Polymer Chemistry Commons^™

Responsive Nanogel Probe For Ratiometric Fluorescent Sensing Of Ph And Strain In Hydrogels, Mingning Zhu, Dongdong Lu, Shanglin Wu, Qing Lian, Wenkai Wang, Amir H. Milani, Zhengxing Cui, Nam T. Nguyen, Mu Chen, L. Andrew Lyon, Daman J. Adlam, Anthony J. Freemont, Judith A. Hoyland, Brian R. Saunders

Engineering Faculty Articles and Research

In this study a new pH-responsive nanogel probe containing a complementary nonradiative resonance energy transfer (NRET) fluorophore pair is investigated and its ability to act as a versatile probe of network-related changes in three hydrogels demonstrated. Fluorescent sensing using NRET is a powerful method for studying relationships between Angstrom length-scale structure and macroscopic properties of soft matter. Unfortunately, inclusion of NRET fluorophores into such materials requires material-specific chemistry. Here, low concentrations of preformed nanogel probes were included into hydrogel hosts. Ratiometric photoluminescence (PL) data for the gels labeled with the nanogel probes enabled pH-triggered swelling and deswelling to be studied …

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 of the largest …

Cellulose Reinforced Thermoplastic Composites By In-Situ Ring-Opening Polymerization, Shahab Kashani Rahimi

Dissertations

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 …

Multi-Scale Assembly Methodologies Of Poly(3-Hexylthiophene) Derivative Systems For Enhanced Optoelectronic Anisotropy, David William Bilger

Master's Theses

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 …

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. Moreover, AFM …

Photopolymerization Synthesis Of Magnetic Nanoparticle Embedded Nanogels For Targeted Biotherapeutic Delivery, Daniel Jonwal Denmark

USF Tampa 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 for …

Fabrication And Applications Of Multifunctional Superhydrophobic Surfaces Based On Surface Chemistry And Morphology, Yang Liu

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.

The transparent …

Development Of A Humidity-Resistant Coating To Impart High Oxygen Barrier Performance To Food Packaging Films, Ryan Yinghua Cox

Master's Theses

Oxygen barrier coatings have the potential to greatly extend the lifetime of certain food products by incorporating them into existing food packaging. Present technologies face definite challenges of maintaining high performance, while attaining simple and inexpensive preparation methods. The oxygen barrier effect obtained with these coatings is also susceptible to a plasticization effect when exposed to high humidity, since water vapor molecules are readily soluble in typically hydrophilic resins. In this work, we demonstrate a 1 – 2 micron thick oxygen barrier coating, prepared on a 12 micron poly(ethylene terephthalate) substrate, that has oxygen transmission rates as low as 1.44 …

A Comparison Study Of Two Synthesis Methods For Polymer Of Intrinsic Microporosity 1 (Pim-1), Conor S. Perry

Materials Engineering

Polymers of Intrinsic Microporosity (PIMs) are an emerging polymeric material class for molecular sieving applications. This study focuses on PIM-1, an alternating copolymer of 5,5’,6,6’-tetrahydroxy-3,3’,3,3’-tetramethyl-1,1’-spirobisindane and tetrafluoroterephthalonitrile synthesized via nucleophilic aromatic substitution. PIM-1 been widely studied as a gas separating material and filtering membrane, but in this case, it is studied as a battery separator material. PIM-1’s microporous (pore diameters less than 2 nm) structure allows smaller favorable ions to transport while preventing larger ions and compounds from transporting. Two synthesis methods, round bottom flask synthesis and ball mill synthesis, of PIM-1 are compared to see any improved characteristics. The …

Application Of Bottlebrush Block Copolymers As Photonic Crystals, Allegra L. Liberman-Martin, Crystal K. Chu, Robert H. Grubbs

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Brush block copolymers are a class of comb polymers that feature polymeric side chains densely grafted to a linear backbone. These polymers display interesting properties due to their dense functionality, low entanglement, and ability to rapidly self-assemble to highly ordered nanostructures. The ability to prepare brush polymers with precise structures has been enabled by advancements in controlled polymerization techniques. This Feature Article highlights the development of brush block copolymers as photonic crystals that can reflect visible to near-infrared wavelengths of light. Fabrication of these materials relies on polymer self-assembly processes to achieve nanoscale ordering, which allows for the rapid preparation …

Microwave-Assisted Topochemical Manipulation Of Layered Oxide Perovskites: From Inorganic Layered Oxides To Inorganic-Organic Hybrid Perovskites And Functionalized Metal-Oxide Nanosheets, Sara Akbarian-Tefaghi

LSU New Orleans Theses and Dissertations

Developing new materials with desired properties is a vital component of emerging technologies. Functional hybrid compounds make an important class of advanced materials that let us synergistically utilize the key features of the organic and inorganic counterparts in a single composite, providing a very strong tool to develop new materials with ”engineered” properties. The research presented here, summarizes efforts in the development of facile and efficient methods for the fabrication of three- and two-dimensional inorganic-organic hybrids based on layered oxide perovskites. Microwave radiation was exploited to rapidly fabricate and modify new and known materials. Despite the extensive utilization of microwaves …

Regioselective Baeyer–Villiger Oxidation Of Lignin Model Compounds With Tin Beta Zeolite Catalyst And Hydrogen Peroxide, John Adam Jennings, Sean R. Parkin, Eric Munson, Sean Delaney, Julie L. Calahan, Mark Isaacs, Kunlun Hong, Mark Crocker

Chemistry Faculty Publications

Lignin depolymerization represents a promising approach to the sustainable production of aromatic molecules. One potential approach to the stepwise depolymerization of lignin involves oxidation of the benzylic alcohol group in β-O-4 and β-1 linkages, followed by Baeyer–Villiger oxidation (BVO) of the resulting ketones and subsequent ester hydrolysis. Towards this goal, BVO reactions were performed on 2-adamantanone, a series of acetophenone derivatives, and lignin model compounds using a tin beta zeolite/hydrogen peroxide biphasic system. XRD, ¹¹⁹Sn MAS NMR spectroscopy, DRUVS and XPS were used to determine tin speciation in the catalyst, the presence of both framework Sn and extra framework …

Graphene Nanoribbons And Their Polymeric Nanocomposites: Controlled Synthesis, Characterization And Applications, Nada M. Aljehany

Electronic Theses & Dissertations

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, Austin W. Bailey

Electronic Theses & Dissertations

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 …

One-Pot Syntheses And Characterizations Of “Click-Able” Polyester Polymers For Potential Biomedical Applications, James F. Beach Ii

Electronic Theses & Dissertations

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 …

Sulfurization Of Nanostructured Cobalt Oxide For Energy Storage Applications, Samiyah Fahad Aloqayli

Electronic Theses & Dissertations

Development of energy storage devices with high energy performance, power density, fast charge-discharge capability and long cyclability is needed to meet the increasing demand for energy, power and environmental protection in our daily life. Supercapacitors have great potential in future energy storage devices with magnificent properties. Recently, researchers have shown great progress for the improvement of supercapacitor performance by fabrication of nanostructured transition metal chalcogenides materials. One of the main objectives of this thesis is to synthesize nanostructured cobalt oxide and then converte them to cobalt sulfide using a facile hydrothermal method. The synthesized cobalt oxide and cobalt sulfide were …

Biowaste Derived Rigid Polyurethane Foams And Supercapacitors: A Renewable And Sustainable Alternative For Petrochemicals, Charith K. R. Akurana Gamaralalage

Electronic Theses & Dissertations

Bio-based polyol for rigid polyurethane (PU) foams and porous structured carbon as an electrode material for supercapacitors were synthesized from readily available biowaste precursor (orange peel) as an alternative to currently used petroleum-based starting materials. Synthesized bio-based polyols were characterized using FTIR, GPC, hydroxyl number, and viscosity measurements. These analyses indicated that intended bio-based polyol was obtained via thiol-ene chemistry with a high yield. Rigid PU foams prepared from bio-based polyol exhibited density around 35 kg/m³, maintained a regular cell structure with uniform cell distribution, closed cell content over 90%, and excellent compressive strength of ~230 kPa, suggesting …

Molecularly Targeted Nanomedicine: Role Of Hsp90 Inhibitor And Sophorolipids In The Treatment Of Lung Cancer, Shuguftha Naz Ms

Electronic Theses & Dissertations

Lactonic sophorolipids (LSL) are a class of enzymatically modified glycolipids known to have HDAC inhibition activity and anticancer properties. Ganetespib (GT), an Hsp90 inhibitor, is known for its superior antitumor activity in several K-RAS mutant Non-Small-Cell Lung Cancer (NSCLC) cells. In this study, a new anti-oxidant nanoplatform is formulated using the combination of these two drugs, LSL and GT, in order to target both HDAC inhibition and Hsp90 signaling pathways in NSCLC. Nanoceria (NC) is an excellent redox platform will be specifically used to supplement the therapeutic potency of these drugs in the effective treatment of NSCLC. We hypothesized that …

Synthesis And Characterization Of Molybdenum Sulfide And For Hydrogen Evolution Reaction And Supercapacitor Applications, Zhuo Wang

Electronic Theses & Dissertations

To meet the constantly rising requirement of energy other than traditional fossil fuel and environment protection, it is a perfect time to development low cost, and efficient materials for clean energy production. Hydrogen generation by water splitting is one of the cleanest ways to produce cheaper energy. Hydrogen evolution reaction (HER) is one of the key steps in water splitting process. Ideally, the thermodynamic potential for HER should be at 0 V (vs. SHE). However, without an efficient catalyst, this reaction occurred at higher potential, called overpotential. A good HER catalyst is needed to lower the overpotential and hence to …

Effects Of Processing Parameters On Properties Of Novel Silica-Filled Polysiloxane Materials, Kyle W. Schwenker

Electronic Theses & Dissertations

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 negatively …