Polymer Science Commons^™

The Effect Of Assembly Technique On Weak Polyelectrolyte Multilayer Film Morphology And Humidity Swelling/Deswelling Behavior, Ziyang Yin

Graduate Theses - Chemical Engineering

The goal of this research is to investigate the film morphology and humidity swelling/deswelling behavior of polyelectrolyte multilayers (PEMs) that are constructed from poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) by two assembly techniques: automated dipping layer-by-layer (LbL) and spin-assisted (SA) LbL. Two sets of pH polyelectrolyte solution conditions were tested: (PAH7.5/PAA3.5) and (PAH7.0/PAA7.0). It was found that when the films were constructed with the same number of bilayers (=20 bilayers), SA-LbL (PAH7.5/PAA3.5) has a greater thickness than (PAH7.0/PAA7.0). (PAH7.5/PAA3.5) thin films constructed by automated dipping LbL did not result in a uniform film morphology, making thickness comparisons between techniques …

Development Of Pvdf Membrane Nanocomposites Via Various Functionalization Approaches For Environmental Applications, Douglas M. Davenport, Minghui Gui, Lindell E. Ormsbee, Dibakar Bhattacharyya

Chemical and Materials Engineering Faculty Publications

Membranes are finding wide applications in various fields spanning biological, water, and energy areas. Synthesis of membranes to provide tunable flux, metal sorption, and catalysis has been done through pore functionalization of microfiltration (MF) type membranes with responsive behavior. This methodology provides an opportunity to improve synthetic membrane performance via polymer fabrication and surface modification. By optimizing the polymer coagulation conditions in phase inversion fabrication, spongy polyvinylidene fluoride (PVDF) membranes with high porosity and large internal pore volume were created in lab and full scale. This robust membrane shows a promising mechanical strength as well as high capacity for loading …

Synthesis And Characterization Of Curcumin Polymer For Application In Radiation Induced Lung Damage, Mark C. Bailey

Theses and Dissertations--Chemical and Materials Engineering

Radiotherapy is used as a primary treatment for many cancers, including lung cancer. Although radiotherapy has proven to be an effective cancer treatment, its use is heavily limited due to the peripheral toxicity to healthy tissue. In this work, the antioxidant, curcumin, was tested as a radioprotectant to reduce radiation damage to healthy cells. Curcumin has been limited in use due to its poor bioavailability. In order to avoid problems associated with free curcumin delivery, curcumin poly(beta-amino ester) (CPBAE) was synthesized.

The first study investigated the in vitro radioprotection effect of curcumin in HUVEC dosed with gamma radiation. Cells treated …

Surface-Initiated Polymerizations For The Rapid Sorting Of Rare Cancer Cells, Jacob L. Lilly

Theses and Dissertations--Chemical and Materials Engineering

Cancer metastasis directly accounts for an estimated 90% of all cancer related deaths and is correlated with the presence of malignant cells in systemic circulation. This observed relationship has prompted efforts to develop a fluid biopsy, with the goal of detecting these rare cells in patient peripheral blood as surrogate markers for metastatic disease as a partial replacement or supplement to tissue biopsies. Numerous platforms have been designed, yet these have generally failed to support a reliable fluid biopsy due to poor performance parameters such as low throughput, low purity of enriched antigen positive cells, and insufficiently low detection thresholds …

Separation Of Water From Ulsd Using Superhydrophobic Ps Nanofiber Mats, Alisa G. Webel

Williams Honors College, Honors Research Projects

Superhydrophobic polystyrene nanofiber membranes have potential to separate micron scale water droplets from organic due to their hydrophobicity and small pore openings. Polystyrene nanofibers were electrospun into flat sheets and cylindrical filter membranes. The fibers were crosslinked to increase strength and reduce solubility in diesel fuel. The filters were tested and the filtration efficiency was compared to their non-crosslinked counterparts. The optimal electrospinning conditions to create superhydrophobic nanofibers were found to be 20 wt. % PS fibers at 1 mL/hr. under a current of 20kV and at a distance of 20 cm away from the ground. It was found that …

Construction Of Polyurethane Fabric Nanocomposites For Use In Resistance Temperature Detectors-Effect Of Polyurethane Concentration, Multi-Walled Carbon Nanotubes, And Oxidant, Jordan M. Shaffer

Williams Honors College, Honors Research Projects

Current resistance temperature detectors (RTDs) are rigid and create pressure points when used in contact with the human body. The current RTDs can also not be used in confined areas like the inside of a prosthetic. The research done for this paper explores the possibility of creating a soft fabric like RTD that can accurately measure temperature. This RTD could be used in medical devices, be placed in prosthetic legs, and be worn for a long period of time creating no discomfort for the user. Polyurethane scaffolds were created through an electrospinning process and multiwalled carbon nanotubes were adhered to …

Smart Fabrics For Colorimetric Detection, Breland Edwards

Undergraduate Research Posters

Due to the prevalence of chemical warfare, soldiers often carry chemical sensing devices, to warn of oncoming nerve agents. However, these devices are cumbersome. A lightweight, wearable chemical sensing fabric that doubles as a protectant against toxins would be beneficial. This fabric can be created by incorporating (1) organophosphate hydrolase, an enzyme capable of degrading organophosphates and releasing an acidic by product, and (2) polyaniline, a color changing polymer that changes from purple to green in the presence of acid, into nylon or polyvinyl alcohol nanofibers. The first step is to produce fabrics containing polyaniline and demonstrate that the fabrics …

Bioactive Poly(Beta-Amino Ester) Biomaterials For Treatment Of Infection And Oxidative Stress, Andrew L. Lakes

Theses and Dissertations--Chemical and Materials Engineering

Polymers have deep roots as drug delivery tools, and are widely used in clinical to private settings. Currently, however, numerous traditional therapies exist which may be improved through use of polymeric biomaterials. Through our work with infectious and oxidative stress disease prevention and treatment, we aimed to develop application driven, enhanced therapies utilizing new classes of polymers synthesized in-house. Applying biodegradable poly(β-amino ester) (PBAE) polymers, covalent-addition of bioactive substrates to these PBAEs avoided certain pitfalls of free-loaded and non-degradable drug delivery systems. Further, through variation of polymer ingredients and conditions, we were able to tune degradation rates, release profiles, cellular …

Synthesis And Characterization Of Antioxidant Conjugated Poly(Βeta-Amino Ester) Micro/Nanogels For The Suppression Of Oxidative Stress, Prachi Gupta

Theses and Dissertations--Chemical and Materials Engineering

Oxidative stress is a pathophysiological condition defined by an increased production of reactive oxygen species (ROS), which can result in the growth arrest of cells followed by cell disintegration or necrosis. A number of small molecule antioxidants (e.g. curcumin, quercetin and resveratrol) are capable of directly scavenging ROS, thereby short-circuiting the self-propagating oxidative stress state. However, poor solubility and rapid 1^st pass metabolism results in overall low bioavailability and acts as a barrier for its use as a drug to suppress oxidative stress efficiently.

To overcome this limitation, these small molecule antioxidants were covalently conjugated into poly(β-amino ester) (PβAE) …

Design And Development Of A High-Temperature High-Pressure Rolling Ball Viscometer/Densimeter And Evaluation Of Star Polymer-Solvent Mixtures, Matthew Stanton Newkirk

Theses and Dissertations

Modern automotive applications such as transmission clutch plates, combustion chambers, diesel fuel injector tips, and axle gears and friction plates operate at temperatures that can exceed 250°C and pressures of 40,000 psia. Industrial practice is to add homopolymers and copolymers to base oils to modify bulk fluid viscosity and frictional properties for these demanding applications. However, designing polymeric additives for lubricants and predicting their performance is limited by the lack of available high-temperature high-pressure (HTHP) viscosity and density data needed to test contemporary lubricity models. Thus, a major objective of this thesis is the design, development, and commissioning of a …

Hybrid Aryl-Ether-Ketone And Hyperbranched Epoxy Networks, John Misasi

Dissertations

In this dissertation, relationships between chemical structures, cure kinetics and network architectures are correlated to bulk mechanical properties for novel, hybrid epoxy-amine networks. The work is split into two primary sections: the first is the synthesis and characterization of multifunctional glassy networks based on aryl-ether-ketone diamine curatives, while the second is based on the synthesis and characterization of hyperbranched epoxy polymers and their resulting networks.

Three aryl-ether-ketone (AEK) diamines of increasing molecular weights were synthesized and used to cure 4,4’-tetraglycidylether of diaminodiphenylmethane (TGDDM); the resulting networks were compared to 4,4’-diaminodiphenyl sulfone cured TGDDM. Architectural differences were created by varying cure …

High Temperature Proton Exchange Membranes With Enhanced Proton Conductivities At Low Humidity And High Temperature Based On Polymer Blends And Block Copolymers Of Poly(1,3-Cyclohexadiene) And Poly(Ethylene Glycol), Shawn Deng, Mohammad K. Hassan, Amol Nalawade, Kelly A. Perry, Karren L. More, Kenneth A. Mauritz, Marshall T. Mcdonnell, David J. Keffer, Jimmy W. Mays

Faculty Publications

Hot (at 120 °C) and dry (20% relative humidity) operating conditions benefit fuel cell designs based on proton exchange membranes (PEMs) and hydrogen due to simplified system design and increasing tolerance to fuel impurities. Presented are preparation, partial characterization, and multi-scale modeling of such PEMs based on cross-linked, sulfonated poly(1,3-cyclohexadiene) (xsPCHD) blends and block copolymers with poly(ethylene glycol) (PEG). These low cost materials have proton conductivities 18 times that of current industry standard Nafion at hot, dry operating conditions. Among the membranes studied, the blend xsPCHD-PEG PEM displayed the highest proton conductivity, which exhibits a morphology with higher connectivity of …

Elevated Test Pressure Significantly Reduces Dynamic Accumulation Oxygen Transmission Rate (Astm F3136) Measurement Time For Barrier Packaging Films, Bruce A. Welt

Journal of Applied Packaging Research

Measurement of gas transmission rates of materials is important for successful package design. The dynamic accumulation (DA) method (ASTM F3136) is becoming increasingly popular for measuring oxygen transmission rate (OTR) due to its simplicity and low cost. However, measurement time increases with barrier properties of materials, limiting measurement throughput. A dynamic accumulation measurement prototype capable of operating up to 1,000 psig was developed in order to accelerate gas transfer by boosting concentration gradients via elevated absolute pressures. Results show that measurement results were independent of test pressure while measurement times were substantially reduced. These results also suggest that gas transmission …

Synthesis, Characterization, And Thermoelectric Properties Of Radical Siloxanes, Arnold J. Eng, Bryan Boudouris, Edward P. Tomlinson, Martha Emily Hay

The Summer Undergraduate Research Fellowship (SURF) Symposium

More than half of the annual energy consumption in the United States is lost as waste heat. Polymer-based thermoelectric devices have the potential to utilize this waste heat both sustainably and cost-effectively. Although conjugated polymers currently dominate research in organic thermoelectrics, the potential of using polymers with radical pendant groups have yet to be realized. These polymers have been found to be as conductive as pristine (i.e., not doped) poly(3-hexylthiophene) (P3HT), a commonly-used charge-transporting conjugated polymer. This could yield promising avenues for thermoelectric material design as radical polymers are more synthetically tunable and are hypothesized to have a high Seebeck …

Hydrocarbon-Based Fuel Cell Membranes: Sulfonated Crosslinked Poly(1,3-Cyclohexadiene) Membranes For High Temperature Polymer Electrolyte Fuel Cells, Suxiang Deng, Mohammad K. Hassan, Kenneth A. Mauritz, Jimmy W. Mays

Faculty Publications

High temperature fuel cell membranes based on poly(1,3-cyclohexadiene) were prepared by a Polymerization-Crosslinking-Sulfonation (PCS) approach, and a broad range of membrane compositions were achieved using various sulfonating reagents and reaction conditions. Membranes were characterized for their proton conductivity and thermal degradation behavior. Some of the membranes showed up to a 68% increase in proton conductivity as compared to Nafion under the same conditions (100% relative humidity and 120 °C). Thermogravimetric analysis revealed that these membranes are thermally stable up to 200 °C. High proton conductivity and thermal stability, combined with much lower cost as compared to Nafion®, make these materials …

Morphology And Magnetic Properties Of Sulfonated Poly[Styrene-(Ethylene/Butylene)-Styrene]/Iron Oxide Composites, Sateesh K. Peddini, Huy N. Pham, Leonard Spinu, James L. Weston, David E. Nikles, Kenneth A. Mauritz

Faculty Publications

α-Fe₂O₃ structures were initiated in the sulfonated polystyrene block domains of poly[styrene–(ethylene/butylene)–styrene] (SEBS) block copolymers via a domain-targeted in-situ chemical precipitation method. The crystal structure of these particles was determined using wide-angle X-ray diffraction and selected area electron diffraction using a transmission electron microscope (TEM). TEM revealed that for less sulfonated SEBS (10 mole%), nanoparticles were aggregated with aggregate size range of 100–150 nm whereas for high sulfonation (16 and 20 mole% sSEBS) there were needle-like structures with length and width of 200–250 nm and 50 nm, respectively. Dynamic mechanical analyses suggest that initial iron oxide nanoparticle …

Minimizing Sheet Resistance Of Organic Photovoltaic Cell Top Contact Electrode Layer: Silver Nanowire Concentration Vs. Conductive Polymer Doping Concentration, Caitlyn Cook

Materials Engineering

The top contact electrode layers of nine organic photovoltaic cells were prepared with two varying factors: three Silver nanowire (AgNW) densities deposited on a conductive polymer doped with three concentrations. Silver’s low sheet resistance of 20-Ω/sq is hypothesized to lower the sheet resistance of the anode layer and thus enhance the overall efficiency of the cell. Four-point probe measurements indicated that increasing AgNW density in the top contact electrode layer of an organic photovoltaic cell significantly reduces sheet resistance from 52.2k-Ω/sq to 18.0 Ω/sq. Although an increase in doping concentration of the conductive polymer reduced sheet resistance in low AgNW …

Measuring Performance Of Paint Coating Via Laboratory And Field Testing, Eugene Leung, Rocco Lattanzio

Materials Engineering

No abstract provided.

Bio-Inspired Structural Colors Produced Via Self-Assembly Of Synthetic Melanin Nanoparticles, Ming Xiao, Yiwen Li, Michael C. Allen, Dimitri D. Deheyn, Xiujun Yue, Jiuzhou Zhao, Nathan C. Gianneschi, Matthew D. Shawkey, Ali Dhinojwala

Polymer Science Faculty Research

Structural colors arising from interactions of light with submicron scale periodic structures have been found in many species across all taxa, serving multiple biological functions including sexual signaling, camouflage, and aposematism. Directly inspired by the extensive use of self-assembled melanosomes to produce colors in avian feathers, we set out to synthesize and assemble polydopamine-based synthetic melanin nanoparticles in an effort to fabricate colored films. We have quantitatively demonstrated that synthetic melanin nanoparticles have a high refractive index and broad absorption spanning across the UV–visible range, similar to natural melanins. Utilizing a thin-film interference model, we demonstrated the coloration mechanism of …

Investigating Polymer Based Scaffolds For Urinary Bladder Tissue Engineering, Srikanth Sivaraman

All Dissertations

Current surgical treatments for urinary bladder disorders rely on the use of autologous intestinal segments and xenografts such as small intestinal submucosa, which suffer from various complications including mechanical mismatch and graft shrinkage. Despite early promises of bladder tissue engineering, a recent report of unsuccessful clinical trials suggests that the technology needs further improvement and evaluation through animal models of bladder dysfunction. Therefore, the objective of this doctoral dissertation was to characterize a viable bladder tissue scaffold (patch) which mimics the mechanical properties of the bladder, maintains the phenotype of the BSMC seeded in it and finally, tested in vivo …