolymers afford a facile method for tuning the hydrophilic mass fraction to provide access to various solution morphologies. Reversible additionfragmentation chain transfer (RAFT) polymerization provides the ability to prepare stimuli-responsive block copolymers while maintaining precise control over the macromolecular characteristics (molecular weight, copolymer composition, functionality, etc.) that dictate nanostructure morphology.

This work may be divided into four sections. In the first section the synthesis and …

Synthesis Of Functional Copolymers Via Aqueous Raft Polymerization For Bioconjugation And Targeted Delivery Of Small Interfering Rna, Adam Wesley York

Dissertations

The versatility of reversible addition-fragmentation chain transfer (RAFT) polymerization has moved this controlled radical technique to the forefront of copolymer construction for bioapplications including polymeric drug/gene delivery vehicles. Strengths of the RAFT process include the capacity to control the polymerization of a wide variety of vinyl monomers under mild conditions, its tolerance to numerous chemical groups that allow the preparation of functional copolymers for facile modification, and the range of copolymer architectures with predetermined end group functionalities which may be synthesized. Given these strengths, RAFT polymerization was utilized in this research to synthesize functional/reactive copolymers for bioconjugation and targeted delivery …

Polyisobutylene Chain End Transformations: Block Copolymer Synthesis And Click Chemistry Functionalizations, Andrew Jackson David Magenau

Dissertations

The primary objectives of this research were twofold: (1) development of synthetic procedures for combining quasiliving carbocationic polymerization (QLCCP) of isobutylene (IB) and reversible addition fragmentation chain transfer (RAFT) polymerization for block copolymer synthesis; (2) utilization of efficient, robust, and modular chemistries for facile functionalization of polyisobutylene (PIB). Two site transformation strategies were employed to create block copolymers effectively linking PIB with either poly(methylmethacrylate) (PMMA), polystyrene (PS), and poly(Nisopropylacrylamide) (PNIPAM) block segments. Functionalization of PIB was accomplished by utilizing two click chemistries, the azide-alkyne 1,3-dipolar cyclo addition and the thiol-ene hydrothiolation reaction, and by efficient transformation of the thiol functional …

Aqueous Raft Synthesis Of Stimuli-Responsive, Amphiphilic Block Copolymers And Self-Assembly Behavior In Solution And Incorporation Into Lbl Films, Matthew Grady Kellum

Dissertations

Of all the living radical polymerization techniques, reversible addition– fragmentation chain transfer (RAFT) polymerization is arguably the most versatile in terms of the reaction conditions (e.g. temperature and solvent selection), monomer selection (e.g. neutral, anionic, cationic, and zwitterionic), and purification. Since the introduction of RAFT in 1998, the McCormick research group and others including the Lowe, Sumerlin, and Davis research groups have synthesized a wide range of (co)polymers with predetermined molecular weights, low polydispersities, and advanced architectures utilizing aqueous RAFT (ARAFT) polymerization. These research groups have also studied how various block copolymers exhibit stimuli-responsive behavior due to a change in …

Investigation Of Novel Quasiliving Polyisobutylene Chain-End Functionalization (Quenching) Methods, David Lee Morgan

Dissertations

This volume recounts efforts toward the development and understanding of chain functionalization techniques involving the direct addition of nucleophiles to quasiliving polyisobutylene (PIB). Nucleophiles included in the study were sterically hindered organic bases, (di)sulfides, N-substituted pyrroles, and alkoxybenzenes. A kinetic investigation of the end-quenching of TiCl4-catalyzed quasiliving PIB with sterically hindered amines was used to determine the mode of interaction with TiCl4 and the active species responsible for -proton abstraction. 2,5-disubstituted-N-hydropyrroles formed pyrrole-TiCl3 adducts that were active in formation of exo-olefin chain ends; whereas, with other sterically hindered amines, only an equilibrium fraction of the amine that did not complex …

Synthesis, Characterization, And Deuterium Labeling Of Polyamides Studied By Nuclear Magnetic Resonance Spectroscopy, Christopher Allen Lange

Dissertations

The synthesis, characterization, and deuterium labeling of polyamides have been investigated. In Chapter II, selective deuterium labeling of various polyamides was demonstrated via a facile method which does not require organic solvent or catalyst. Quantitative solution-state NMR analysis showed deuterium incorporation at the carbon alpha to the carbonyl ranged from 20-75%. Incorporation in ε-caprolactam increased with repeated treatments. Isotopic shift effects for the deuterated materials were additive for all sites within experimental error.

In Chapter III, the effect of stoichiometric imbalances on the polymerization of poly(dodecamethylene terephthalamide)was investigated. Molecular weight was varied by polymerizing the monomer salt with excess diaminododecane, …

Structure-Property Relationships In The Formation Of Polyphenylsulfone Molecular Composites And Nanocomposites, Paul Joseph Jones

Dissertations

As the constituent phases in a polymer composite approach the molecular level, specific phenomena occur that can lead to significant changes in material properties when only minimal quantities of the additive are incorporated into the polymer matrix. Molecular composite and nanocomposites are state-of-the-art polymeric materials that contain nanostructured additives effectively dispersed within polymer matrices. The properties of molecular composites and nanocomposites are directly related to the interactions of the nanostructured additive and the polymer matrix. Subtle changes to the nanostructured additive can have profound effects on the ultimate properties of the composite material. Therefore, understanding the structure-property relationships in these …

Investigation Of Network Architecture Development And Properties In Thermoset Matrices, Jeremy Owen Swanson

Dissertations

Matrices employed in composite materials directly influence overall composite properties. In all thermoset materials, molecular level interactions and transformations during cure result in heterogeneous architecture. Variability in connectivity results from the often dramatic spatial and topological changes that occur during the crosslinking process. Compatibility (fillers, pigments, additives), temperature gradients and reactivity differences in the precursors only serve to increase the complexity of network formation. The objective of the research herein is to characterize and understand the relationships between cure conditions, conversion, connectivity, network architecture and properties in glassy thermosetting matrix resins.

In this research, epoxy and vinyl ester resins (VERs) …

Study Of Thermal Frontal Polymerization Utilizing Reactive And Non-Reactive Additives, Veronika Grace Viner

Dissertations

Thermal frontal polymerization is a process that involves a propagating front travelling through a monomer/initiator solution and converting monomer into polymer. The effects of different reactive and non-reactive additives on front temperature, front velocity, and pot life were studied in a thermal frontal polymerization system of multifunctional acrylates. One issue with thermal frontal polymerization of acrylate monomers is the amount of smoke and fumes produced due to high front temperatures. The effect of thermally-expandable microspheres was studied utilizing a variety of monomers. Solid additives including fillers, inert phase changer materials, and high thermal conductive fillers were investigated. The addition of …

Investigation Of Novel Thiol "Click" Reactions, Justin William Chan

Dissertations

The thio-Michael addition reaction is traditionally considered a base catalyzed reaction which involves high catalyst concentrations and long reaction times. This reaction utilizes potent, simple nucleophiles to catalyze the reaction, decreases the catalyst concentration and greatly increases the reaction times. The free radical mediated thiol-ene click reaction uses light or heat and an initiator to catalyze the rapid and quantitative addition of thiols to most electron rich enes without the formation of side products and in the absence of solvent. Recently, the thiol-ene click reaction has been exploited for these reasons in materials science and organic synthesis. The research herein …

Investigation Of The Relationship Between Polymer Structures And Thermal, Mechanical, Viscoelastic Properties, Ethem Kaya

Dissertations

The research presented in this dissertation involves four distinct areas: physical crosslinking systems, UV curable coatings for enhanced oxygen and carbon dioxide barrier properties, synthesis, and investigation of melting behavior/crystallinity relations of linear polyamides with long alkyl chains, and synthesis and characterization of cyclic diamides as precursors to linear polyamides 6 4.

The physical crosslinking section involves synthesis of monomers and polymers bearing cyclodextrin and adamantane pendent groups, and investigation of non-covalent interactions between these polymers (Chapter II). Two methacrylate monomers bearing cyclodextrin and adamantane were synthesized, and copolymerized with poly(ethylene glycol) methyl ether methacrylate. The specific interaction between copolymers …

Random And Block Copolymers Of Poly(Dodecamethyleneterephthalamide), Theodore Frank Novitsky Jr.

Dissertations

The following dissertation focuses on the synthesis and characterization of poly(dodecamethylene terephthalamide) (PA-12,T) and novel copolymers. Chapter I details the synthesis of PA-12,T homopolymer by melt condensation polymerization. A series of homopolymers with different molecular weights were obtained by adjusting the stoichiometry of the polymerization using 1,12-diaminododecane, terephthalic acid and benzoic acid. End group 13C NMR spectroscopy resonances were obtained by correlating peak intensities with intrinsic viscosity values. From the NMR data, total end group concentrations and molecular weights were determined for each sample. The data exhibited a linear trend when plotting log (IV) versus log (Mn), and previously unknown …

Preparation And Characterization Of Thiol Based Polymeric Materials, Junghwan Shin

Dissertations

The thiol click-type reaction is one of the most efficient chemical processes that can undergo at room temperature in the benign organic solvent providing excellent opportunity in the fabrication of new materials as well as development of new manufacturing processes. Moreover, the versatility of thiol click-type reactions with many different functional groups such as ene, yne, epoxy, isocyanate, and alkyl halide is the important aspect that should be differentiated from the classic azide-alkyne click chemistry. Although, there are tremendous studies on many areas using thiol click-type reactions, the efficiency and utilities for the material applications have been barely explored. Especially, …

Raft Synthesis Of Water-Soluble, Stimuli-Responsive (Co)Polymers And Post-Polymerization End Group Modification Via The Thiol-Ene Reaction, Bing Yu

Dissertations

A series of water-soluble, stimuli-responsive (co)polymers was synthesized via the reversible addition-fragmentation chain transfer (RAFT) polymerization. The end group of a RAFT polymer, poly(jV-isopropylacrylamide), was modified to ene or yne function via thiol-ene click chemistry. The ene or yne end group subsequently underwent thiol-ene or thiol-yne addition affording mono- or di-functional end group. First, three methacrylic monomers containing 2 or 3 pendent tertiary amine functional groups, l,3-bis(dimethylamino)propan-2-yl methacrylate (Ml), l-(bis(3-(dimethylamino)propyl)amino)propan-2-yl methacrylate (M2), and 2-((2-(2-(dimethylamino)ethoxy)ethyl)methylamino)ethyl acrylate (M3), were synthesized via an acylation reaction between methacryloyl chloride and the corresponding aminoalcohol. All of these three monomers were successfully homopolymerized under RAFT conditions …

Design, Synthesis, And Film Formation Of Fluorine Containing Colloidal Dispersions, Anuradha Misra

Dissertations

Fluoropolymers (FPs) have been subject of interest for many years, however due to extreme synthetic and processing conditions their applications have been limited. This dissertation focuses on design and synthesis of fluorine containing colloidal dispersions to advance limited knowledge and to gain further understanding of fluorine containing colloidal dispersions. Fluoroacrylates and fluoro methacrylates consisting of varying chain length of perfluoroalkyl side chain were copolymerized with methylmethacrylate (MMA) and n-butylacrylate (n-BA) under aqueous environment utilizing phospholipids (PLs) as dispersing agent. Morphologies of colloids, coalescence, and film formation processes after water evaporation was investigated using various microscopic probes such as transmission electron …

Magnetic And Dielectric Properties Of Sulfonated (S) Poly[(Styrene)-(Ethylene-Co-Butylene)-(Styrene)] (Sebs) Block Copolymer/Magnetic Metal Oxide Nanocomposites Synthesized Via An In-Situ Precipitation Method, Sateesh Kumar Peddini

Dissertations

Block copolymer/magnetic metal oxide nanocomposites were synthesized by growing metal oxide nanoparticles (cobalt ferrite, CoFe204 and iron oxide, a-Fe203) in sulfonated (s) poly (styrene) (PS) block domains of sulfonated poly [(styrene)-(ethyleneco- butylene)-(styrene)] (SEBS) BCP preformed films via an in-situ precipitation method by dissolving the salts of respective metal chloride (s) in a suitable solvent that selectively swells the sPS regions. Inorganic uptake was determined using thermogravimetric analysis (TGA), and it was observed that none of the samples incorporated more than 5 wt % of the inorganic component. Dynamical mechanical analysis was used to observe the changes in the glass transition …

Influence Of Functional Components On The Film Formation Of Colloidal Dispersions, Kevin Lee Rhudy

Dissertations

A number of colloidal dispersions were synthesized to advance knowledge and gain understanding regarding interactions between individual components and for elucidation of complex processes governing their film formation. These studies show that for methyl methacrylate/n-butyl acrylate (MMA/nBA) colloidal dispersions, the presence of functional components significantly affects film formation. The incorporation of polyvinyl alcohol (PVOH) into pMMA/nBA colloidal dispersions creates competing environments between the copolymer particle surfaces, aqueous phases, and dispersing agents which results in migration with self-induced stratification occuring during coalescence. pMMA/nBA/PVOH films stratify to form sodium dodecyl sulfate (SDS) rich film-air (F-A) interfaces, and the -SO3" moieties exhibit preferential …

Investigation Of The Interactions Of Cationic Polyelectrolytes With Anionic Surfactants: Effects Of Polymer, Surfactant And Solution Properties, Lisa Renee Huisinga

Dissertations

The intent of this research is to explore and understand the effects that a range of polymer, surfactant and solution parameters have on the interaction of oppositely-charged polymers and surfactants. Cationic polysaccharides were chosen for this research because they are known to interact with anionic surfactants, and they offer a wide range of adjustable polymer properties, including molecular weight, charge substitution, and backbone structure. Cationic poly(vinylpyridinium hydrochloride) polymers were chosen for these studies because they provide the opportunity to explore the effects of charge position on the interaction of cationic polymers with anionic surfactants and how this influences the mechanism …

Examination Of An Aloe Vera Galacturonate Polysaccharide Capable Of In Situ Gelation For The Controlled Release Of Protein Therapeutics, Shawn David Mcconaughy

Dissertations

A therapeutic delivery platform has been investigated with the ultimate goal of designing a sustained protein release matrix utilizing an in-situ gelling, acidic polysaccharide derived from the Aloe vera plant. The Aloe vera polysaccharide (AvP) has been examined in order to determine how chemical composition, structure, molecular weight and solution behavior affect gelation and protein/peptide delivery. Correlations are drawn between structural characteristics and solution behavior in order to determine the impact of polymer conformation and solvation on gel formation under conditions designed to simulate nasal applications. Steady state and dynamic rheology, classic and dynamic light scattering, zeta potential, pulse field …

Dispersion States And Surface Characteristics Of Physically Blended Polyhedral Oligomeric Silsesquioxane/Polymer Hybrid Nanocomposites, Rahul Misra

Dissertations

Control of dispersion and segregation states of nanostructured additives is one of the biggest challenges in realizing the optimum potential of high-performance hybrid polymer nanocomposites. Polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals, with their hybrid organic-inorganic nature and flexible functionalization with a variety of organic substituents, yield possibilities to control dispersion and tune compatibility in a wide range of polymer systems. The overall goal of this research is to investigate the fundamental parameters that influence the dispersion and segregation states of POSS nanostructured chemicals and to understand chain dynamics and conformations in physically blended POSS hybrid polymer nanocomposites (HPNC's). Multiple structural …

Synthesis, Propagation Kinetics, And Characterization Of D,L-Lactide-Based Polyols And Polyurethanes Therefrom, Scott Joseph Moravek

Dissertations

In order to expand the usefulness of degradable polyesters, degradable polyurethanes were synthesized using a mixed polyol system including poly(D,L-lactideco- glycolide) (PLGA), a well-known degradable polyester. Two isocyanate systems, methyl 2,6-diisocyantocaproate (LDI) and dicyclohexylmethane-4,4'- diisocyanate(Hi2MDI), were studied in order to achieve optimal physical and thermal properties of the thermoplastic polyurethane (TPU) while maintaining degradablity. The LDI based systems had excellent physical properties as well as thermal properties that may make them suitable for biomedical devices. The H12MDI based TPUs also had excellent physical properties as well as a higher melting temperature. The aforementioned TPUs were synthesized in small batches. Another …

Photopolymerization And Characterization Of Thiol-Enes And Thiourethanes, Qin Li

Dissertations

Compared to conventional acrylic monomer systems, thiol-ene photopolymerization, an efficient click process leading to the formation of dense and uniform molecular networks, has several distinct advantages including relative insensitivity to oxygen inhibition, high monomer conversion and low shrinkage. Although there has been a revival of interest in thiol-enes in the past 6 years, the structure-property relationship of these networks has not been explored in detail. For future applications, thiol-enes with higher shelf-life stability and glass transition temperatures need to be used. Sulfur containing urethanes, thiourethanes and dithiourethanes are a class of widely used materials due to their distinct properties such …

The Relationship Betweeen Dynamic And Chemical Factors On The Morphology In Aot-Water-Polymer Systems, Jolanta Elzbieta Marszalek

Dissertations

Photopolymerization of reverse microemulsion demonstrates strong influences from dynamical and chemical factors on morphology of formed polymer systems. Upon polymerization the clear microemulsion with nanoscale structures transforms into opaque films with larger aggregates that scatter light. Studied here were microemulsions based on acrylate and on thiol-ene chemistries. The difference in the two reaction mechanisms results in the phase separation occurring at different stages of the material formation. Consequently, the morphology of the material demonstrates distinct dissimilarities in the two systems. In addition, the chemical structure of the monomers promotes these morphological differences. When the microemulsion is composed of acrylate and …

Preparation Of Carboxylic Acid Functionalized Glycopolymers Through Raft And Post-Polymerization Modification For Biomedical Application, Husnu Alp Alidedeoglu

Dissertations

The primary theme of this dissertation involves the synthesis of well-defined primary amine functionalized polymers, subsequent modification of the polymers to produce novel carboxylic acid functionalized glycopolymers and surface polymerization of these systems utilizing controlled polymerization techniques. Additionally, the synthesis of new water-based allylic copolymer latexes is described. Carbohydrates are natural polymers which possess unlimited structural variations. They carry a huge density of information, and play major roles in recognition events and complex biological operations. For example, hyaluronic acid (HA), an anionic glycosaminoglycan, provides lubricating and cushioning properties in the extracellular matrix and has been found to be involved in …

Synthesis And Characterization Of Polymeric Materials Derived From Multifunctional Alkyl A-Hydroxymethylacrylates, Jean-Francois Morizur

Dissertations

The research presented in this dissertation covers the investigation of new materials derived from alkyl a-hydroxymethylacrylates (RHMA). The first project exposed in Chapter II involves the synthesis, characterization of RHMA-based reactive surfactants and their successful incorporation in acrylic latexes. The amphiphilic monomers testify of a good copolymerization behavior with other acrylic monomers such as methyl methacrylate and butyl acrylate although their extensive bulkiness. They led to the formation of well-defined polymeric particles via a seeded emulsion polymerization process and permitted decreasing significantly the water sensitivity of the resulting films as compared to film incorporating conventional emulsifier such as sodium dodecyl …

Broadband Dielectric Spectroscopy Studies Of Nafion, David Walter Rhoades

Dissertations

In light of available literature regarding Nafion® materials, it is apparent that an information gap exists between the current state of understanding of Nafion relaxations and the dielectric behavior of these materials. Although the currently available dielectric relaxation data is accurate it is very limited in its scope—specifically in-depth broadband analyses are not available. As a result, very little information is available regarding the dependence of the relaxation processes on frequency and temperature. This presents an important opportunity for the exploration of the dielectric broadband relaxation behavior of Nafion® materials. The primary intent of this research is to quantify the …