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 ...
Broadband Measurement Of Rate-Dependent Viscoelasticity At Nanoscale Using Scanning Probe Microscope: Poly(Dimethylsiloxane) Example, Zhonghua Xu, Kyongsoo Kim, Qingze Zou, Pranav Shrotriya
A control approach to achieve nanoscale broadband viscoelasticmeasurement using scanning probe microscope(SPM) is reported. Current SPM-based force measurement is too slow to measure rate-dependent phenomena, and large (temporal) measurement errors can be generated when the sample itself changes rapidly. The recently developed model-less inversion-based iterative control technique is used to eliminate the dynamics and hysteresis effects of the SPM hardware on the measurements, enabling rapid excitation and measurement of rate-dependent material properties. The approach is illustrated by the mechanical characterization of poly(dimethylsiloxane) over a broad frequency range of three orders of magnitude (∼1 Hz to 4.5 KHz).
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 ...
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.
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 ...
Effect Of Chain Rigidity On Network Architecture And Deformation Behavior Of Glassy Polymer Networks, 2017 University of Southern Mississippi
Effect Of Chain Rigidity On Network Architecture And Deformation Behavior Of Glassy Polymer Networks, Kyler Reser Knowles
Processing carbon fiber composite laminates creates molecular-level strains in the thermoset matrix upon curing and cooling which can lead to failures such as geometry deformations, micro-cracking, and other issues. It is known strain creation is attributed to the significant volume and physical state changes undergone by the polymer matrix throughout the curing process, though storage and relaxation of cure-induced strains remain poorly understood. This dissertation establishes two approaches to address the issue. The first establishes testing methods to simultaneously measure key volumetric properties of a carbon fiber composite laminate and its polymer matrix. The second approach considers the rigidity of ...
An Investigation Of The Use Of Cerium And Polyhedral Oligomeric Silsesquioxanes For The Protection Of Polymeric Epoxy Compounds In The Low Earth Orbit Environment, 2017 University of Southern Mississippi
An Investigation Of The Use Of Cerium And Polyhedral Oligomeric Silsesquioxanes For The Protection Of Polymeric Epoxy Compounds In The Low Earth Orbit Environment, Jessica Miriam Piness
Low Earth orbit presents many hazards for composites including atomic oxygen, UV radiation, thermal cycling, micrometeoroids, and high energy protons. Atomic oxygen and vacuum ultraviolet radiation are of concern for space-bound polymeric materials as they degrade the polymers used as matrices for carbon fiber composites, which are used in satellites and space vehicles due to their high strength to weight ratios. Epoxy-amine thermosets comprise a common class of matrix due to processability and good thermal attributes. Polyhedral oligomeric silsesquioxanes (POSS) have shown the ability to reduce erosion in polyimides, polyurethanes, and other polymers when exposed to atomic oxygen. The POSS ...
Impact Of Macromolecular Design On Self-Assembly Properties Of Block Copolymers: Effect Of Tunable Chain Flexibility And Chain Topology, 2017 University of Tennessee, Knoxville
Impact Of Macromolecular Design On Self-Assembly Properties Of Block Copolymers: Effect Of Tunable Chain Flexibility And Chain Topology, Kamlesh Ramesh Bornani
The generation of well-ordered complex structures from constituent block copolymeric building blocks by the spontaneous process of self-assembly is useful in various technologies. The well-defined 3D structures are dictated by complex energetic interplays and their shape is controllable by both preparative conditions and macromolecular design. This dissertation work aims at exploring the effect of chain flexibility and chain topology design changes on phase behavior of block copolymers in solution. Further, we exploit the tunable flexibility of the semiflexible polymers in studying dispersion and controlling macroscale thermal properties in polymer nanocomposites.
The experimental design is based on two model systems: The ...
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 ...
Exploring Thermoresponsive Affinity Agents To Enhance Microdialysis Sampling Efficiency Of Proteins, 2017 University of Arkansas, Fayetteville
Exploring Thermoresponsive Affinity Agents To Enhance Microdialysis Sampling Efficiency Of Proteins, Thaddeus Vasicek
Theses and Dissertations
Affinity agents increase microdialysis protein relative recovery, yet they have not seen widespread use within the microdialysis community due to their additional instrumentation requirements and prohibitive cost. This dissertation describes new affinity agents for microdialysis that require no additional instrumentation to use, have nearly 100% particle recovery, are 7 times more cost efficient than alternatives, and have low specificity enabling their use for a wide variety of proteins. Initially gold nanoparticles were chosen as an affinity ligand support due to their high surface area/volume ratio and colloidal stability. Poly (N-isopropylacrylamide) was immobilized to the gold nanoparticles, which served to ...
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 ...
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 ...