Materials Chemistry Commons^™

Curing Of Polymer Thermosets Via Click Reactions, Mark Richard Brei

Dissertations

In the first project, an azide functional resin and tetra propargyl aromatic diamines were fabricated for use as a composite matrix. These systems take already established epoxy/amine matrices and functionalize them with click moieties. This allows lower temperatures to be used in the production of a thermoset part. These new systems yield many better mechanical properties than their epoxy/amine derivatives, but their T_gs are low in comparison.

The second project investigates the characterization of a linear system based off of the above azide functional resin and a difunctional alkyne. Through selectively choosing catalyst the linear system can show …

Synthesis And Characterization Of "Click Inspired" Thiol-Ene-Fullerene Nanocomposites, Amber Danielle Windham

Dissertations

This work explores the covalent incorporation of C₆₀ and Sc₃N@C₈₀ fullerenes into thiol-ene networks by a facile, one-pot photochemical reaction with multifunctional thiol and alkene monomers. Synthesis of disulfide bonds within the tri-functional thiol monomer served to photochemically initiate the reaction when cleaved. This was followed by thermal curing of the pre-polymer for preparation of fullerene-containing thiol-ene films. Films were characterized by standard techniques including infrared spectroscopy, gel percent, and thermogravimetric analysis. The role of C₆₀ and Sc₃N@C₈₀ as suitable alkenes for free-radical reaction with multifunctional thiols was investigated by preparing a …

Hydrogen Bond-Mediated Structural Order In Hydroxylated Bis-Mpa Dendritic Polymers: Experimental And Molecular Dynamics Simulation Study, Maliha N. Syed

Dissertations

Dendritic architectures are echoed throughout nature. While the significance of these pervasive patterns is not entirely clear, connections between their structures and physical properties are fascinating to contemplate. Particular interest has been paid to a family of synthetically manufactured and commercially available dendritic polymers based on 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) as a monomer. Composed of two hydroxyls and a carboxyl group, bis-MPA based structures hydrogen bond (H-bond) profusely. Given the high concentration and unique spatial orientation of end-groups, as well as the multitude of carbonyl, ester, and ether interior H-bond acceptors, a set of distinct H-bond organizations may be observed …

Modern Approaches For Multifunctional Hydrolyzying Thiol-Ene Networks, Nicole Marie Mackey

Dissertations

Marine fouling has been an expensive and time-consuming process for navies and fishermen by the accumulation of marine algae and animals on artificial surfaces. Many coatings have been proposed to combat marine fouling in efforts to extend the lifetime of objects immersed in sea water. However, all coatings tested have either failed to resist fouling for a significant length of time or have released toxins into the environment. We have investigated an environmentally friendly approach to address the problem of marine fouling through the synthesis and preparation of a biocidal and a self-polishing coating. Both novel monomers were prepared containing …

The Investigation Of Asphaltene-Naphithenic Acid And Asphaltene-Surface Interactions, David Tristan Heaps

Dissertations

Asphaltenes represent a ubiquitous problem in the oil industry due to their adverse effects on recovery, production, and processing equipment. These problems have affected oil companies throughout the world, resulting in significant financial losses. In order to expand the existing body of knowledge related to asphaltenes, we have examined how the presence of naphthenic acids contributes to the particle aggregation and sedimentation behavior of asphaltene suspensions as well as how the physics and chemistry of a substrate affect asphaltene adsorption/deposition.

The flocculation of asphaltenes in the presence of naphthenic acids was investigated using dynamic light scattering (DLS), near-infrared spectroscopy (NIR), …

Design, Synthesis, And Polymerization Of Novel Heterocyclic Monomers As Precursors For Functional Polyester, Poly(Ester Amide)S And Polyamides, Eylem Tarkin-Tas

Dissertations

The research presented in this dissertation involves the synthesis and polymerization of heterocyclic monomers which pave the way to biodegradable polyester nanocomposites, functional polyesters or poly(ester amide)s, functional polyamides and supramolecular polymers. The key monomers are ε-caprolactone, γ-acetamido-ε- caprolactone, γ-ethylene ketal-ε-caprolactam and α-amino-ε-caprolactam.

Poly(ε-caprolactone) organo-modified montmorillonite nanocomposites were prepared by in-situ polymerization using dibutyltin dimethoxide as initiator/catalyst. The montmorillonite was first modified with 1-decyl-2-methyl-3-(11-hydroxyundecyl)- imidazolium cation. The hydroxyl functionality was used for not only initiating polymer chains from the surface of the clay platelets but also for grafting polymer chains to the surface by acting as a reversible chain transfer …

Structure-Property Correlation In Cyclopolymerization Of New Acrylate-Based Functional Monomers, Huseyin Tas

Dissertations

New ether dimer; (ED-Od) and (ED-Eh) and diester; (ODE) and (EHDE) derivatives of α-(hydroxymethyl)acrylate, each having two octadecyl and 2-ethylhexyl side chains respectively, and an amine-linked di(2-ethylhexyl)acrylate (AL-Eh), having three 2-ethylhexyl side chains, were synthesized and (co)polymerized to evaluate the effects of differences in the structures of the monomers on final (co)polymer properties, particularly glass transition temperature, Tg. The free radical polymerizations of these monomers yielded high molecular weight polymers. Cyclopolymer formation of ED-Od, ED-Eh and AL-Eh was confirmed by 13C NMR analysis and the cyclization efficiencies were found to be very high (~100%). Copolymers of ED-Od, ODE, ED-Eh, EHDE, …

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 …

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 …

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 …

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 …

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 …

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) …

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, …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …