High molecular weight poly(phenylene sulfide sulfone) (PPSS) homo- and statistical copolymers have been reproducably synthesized using a known, but complex procedure utilizing 4,4'-dichlorodiphenyl sulfone (DCDPS), sodium hydrosulfide, sodium hydroxide, sodium acetate, and deionized water, in NMP at elevated reaction temperatures and pressure. The effect of these variations, e.g., reaction temperatures and times, molar ratios of H2O-to-NaSH, NMP-to-H2O, etc. were investigated. Optimized conditions were defined, which produced Tg as high as 222°C, very high refractive index (1.70), and tough/solvent resistant films could be prepared by melt fabrication. A two-stage decomposition mechanism in air was demonstrated by dynamic thermal gravimetric analysis. The melt stability of PPSS was improved by incorporating thermally stable endgroups, such as diphenyl sulfone, 4-chlorophenylphenyl sulfone, and t-butylphenoxide. The chemical structures of the endgroups were confirmed by 13C and 1H NMR spectra. Compared with mercaptide endcapped PPSS, the new systems showed higher initial degradation temperatures (2% and 5% weight loss), higher char yield at 650°C in air and a more stable melt viscosity at 300°C. A greatly simplified synthesis of both homo and copolymers has been successfully developed using the new A-A or A-B type thiol-functional monomers, such as bis-(4-mercaptophenyl) sulfone, 4-chloro-4'-mercaptodiphenyl sulfone and 4-chloro-4'-mercapto benzophenone, instead of sodium hydrosulfide. A series of high molecular weight triphenyl phosphine oxide and/or diphenyl ketone containing PPSS copolymers were subsequently synthesized from the bis-(4-mercaptophenyl) sulfone by reaction with 4,4'-dichlorodiphenyl sulfone, bis-(4-fluorophenyl) phenyl phosphine oxide, and 4,4'-difluorobenzophenone in DMAc in the presence of K2CO3 at 160°C. The new phosphine oxide containing PPSS copolymers were completely amorphous, showed improved solubility in common organic solvents and exhibited very high char yields in air at 750°C. Surface (XPS) analysis results suggested that the phosphorus moieties in the polymer backbone can form phosphate-like layers on the polymer surface which protects the inner materials from further decomposition in air at high temperatures. The diphenyl ketone containing PPSS copolymers showed very high char yields at 750°C in a nitrogen atmosphere, compared to sulfide sulfone homopolymer and phosphine oxide containing copolymers, possibly because of higher bond energies. Semi-crystalline poly(phenylene sulfide ketone) homopolymers and sulfone containing copolymers with sulfone/ketone mole ratio (S : K) < 25 : 75 were synthesized by a novel base catalyzed self-polycondensation of 4-chloro-4'-mercaptodiphenyl sulfone and/or 4-chloro-4'-mercapto benzophenone in N-cyclohexyl-2-pyrrolidinone (CHP) at 290°C. Amorphous copolymers with S : K ratios > 25 : 75 were prepared in DMAc at 160°C. These materials exhibited an increase in glass transition temperature with increasing sulfone content. TGA and micro cone calorimetry analyses showed that the semi-crystalline materials with high ketone content had much higher char yields and significantly lower heat release rate and total heat release, compared to the poly(phenylene sulfide sulfone) and poly(pheylene sulfide) controls. / Ph. D.

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Over 30% of the world's population does not have access to safe drinking water, and the need for clean water spans further than just for human consumption. Currently, we use freshwater for growing agriculture, raising livestock, generating power, sanitizing waste, mining resources, and fabricating consumer goods. With that being said, the world is beginning to feel pressure from the excessive freshwater withdrawal compared to the current freshwater supply. This water stress is causing a water crisis. Places including Australia, South Africa, and California in the United States, just to name a few, are beginning to run out of fresh water to support daily societal demands. This is a phenomenon that is indiscriminately observed in all ranges of economically and politically developed countries and environments. However, it is important to note that less politically and economically developed countries especially those in arid climates, experience higher water stress than countries without such qualities. With only 2.5% of the world's water being freshwater and 30% of it being accessible as either ground or surface water, freshwater is a scarce resource, especially with the growing population and society's demand for water. Since the remaining 97.5% of water is composed of either brackish or seawater (saline water sources), one way to overcome the water stress would be to convert saline water into freshwater. As a result, various desalination techniques have been developed in the last 80 years that employ either membrane technology or temperature alterations to desalinate either brackish or seawater. One of the fastest growing methods for producing freshwater is reverse osmosis. Reverse osmosis uses an externally applied pressure, in the form of a cross flow back pressure, to overcome the osmotic pressure produced by the saline gradient across a semi-permeable membrane. The semi permeable membrane commercially consists of an interfacially polymerized aromatic polyamide thin film composite with a polysulfone porous backing that allows water to pass through while barring the transport of salt ions. This research focuses on the development of sulfonated poly(arylene ether sulfone) derivatives with differing amounts of sulfonation and with the ions placed at different structural positions. Previously, such materials were tested as potential high performance fuel cell membranes, but they are also of interest as potential high performance water desalination membranes, specifically for reverse osmosis. Two different methods were used to synthesize the sulfonated polysulfone derivatives: direct polymerization and post-modification of a non-sulfonated active polysulfone. The polysulfones from direct polymerization incorporated specialty sulfonated monomers, which were stoichiometrically controlled during the polymerization. Sulfonated polysulfones that were synthesized from post sulfonation incorporated biphenol and hydroquinone monomer units randomly throughout the polysufone backbones. These units could be sulfonated selectively because of their activation towards electrophilic aromatic substitution with sulfuric acid. Each of the polymers were cast into films ranging between 20-100 microns in thickness and tested for water uptake, hydrated uniaxial tensile properties, crossflow water and salt transport properties, and for crosslinked samples, gel fractions. The water uptakes from all the polysulfones were tuned by the degree of sulfonation or disulfonation present in the polymer. This was either controlled via the presence of a sulfonated monomer or a monomer that was active toward electrophilic aromatic substitution after polycondensation of the polysulfone. All polymers exhibited increases in their water uptake as the degree of sulfonation increased. We also observed a decreasing trend in the hydrated mechanical properties of the films for all the high molecular weight linear polymers as the water uptake was increased. The directly polymerized sulfonated polysulfones were found to have high hydrated elastic moduli ranging between 400 and 1000 MPa, while the post sulfonated counterparts (with either hydroquinone or biphenol incorporated in their structures) exhibited elastic moduli ranging between 1000 and 1500 MPa. It is important to note that the structures of the polymers were slightly different from one another because of the technique used to synthesize them. Thus, the increases in hydrated moduli among polymers synthesized via different routes may have influences from differences in chemical structures. Some of the polymers with higher degrees of sulfonation were synthesized as amine terminated oligomers with varying controlled molecular weights. The two targeted molecular weights were 5 and 10 kDa. Those oligomers were then crosslinked with a tetra-functional epoxide agent. The increases in sulfonation allowed for increases in water uptake and in theory, the water throughput through the sulfonated polysulfone membrane. Decreases in hydrated mechanical performance of the crosslinked networks with increasing degrees of sulfonation were also observed, similar to their high molecular weight linear counterparts. The directly polymerized crosslinked networks had salt permeabilities that plateaued at 70% disulfonation for both the 5 and 10 kDa polymers. Thus, we expect disulfonation content greater than 70% would lead to higher water throughput without significant increases in salt transport. / Doctor of Philosophy / A worldwide shortage of freshwater is becoming more problematic by each passing day. The World Health Organization and the United Nation's World Water Assessment Program predict that by 2025, 50-66% of the world's population will be living in a water-stressed area. This includes any area that experiences higher clean water withdrawals than are available. This includes but is not limited to areas that are politically unstable, technologically disadvantaged, resource deficient, located in arid climates, and highly populated. To put this further into perspective, only 2.5% of the available water on earth is freshwater. Freshwater typically has low concentrations of dissolved salts that are safe for human consumption and use. Of the available freshwater, only 30% of it is actually accessible for use through either surface or groundwater reservoirs, making the amount of clean water available for usage already a scarce resource. On the other hand, 97.5% of the world's water is composed of saline water reservoirs in the form of brackish and seawater. Through harnessing, seawater and removing the excess dissolved salt ions, the salt water can be converted to freshwater. Two major methods have been developed to remove the dissolved ions from water through either membrane filtration or thermal phase changes. One of the fastest growing membrane filtration techniques used worldwide is reverse osmosis. Reverse osmosis refers to the use of applied pressure across a semipermeable membrane to desalinate saline water. The semipermeable membrane prevents the migration of salt ions through the membrane while allowing transport of water. This work has focused on developing new polymers that can increase the overall efficiency of water desalination. Different types of high performance sulfonated polysulfone derivative polymers were synthesized and used to make membranes that were subsequently tested for performance. Relationships between the polymer structure, process, and properties were quantified through different analytical techniques. This study showed how the properties of sulfonated polysulfone membranes may be manipulated depending on structural modifications and processing to increase both the material's water throughput and salt rejection.

Every year, millions of people contract antibiotic-resistant bacterial infections, and tens of thousands die from infection-related complications in the United States alone. Bacterial infections are one of the leading causes of death worldwide, especially in healthcare institutes such as hospitals and nursing homes where people are more susceptible to infection and complications. Bacteria can cause infections in any part of the body and often interact with sugar molecules on the surface of cells; once bacteria are attached, the cells stop functioning properly. When a bacterial infection is suspected, samples from the patient's blood or urine are taken to confirm the diagnosis. If the bacterial infection is sever enough, patients are treated with broad-spectrum antibiotics before the type of bacteria is known, and once it has been identified they are given antibiotics that target the specific bacterial strain. The high death rate associated with bacterial infections is largely due to the emergence of antibiotic-resistant bacterial strains. Although antibiotic resistance is present in some naturally occurring bacterial strains, misuse and over-prescription of antibiotics have accelerated the process. To combat the ever-growing threat of antibiotic-resistant bacteria, antibacterial polymers have been developed. Antibacterial polymers prevent bacterial infections by either killing the bacteria themselves or by preventing them from interacting with the body altogether This dissertation primarily focuses on using sugar-containing polymers to prevent bacterial growth. These materials may potentially be used as a replacement for or supplement to traditional antibiotics. / Doctor of Philosophy / All living cells possess a coating of glycomaterials on, or as critical components of their cell walls. Bacteria, including invasive bacterial pathogens, are no exception and have cell walls comprised of peptidoglycans. Glycomaterials on cell surfaces play a role in critical biological processes such as molecular recognition, cellular interaction, infection, and inflammation. Traditional antibiotic remediations are becoming less effective in treating bacterial infections due to the emergence of antibiotic-resistant strains. The formation of biofilms, an extracellular coating composed of polysaccharides, contributes to the antibiotic resistance of bacteria. The development of novel antibiotics is extremely costly and often unsuccessful, with billions in investment often producing zero new drugs. As a result, antibacterial polymers have been investigated as they are comparatively less expensive and offer unique characteristics to combat bacterial infections. Polymers with inherently antibacterial properties, or those that can be conjugated with antibacterial compounds, offer a replacement for traditional antibiotic remediation. To investigate the role of glycomaterials in antibacterial activity, a series of sugar-containing norbornene homopolymers were prepared and evaluated for their antibacterial activity. Protected glycomonomers consisting of galactose, glucose, N-acetyl glucose, and mannose were prepared in a two- or three-step synthesis by first appending an acrylate to the anomeric carbon through Koenigs-Knorr-type chemistry. After generation of the -anomer, the norbornene carboxylate was prepared by the Diels-Alder reaction of the acrylate with cyclopentadiene. Homopolymers with molecular weights ranging from 25–250 KDa were synthesized using ring-opening metathesis polymerization (ROMP) catalyzed by Grubbs 3rd generation catalyst, and subsequently deprotected to reveal the sugar-norbornene. While the galactose polymers showed no bacterial inhibition, those composed of glucose, N-acetyl glucose, or mannose prevented the growth of Escherichia coli (E. coli) and were effective at concentrations as low as 1.25 mg mL-1. Some strains of pathogenic bacteria, such as Clostridioides difficile (formerly known as Clostridium difficile), interfere with the normal cell functions by indirect means, producing toxins that adversely interact with the surrounding tissue. To sequester the toxins produced by C. difficile before they cause damage to the gastrointestinal (GI) tract, polymers containing the -gal epitope, a naturally occurring trisaccharide, were also prepared. The -gal epitope possessing a propyl azide handle at the anomeric carbon was prepared in a 15-step reaction, followed by reaction with an alkyne-functionalized polymer resin using copper-catalyzed azide-alkyne Huisgen cycloaddition. After global deprotection and thorough washing to remove residual copper from the glycomaterial, cell viability studies showed >80% cell survival. While these materials showed good cell viability, the rigorous synthesis of -Gal and the affinity of the polymer scaffolding for copper was a deterrent to further toxin-binding studies. Non-biological surfaces are also often susceptible to bacterial colonization and fouling. Although such materials may be modified to impart antimicrobial properties, their modification may also be a detriment to other key physical properties. To investigate the tradeoffs between material properties and functionalization, we synthesized a series of poly(arylene ether)s from monomers that possessed a modifiable handle and differed only in the pattern of leaving group on the aromatic ring. These polymers were further modified using post-polymerization thiol-ene reactions to evaluate the effect of the side-chains on the material's properties. The regioisomer incorporated into the polymer was found to influence its thermal properties irrespective of the installed functional group, suggesting that new functionality can be incorporated into these polymers without adversely impacting their physical properties.