Phase Behavior Of Binary And Polydisperse Suspensions Of Compressible Microgels Controlled By Selective Particle Deswelling, A. Scotti, U. Gasser, E. S. Herman, Jun Han, A. Menzel, L. Andrew Lyon, A. Fernandez-Nieves
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
We investigate the phase behavior of suspensions of poly(N-isopropylacrylamide) (pNIPAM) microgels with either bimodal or polydisperse size distribution. We observe a shift of the fluid-crystal transition to higher concentrations depending on the polydispersity or the fraction of large particles in suspension. Crystallization is observed up to polydispersities as high as 18.5%, and up to a number fraction of large particles of 29% in bidisperse suspensions. The crystal structure is random hexagonal close-packed as in monodisperse pNIPAM microgel suspensions.We explain our experimental results by considering the effect of bound counterions. Above a critical particle concentration, these cause deswelling ...
Multi-Scale Assembly Methodologies Of Poly(3-Hexylthiophene) Derivative Systems For Enhanced Optoelectronic Anisotropy, 2017 California Polytechnic State University - San Luis Obispo
Multi-Scale Assembly Methodologies Of Poly(3-Hexylthiophene) Derivative Systems For Enhanced Optoelectronic Anisotropy, David William Bilger, David William Bilger
Master's Theses and Project Reports
Conjugated polymers represent a class of semi-conducting materials with numerous applications in optoelectronic devices, including organic light-emitting diodes, field-effect transistors, and photovoltaics. Because of the numerous advantages of macromolecular systems, including solution processing and mechanical flexibility, conjugated polymers have become a burgeoning field of research with the hopes of producing cost-effective solution-based electronics. Importantly, optoelectronic device performance is heavily influenced by conjugated polymer backbone orientation and overall thin film morphology. As such, the processing conditions of these systems are important to the construction of high- performance optoelectronics. Polythiophenes are model conjugated polymers that have been studied extensively in halogenated organic ...
Cellulose Reinforced Thermoplastic Composites By In-Situ Ring-Opening Polymerization, 2017 University of Southern Mississippi
Cellulose Reinforced Thermoplastic Composites By In-Situ Ring-Opening Polymerization, Shahab Kashani Rahimi
Over the past two decades, the increasing concern about the negative environmental impacts of synthetic materials has led to rising interests in utilizing renewable natural resources to develop polymer materials with comparable properties and performance to their synthetic counterparts. One of the major fields of interest is polymer composites where the replacement of synthetic fibers with bio renewable natural fibers is of great potential. However, the processing difficulties, in terms of fiber dispersion and thermal stability have limited the application of cellulosic fibers to polymers with low processing temperatures which are mostly hydrophobic polymers. As a result, the true reinforcing ...
Oligo(Ethylene Glycol)-Sidechain Microgels Prepared In Absence Of Cross-Linking Agent: Polymerization, Characterization And Variation Of Particle Deformability, Nicole Welsch, L. Andrew Lyon
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
We present a systematic study of self-cross-linked microgels formed by precipitation polymerization of oligo ethylene glycol methacrylates. The cross-linking density of these microgels and, thus, the network flexibility can be easily tuned through the modulation of the reaction temperature during polymerization. Microgels prepared in absence of any difunctional monomer, i.e. cross-linker, show enhanced deformability and particle spreading on solid surfaces as compared to microgels cross-linked with varying amounts of poly(ethylene glycol diacrylate) (PEG-DA) in addition to self-crosslinking. Particles prepared at low reaction temperatures exhibit the highest degree of spreading due to the lightly cross-linked and flexible polymer network ...
Photopolymerization Synthesis Of Magnetic Nanoparticle Embedded Nanogels For Targeted Biotherapeutic Delivery, 2017 University of South Florida
Photopolymerization Synthesis Of Magnetic Nanoparticle Embedded Nanogels For Targeted Biotherapeutic Delivery, Daniel Jonwal Denmark
Graduate Theses and Dissertations
Conventional therapeutic techniques treat the patient by delivering a biotherapeutic to the entire body rather than the target tissue. In the case of chemotherapy, the biotherapeutic is a drug that kills healthy and diseased cells indiscriminately which can lead to undesirable side effects. With targeted delivery, biotherapeutics can be delivered directly to the diseased tissue significantly reducing exposure to otherwise healthy tissue. Typical composite delivery devices are minimally composed of a stimuli responsive polymer, such as poly(N-isopropylacrylamide), allowing for triggered release when heated beyond approximately 32 °C, and magnetic nanoparticles which enable targeting as well as provide a mechanism ...
Silanol-Assisted Carbinolamine Formation In An Amine-Functionalized Mesoporous Silica Surface: Theoretical Investigation By Fragmentation Methods, Ana P. De Lima Batista, Federico Zahariev, Igor I. Slowing, Ataualpa A. C. Braga, Fernando R. Ornellas, Mark S. Gordon
Igor I. Slowing
The aldol reaction catalyzed by an amine-substituted mesoporous silica nanoparticle (amine-MSN) surface was investigated using a large molecular cluster model (Si392O958C6NH361) combined with the surface integrated molecular orbital/molecular mechanics (SIMOMM) and fragment molecular orbital (FMO) methods. Three distinct pathways for the carbinolamine formation, the first step of the amine-catalyzed aldol reaction, are proposed and investigated in order to elucidate the role of the silanol environment on the catalytic capability of the amine-MSN material. The computational study reveals that the most likely mechanism involves the silanol groups actively participating in the reaction, forming and breaking covalent bonds in the carbinolamine ...
Fabrication And Applications Of Multifunctional Superhydrophobic Surfaces Based On Surface Chemistry And Morphology, 2017 The Graduate Center, City University of New York
Fabrication And Applications Of Multifunctional Superhydrophobic Surfaces Based On Surface Chemistry And Morphology, Yang Liu
All Graduate Works by Year: Dissertations, Theses, and Capstone Projects
Superhydrophobic surfaces are gaining great interests in both fundamental researches and technological applications, because of their unique non-wetting and self-cleaning properties. By mimicking the hierarchical surface structure of the natural superhydrophobic surface, i.e. lotus leaf, numerous artificial surperhydrophobic surfaces were developed. However, the challenge is how to fabricate superhydrophobic surfaces by a scalable and economical method. To address this challenge, our group has developed methodologies that enable the fabrication of superhydrophobic surfaces in inexpensive and potentially scalable ways, such as lamination and 3-D printing. To expand on applications, we also combined other desired functionalities into the superhydrophobic surfaces.
Processing And Characterization Of Nanocomposites Prepared By High Torque Melt Mixing, 2017 Clark Atlanta University
Processing And Characterization Of Nanocomposites Prepared By High Torque Melt Mixing, Lionel W. Cross Jr
Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University
The rapid development of polymer nanocomposites has received extensive attention over the last few decades. The ability to alter functionalities of composites, dramatically improving properties and performance at low filler content creates flexibility in designing materials for advanced applications in various industrial fields. This work focuses on nanocomposites relevant to the packaging and aerospace industries.
This work evaluated the ability to homogeneously distribute nanomaterials into a polymer matrix, understand the effects on rheological properties, understand changes to microstructure and effects, and characterize properties of resulting nanocomposite. High torque melt mixing was used to disperse surface modified cellulose nanocrystals in a ...
Graphene Nanoribbons And Their Polymeric Nanocomposites: Controlled Synthesis, Characterization And Applications, 2017 Pittsburg State University
Graphene Nanoribbons And Their Polymeric Nanocomposites: Controlled Synthesis, Characterization And Applications, Nada M. Aljehany
Electronic Thesis Collection
Carbon based materials are very promising as electrode materials energy generation and storage devices. They have been used for fuel cells, supercapacitors and solar cells. Among the carbon-based materials, graphene is very attractive due to its unique properties such as high electrical conductivity, good mechanical flexibility, large theoretical surface area (2630 m2/g), and high thermal and chemical stability. These unique properties make them very suitable for energy storage applications particularly for supercapacitors. The performance of the graphene as energy storage material could be further improved by growing them in nanoribbon form by unzipping carbon nanotubes. In this thesis ...
Use Of Decahydrodecaborate As Flame Retardants In Polyurethanes, 2017 Pittsburg State University
Use Of Decahydrodecaborate As Flame Retardants In Polyurethanes, Austin W. Bailey
Electronic Thesis Collection
There is a growing need for non-halogenated flame retardants due to the toxicity and environmental impacts that are exhibited by current ones. The polyurethane industry is one that has expressed a need for flame retardants in many of its industrial and commercial applications. For these reasons, two different decaborate compounds, tetramethyl and tetrabutyl ammonium decahydrodecaborate, were synthesized and incorporated into polyurethane films for testing. The compounds were characterized using Fourier Transform Infrared (FT-IR) spectroscopy, Proton-Nuclear Magnetic Resonance (1H-NMR) spectroscopy, Carbon-Nuclear Magnetic Resonance (13C-NMR) spectroscopy, and Boron-Nuclear Magnetic Resonance (11B-NMR) spectroscopy. The compounds were incorporated into a polyol ...
One-Pot Synthesis And Characterization Of A “Click-Able” Polyester Polymer For Potential Biomedical Applications, 2017 Pittsburg State University
One-Pot Synthesis And Characterization Of A “Click-Able” Polyester Polymer For Potential Biomedical Applications, James F. Beach Ii
Electronic Thesis Collection
In this study, a synthetic polyester polymer was designed using polyethylene glycol, sorbitol, glutaric acid and 4-pentynoic acid as monomers. The synthesis was carried out using standard melt polymerization technique and catalyzed by Novozyme-435, an enzyme suitable for polyesterification of biocompatible compounds. The progress of the reaction was monitored with respect to time and vacuum exposure, with samples being subjected to standard characterization protocols. Polymers with high molecular weight and water solubility were chosen for further modification into folate-functionalized polymeric nanoparticles for targeted drug delivery to cancer cells. This was achieved by employing a solvent diffusion method, wherein the polymer ...
Effects Of Processing Parameters On Properties Of Novel Silica-Filled Polysiloxane Materials, 2017 Pittsburg State University
Effects Of Processing Parameters On Properties Of Novel Silica-Filled Polysiloxane Materials, Kyle W. Schwenker
Electronic Thesis Collection
Polysiloxanes are a class of materials that possess high temperature stability and the ability to remain flexible at extremely low temperatures. Their elastomers generally exhibit low strength and have poor mechanical properties unless reinforced with fillers. Reinforcement can be accomplished by compounding reinforcing silica fillers with polysiloxanes via twin-screw extrusion compounding that vigorously mixes the fillers into a polymer matrix. In this thesis, a lab-scale twin-screw extruder was utilized to compound thermoplastic materials to determine the effects of processing on thermoplastics material properties, as well as to determine the extruder’s compounding effectiveness. Processing via lab-scale twin-screw extrusion did not ...
Performance Of Liquid Benzoxazine-Peg Blend Resin Systems For Potential Industrial Composites Processing, 2017 Western Washington University
Performance Of Liquid Benzoxazine-Peg Blend Resin Systems For Potential Industrial Composites Processing, Emily Brown
Graduate Student Conference
The manufacturing of technology and materials based on benzoxazine resin is limited by melt or solvent-based processing in which benzoxazine monomer is either dissolved in a solvent or melted to transfer onto fiberglass or carbon fiber. Solvent based processing depends on the use of organic solvents which impart health and financial risks. Benzoxazine monomer also suffers from high curing temperatures where the benzoxazine polymerizes to form structures with desirable mechanical and thermal properties. Non-flammable liquid benzoxazine resin with low curing temperatures are attractive for their exclusion of organic solvents and ease of processing. In this study three series of blends ...
Design-Structure-Property Relationships Of Purine-Based Copolymers And Chromophores, 2017 University of Tennessee, Knoxville
Design-Structure-Property Relationships Of Purine-Based Copolymers And Chromophores, Graham Smith Collier
Understanding the relationship between monomer design and polymer properties is imperative for developing polymeric systems that can find applicability in targeted technologies. Purines have been extensively studied across many scientific disciplines and are useful due to the diverse properties they possess, which is due in part to the broad scope of precise synthetic transformations that are used to tailor their properties. The overarching goal of my dissertation involves developing the synthesis of “poly(purine)s” and investigating the effect of purine monomer design on polymer properties. In this vein, poly(purine)s and purine-based donor-acceptor small-molecules are synthesized via Stille ...
Effect Of Molecular Structure Of Side Chain Polymers On "Click" Synthesis Of Thermosensitive Molecular Brushes, 2017 University of Tennessee, Knoxville
Effect Of Molecular Structure Of Side Chain Polymers On "Click" Synthesis Of Thermosensitive Molecular Brushes, Christie Maggie Lau
University of Tennessee Honors Thesis Projects
No abstract provided.
Rate Acceleration Of Organocatalytic Ring-Opening Polymerization Rough The Application Of Bis- And Tris- ( Io)Urea H- Bond Donors, 2017 University of Rhode Island
Rate Acceleration Of Organocatalytic Ring-Opening Polymerization Rough The Application Of Bis- And Tris- ( Io)Urea H- Bond Donors, Samuel S. Spink
Senior Honors Projects
Well-defined and functionalized polymers have a wide variety of applications in biomedical studies. Advancements in the fields of drug delivery, microelectronics, and medical imaging, among other applications, are predicated upon the development of methods for the synthesis of precision polymers. Organocatalytic ring-opening polymerization (ROP) of cyclic monomers is an effective route to the production of polymeric materials, namely polyesters and polycarbonates, whose biodegradable properties make them a viable option in biomedical research. Arguably, H-bond mediated catalysts are among the most selective catalysts for ROP, giving rise to highly functionalized polycarbonates, well-controlled polymerizations, and other custom tailored applications. With respect to ...
Silver Nanoparticles As A Potential Solar Absorber, 2017 Bowling Green State University
Silver Nanoparticles As A Potential Solar Absorber, Benjamin Hardy
This work reports the development of Silver nanoparticles implanted into a polymer as a solar absorber. The plasmonic nature of silver nanoparticle allows for adjustments to be made in its UV-VIS-NIR absorbance spectrum. A combination of different sized/shaped particles could result in ideal absorption of the majority of the solar spectrum. Allotting this with the stability of a polymer leads to potential solids or solutions that could work as a solar absorber. Tests were also performed to determine whether or not UV-C irradiation during synthesis effects the characteristics of silver nanoparticles, in particular the absorbance. Successful synthesis of silver ...
Synthesis Of Polythioether Nanoparticles Via Thiol-Alkene/Alkyne Photopolymerization In Miniemulsion, 2017 The University of Southern Mississippi
Synthesis Of Polythioether Nanoparticles Via Thiol-Alkene/Alkyne Photopolymerization In Miniemulsion, Susan E. Walley
Emulsion-based processes – such as miniemulsion polymerizations – provide well-studied synthetic routes to polymer nanomaterials. Miniemulsion polymerizations are characterized as aqueous dispersions of small, narrowly distributed monomer droplets created through high shear and stabilized against Ostwald ripening/collisional degradation by addition of an appropriate surfactant and costabilizer. In this work, thiol–alkene/alkyne photopolymerization in miniemulsion is demonstrated as a simple, rapid, and one-pot synthetic approach to polythioether nanoparticles with tuneable particle size and clickable functionality. Nanoparticles with mean particle diameters ranging from 45 nm to 200 nm were synthesized through simple modifications to the miniemulsion formulation and processing parameters. Facile access ...
Characterization Of Epoxy/Amine Networks With Glycidal Polyhedral Oligomeric Silsesquioxane Surface Modified Silica Nanoparticles, 2017 The University of Southern Mississippi
Characterization Of Epoxy/Amine Networks With Glycidal Polyhedral Oligomeric Silsesquioxane Surface Modified Silica Nanoparticles, Reese K. Sloan
Silica nanoparticles were surface modified with octa-functional glycidal polyhedral oligomeric silsesquioxane (G-POSS) and incorporated into an epoxy/amine system in an effort to increase the mechanical performance of the inorganic/organic hybrid material. The silica nanoparticles were first functionalized with 3-aminoprpyltrimethoxysilane (APTMOS) at 5 and 10 weight percent, and then modified with G-POSS at ratios of 1:10 and 1:5 (APTMOS: G-POSS). The modified particles were then incorporated into an epoxy/amine network consisting of diglycidyl ether of bisphenol A (DGEBA) and aromatic amine, diamine diphenyl sulfone (4,4’ DDS) at 1 and 5 weight percent, resulting in 8 ...
Improving Water Barrier Properties Of Epoxy Coatings With Addition Of Graphene Oxide, 2017 College of William and Mary
Improving Water Barrier Properties Of Epoxy Coatings With Addition Of Graphene Oxide, Sang H. Kim
Undergraduate Honors Theses
Epoxy coating paint is commonly used in metal coatings in aircraft and marine constructions due to its excellent mechanical properties and chemical resistance. However, being in a harsh environment, they are susceptible to degradation by water which significantly reduces the lifetime of the coatings. To better protect the material from corrosion, stress, degradation and absorption of water, nanofillers can be incorporated to improve the barrier properties. This paper explores the effect of incorporating graphene oxide (GO) as a nanofiller and the effect of different functionalization and surface modification of graphene oxide on reducing the water vapor permeability and water absorption ...