Polymer Chemistry Commons^™

Development Of Quantitative Ft- Ir Methods For Analyzing The Cure Kinetics Of Epoxy Resins, Sang Ha Son

Open Access Dissertations

Epoxy thermosets are important engineering materials with applications in coating, adhesives, packaging and as structural components in a variety of advanced engineering products. The ultimate performance of polymer critically depends upon the details of the cure chemistry used to produce the thermoset. In order to better understand and monitor the cure chemistry, quantitative analysis of the FT-IR response has been developed for describing the epoxy-amine curing reaction as well as monitoring the hydrogen bonding that occurs in these systems The FT-IR analysis includes (i) quantitative deconvolution of complex peaks into individual spectral contributions, (ii) peak identification via DFT analysis and …

The Effect Of Composition On The Linear And Nonlinear Mechanical Properties Of Particulate Filled Elastomers, Oluwaseyi Ogebule

Open Access Dissertations

Engineering elastomers are materials capable of undergoing large deformation upon load application and recovering upon load removal. From car tires to building vibration isolator systems, elastomers are the most versatile of engineering materials. The inclusion of particulate fillers into elastomers enhances their mechanical properties (modulus, tensile strength, toughness, tear resistance, etc) thereby extending their applicability to more demanding functions. The automotive, healthcare, construction, adhesives and consumer products are some of the many industries that produce finished goods containing elastomeric parts.

Despite the various concepts on reinforcement in filled elastomers, a complete understanding of their linear viscoelastic properties and the nonlinear …

Use Of Thermodynamic Models For Optimizing Fuel Treatment Processes, Shawn Pj Kirby, Andrew Guenthner

STAR Program Research Presentations

Dyes are often added to fuels for tax purposes, but they cause degradation of the fuels. It would be advantageous to remove the dyes prior to their use in critical aerospace applications. Current technologies vary in the efficiency with which they can remove unwanted dyes from fuel sources. We have used Hansen Solubility Parameters to develop an “ideal solvent” that can be used to extract these dyes from fuel. This will also be applied to removal of sulfur compounds from fuels. Sulfur compounds in fuels create sulfates during combustion, which in turn react with water to make sulfuric acid. Sulfuric …

Development Of Colloid Displacement Lithography Platforms For Sensor Applications, Mahesh Thugu

Masters Theses & Specialist Projects

In this work, Poly (diallyldimethylammonium) chloride - (PDDA) was used as a base layer for developing colloid displacement lithography platforms for sensor applications. Previous work shows that glass coated with PDDA and exposed to gold acts as a good platform for colloid displacement lithography. However, for actual sensor applications, electrical isolation of individual sensor sections must be achieved. This is attempted by laying down a 40 μm stripe of PDDA on a cleaned substrate and coating that stripe with gold colloid. The size of 40 μm or less in width is set as the target to fit within the scan …

In Situ Quenching And Post-Polymerization Modification Of Telechelic Polyisobutylene, Todd Raymond Hartlage

Dissertations

Polyisobutylene (PIB) is a saturated hydrocarbon elastomer that can only be produced by cationic polymerization. The water-initiated, chain transfer controlled synthesis conducted on an industrial scale produces monofunctional PIB with mixed olefin end groups. Living cationic techniques produce mono- and di-functional telechelic PIB. In situ quenching is the process of adding functional molecules to the polymerization reactor after all monomer is consumed. These quencher species bond to the chain ends, installing their latent functionality onto the polymer chain. To date, all quenchers utilized have been soft π-nucleophiles.

In the first project, free thiols, both aromatic and aliphatic, are shown to …

Relation Between The Adsorption Behavior And Bulk Complexation In Oppositely Charged Polyelectrolyte-Surfactant Systems: Effect Of Polyelectrolyte Concentration, Molecular Weight, Charge Localization And Backbone Rigidity/Hydrophobicity, Vipul Suhas Padman

Dissertations

Due to a wide range of applications, much emphasis has been placed on understanding the physicochemical behavior of polyelectrolyte/surfactant complexes, both at air-water interface and in the bulk. However, the correlation between the adsorption behavior and complexation in the bulk is less explored. In this research, this correlation is investigated and its dependence on polyelectrolyte concentration, molecular weight, charge localization and backbone rigidity and hydrophobicity is studied. The polyelectrolyte concentration is normalized with respect to it critical overlap concentration in order to compare the polymer in same concentration regime. Different polyelectrolyte systems were used to analyze the polyelectrolyte structural effect: …

Synthesis And Characterization Of Polyisobutylene-Block-Polyamides As Novel Thermoplastic Elastomers, Lauren Renee Kucera

Dissertations

Academic research has focused on two main areas of the living carbocationic polymerization (LCP) of isobutylene (IB): (1) the in-depth study and understanding of mechanistic features of the polymerization, and (2) the utilization and manipulation of the unique aspects of PIB in order to produce practically useful polymeric materials. The research included in this dissertation focuses mainly on the latter objective. This work details three main areas of research: (1) the copolymerization of PIB and polyamides (PA) to form novel thermoplastic elastsomers (TPEs), (2) the mechanical, physical and thermal properties of the novel PIB-PA materials, and (3) the use of …

Improving The Stability Of High And Low Bandgap Polymers Organic Photovoltaic Devices Using A Solution Based Titanium Sub-Oxide Interfacial Layer, Kurniawan Foe

Electrical & Computer Engineering Theses & Dissertations

The improvement in device efficiency has brought organic photovoltaic (OPV) devices closer to commercial viability, highlighting the importance of studying the lifetime and stability of OPV devices. At present, the lifetime and stability of OPV devices is much shorter and poor mainly caused by oxygen, moisture, and light resulting in the oxidation on low work function electrodes and the degradation of the morphology of the photoactive layer. To improve the lifetime and stability of the OPV devices, we used newly developed low bandgap polymer, PCDTBT, as the electron acceptor material and a solution based titanium sub-oxide (TiOx) interfacial layer inserted …

Latent Cysteine Residues From Polymers Prepared Via Free And Controlled Radical Polymerizations, Douglas Vincent Amato

Master's Theses

One less commonly used “click” reaction is thiazolidine chemistry. Thiazolidine chemistry is a commonly used reaction used in biological systems because the reaction requires the presence of both cysteine (a common amino acid) and an aldehyde or ketone. If cysteine residues could be incorporated into a polymer then a variety of applications could be developed. Polymers containing free thiols (aka thiomers) have developed in the last decade to become great mucoadhesives. If there was a facile route to control the amount of free thiols along the polymer then more fine-tuned and potentially stronger adhesives could be made. For these reasons …

Label-Free Detection Of Low Protein Concentration In Solution Using A Novel Colorimetric Assay, Molla R. Islam, Michael J. Serpe

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Dual pH and temperature sensitive microgel-based etalons were fabricated by sandwiching a “monolithic” microgel layer between two semitransparent, Au layers. The devices exhibit visual color and multipeak reflectance spectra, both of which primarily depend on the distance between the Au surfaces mediated by the microgel diameter. We found that a polycationic polyelectrolyte can penetrate through the Au overlayer to interact with negatively charged microgel confined between Au overlayers. In this submission we report that biotinylated polycationic polymer can penetrate through the Au overlayer of a poly (N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgel-based etalon and cause the microgel layer to collapse. The collapse …

Fused Arenes-Based Molecular And Polymeric Materials For Organic Field Effect Transistors, Harista Irugulapati

Masters Theses & Specialist Projects

In the past decade, tremendous progress has been made in organic field effect
transistors. Fused oligothiophenes and anthracene molecules are fascinating
macromolecules having unique optoelectronic properties. These compounds are successfully employed as active components in optoelectronic devices including field effect transistors. Our goal is to design and synthesize conjugated molecular materials, which are highly functionalized through structural modifications in order to enhance their electronic, photonic, and morphological properties. The main desire is to synthesize novel organic fused-arenes having efficient charge carrier mobilities, as well as to optimize optical properties for organic field effect transistors (OFETs). Novel series of fused arene …

Direct Chain-End Functionalization Of Living Polyisobutylene With Phenoxyalkyl(Meth)Acrylates, Conor Patrick Roche

Master's Theses

This volume describes efforts toward the synthesis and employment of phenoxyalkyl (meth)acrylates, which were used to end-quench 1sobutylene polymers m1tiated from 2-chloro-2,4,4-tnmethylpentane (TMPCl), and 5-tert-butyl-1 ,3-d1(1-chlorol- methylethyl)benzene (bDCC), respectively, at -70 °C in 40/60 (v/v) hexane/methyl chlonde. The quencher/cham end molar rat10s typically ranged from 2.5-4, while the ratio of Lewis ac1d/cham end was vaned from approximately 3 5-6 In all cases, alkylation occurred exclusively at the para position of the quencher and no cham degradat10n was observed, even at high concentrations of TiC14 and long reaction times. Prellmmary qualitative studies mvolved the reaction of quenchers of varymg alkyl tether …

Photopolymerization And Characterization Of Modified Thiol-Ene Networks, Bradley James Sparks

Dissertations

Photopolymerization provides a unique ability to control variables typically uncontrollable using traditional thermally initiated polymerization, thus leading to its use in a broad range of commercial operations. Many of the traditional photopolymers suffer from several setbacks, including oxygen inhibition, unwanted stress buildup which leads to bulk shrinkage, etc., which ultimately lead to diminished polymer performance. The photopolymerization of multifunctional thiols and alkenes has been shown to provide a means to improve upon the weaknesses of traditional photoinitiated polymerizations. The free radical polymerization of thiol and –ene monomers occurs via a series of free radical chain transfer events, as a result, …

Dynamic Bioactive Stimuli-Responsive Polymeric Surfaces, Heather Marie Pearson

Dissertations

This dissertation focuses on the design, synthesis, and development of antimicrobial and anticoagulant surfaces of polyethylene (PE), polypropylene (PP), and poly(tetrafluoroethylene) (PTFE) polymers. Aliphatic polymeric surfaces of PE and PP polymers functionalized using click chemistry reactions by the attachment of –COOH groups via microwave plasma reactions followed by functionalization with alkyne moieties. Azide containing ampicillin (AMP) was synthesized and subsequently clicked into the alkyne prepared PE and PP surfaces. Compared to non-functionalized PP and PE surfaces, the AMP clicked surfaces exhibited substantially enhanced antimicrobial activity against Staphylococcus aureus bacteria. To expand the biocompatibility of polymeric surface …

Biological And Biologically Inspired Polymers For Interface Modification, Lea Clayton Paslay

Dissertations

Naturally occurring macromolecules are produced for a specific function and have the selectivity to accomplish objectives with little waste in energy. The scientific community strives to develop smart, efficient molecules on an economical scale, thus lessons can be learned from nature and applied to cost effective synthetic systems. First, the mimicry of naturally occurring antimicrobial peptides (AMPs) will be described. AMPs show great potential as alternatives to conventional antibiotics as they can selectively bind and eliminate pathogenic bacteria without harming eukaryotic tissues. Aqueous reversible addition–fragmentation chain transfer (RAFT) polymerization was utilized to prepare primary and tertiary amine containing AMP polymer …

Investigations Toward Tunability Of Mechanical, Thermal, And Impact Properties Of Thiol-Ene Networks For Novel High Energy Absorbing Materials, Olivia Devon Mcnair

Dissertations

The UV polymerization of thiols with electron rich alkenes is a highly resourceful reaction that has been utilized by scientists within various disciplines to produce an even more versatile display of applications. This dissertation focuses on a newer application, thiol-ene network (TEN) materials for energy absorption devices. TEN networks display a host of positive polymer properties such as low stress, high optical clarity and uniformity, but they also suffer from unfavorable mechanical properties such as low toughness and elongation at break. The poor mechanical properties demonstrated by TENs prohibit them as choice materials for applications requiring thicker material forms, including …

Synthesis Of Polyhedral Oligomeric Silsesquioxane (Poss) Functionalized Carbon Nanotubes For Improved Dispersion In Polyurethane Films, Xiaonan Kou

Dissertations

Carbon nanotube (CNT) polymer nanocomposites are promising advanced materials. These materials exhibit the advantages of traditional polymeric materials, such as being light weight and easy to process, combined with the potential to exhibit enhanced mechanical, thermal and electrical properties compared to pure polymers. To achieve substantial improvement of composite properties at low CNT loading, uniform dispersion of CNTs in the polymer matrix and strong CNT-polymer interfacial interaction are needed. However, it is difficult to achieve adequate dispersion and interfacial interactions due to the inert nature of CNTs. In this project, polyhedral oligomeric silsequioxane (POSS) will be used as a dispersing …

Nanoparticle Filled Polymeric Systems For Gas Barrier And Flame Retardant Properties, Yingji Wu

Dissertations

Polymer composite gas barrier and fire retardant properties were studied in this investigation. An increase in the gas barrier property was observed by adding silicate nanotubes or clay nanoparticles into polymeric systems. Oxygen permeability, diffusivity, solubility and water vapor permeability were determined for polyimide/silicate nanocomposites with 0 to 9.99% (vol/vol) filler loading. Both oxygen and water vapor permeability for the system gradually decreased when adding increasing amounts of nanofiller up to 4.50% (vol/vol) and increase again after that. The permeability decrease was caused by both the diffusivity and solubility coefficient changes, although diffusivity (the tortuous factor) is the main reason …

Relationships Between Cure Kinetics, Network Architecture, And Fluid Sensitivity In Glassy Epoxies, Katherine Lea Frank

Dissertations

Relationships between chemical structure, cure kinetics, network morphology and free volume have been correlated with fluid ingress for glassy epoxy network blends. Polymers synthesized from diglycidyl ether of bisphenol-A (DGEBA) and diglycidyl ether of bisphenol-F (DGEBF) were blended with varying amounts of triglycidyl-m-aminophenol (TGAP), tetraglycidyl-4,4-diaminodiphenylmethane (TGMP), napthylamine (NA), adamantylamine (AA), and aminopropylisobutyl polyhedral oliogmericsilsesquioxane (AI-POSS) and cured with 3,3’- and 4,4’- diaminodiphenylsulfone (DDS) to control fractional free volume, average hole size and morphology.

Varying curing profiles introduced morphological changes resulting in differences in network architectures. Epoxy with 10% NA had a smaller V_h (71 ų) …

Utilizing Polymer Topology In Peptide-Based Block Copolymers: Unique Aqueous Assembly And Responsive Behavior, Jacob Griffin Ray

Dissertations

This document details work in the area of amphiphilic polypeptide-based block copolymers that are able to self-assemble into well-defined nanostructures in aqueous solution. The main focus of this work is to understand the impacts of polymer topology on self-assembly behavior and response to external stimulus, particularly pH. Poly(L-lysine) and poly(L-glutamic acid) are two pH-responsive, hydrophilic polypeptides that possess the unique property of undergoing α-helix to random coil secondary structure transitions with pH, and this responsiveness can lead to global morphology changes such as changes in aggregate size or even morphology transitions. These polypeptides are synthesized via ring opening polymerization of …