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<p> The objective of this work was to investigate the potential of poly(vinyl pyrrolidone) (PVP) as a protein resistant biomaterial. Two types of PVP surface were studied: (1) plasma polymerized N-vinyl pyrrolidone monomer on polyethylene (PE), and (2) grafted PVP surfaces formed by reaction of the activated polymer with plasma polymerized allyl amine on PE. Surfaces were also prepared by grafting polyethylene oxide (PEO), a known protein repellent, to plasma polymerized allyl amine and for comparison to PVP. The surfaces were characterized chemically by water contact angle and X-ray photoelectron spectroscopy (XPS). Protein interactions were studied using radiolabeled fibrinogen in PBS buffer. </p> <p> Plasma polymerized N-vinyl pyrrolidone surfaces were prepared in a microwave plasma reactor. Reactions were carried out both at room temperature and at 50°C (increased vapour pressure) in an attempt to increase the extent of plasma polymer deposition. The resulting surfaces showed structures chemically different from conventional linear PVP. XPS analysis suggested the presence of a variety of functional groups, including amines, amides, hydroxyls, carbonyls and urethanes. Mechanisms for the reactions occurring could not be ascertained but it appeared that the monomer was extensively fragmented in the plasma. Although these surfaces were hydrophilic (contact angles of 20 to 30°), they did not resist fibrinogen adsorption: in fact they showed adsorption levels approximately 10% greater than unmodified polyethylene. </p> <p> Methods for direct grafting of polyvinyl pyrrolidone and polyethylene oxide to plasma polymerized allyl amine (PPAA) surfaces were designed on the assumption that the PPAA surfaces would be rich in amino groups for reaction with appropriate polymer chain ends. Although there was 8-12% of nitrogen on the surfaces, the C1 s high resolution showed that amide and urethane functionalities are also present in addition to amines. The hydroxyl end groups of preformed PEO and PVP chains were activated by reaction with either 1-[3- (dimethylamino) propyl], 3-ethylcarbodiimide and N-hydroxy succinimide (EDC/NHS), and N-N-disuccinimidyl carbonate (DSC). NMR spectra of the products of these reactions showed that for PEO, the yields were moderate, and for PVP, the yields were low. Surfaces grafted using polymers activated with EDC/NHS were more hydrophilic than surfaces grafted with DSC-activated polymers. XPS data did not provide clear evidence that significant polymer grafting had occurred in any of the systems. It was concluded that changes in the allyl amine plasma polymer in different environments following plasma polymerization may affect the efficiency of grafting subsequently. XPS data suggested that the allyl amine plasma surfaces undergo oxidation over time in air. Also the films may be partly removed from the polyethylene surface when placed in buffer as suggested by XPS and contact angle data. Various parameters were examined in an attempt to improve the allyl amine plasma polymerization process for greater stability of the film. Increasing the treatment time from 1 0 to 30 minutes gave surfaces that showed a slower change in contact angle when stored in air. </p> <p> Despite the lack of strong chemical evidence of extensive polymer grafting, all of the grafted surfaces were found to be significantly protein repellent, with reductions of 10 to 36 % compared to unmodified polyethylene. The PEO surfaces were more repellent than the PVP, although the differences were not significant. Surfaces grafted using polymers activated with EDC/NHS were more protein repellent than those grafted with DSC-activated polymers. Protein adsorption was not affected by PVP molecular weight in the range 2,500 to 10,000. Since there is considerable overlap of the molecular weight distributions (MWD) of these two polymers, it is speculated that the MWDs of the grafted polymers may be more similar than those of the polymers themselves, possibly due to "selection" of similar, presumably optimal molecular weights. </p> <p> Discussion of the possible reasons for the better protein resistance of PEO compared to PVP is given in terms of chain structure in relation to the steric exclusion and water barrier theories of protein repulsion. </p> / Thesis / Master of Applied Science (MASc)

ABSTRACT HYDROGEL FROM TEMPLATE POLYMERIZATION OF METHACRYLIC ACID AND N-VINYLPYRROLIDONE AND POLYETHYLENEOXIDE Yelda, Erdem Department of Polymer Science and Technology Supervisor : Prof. Dr. Teoman Tin&ccedil / er April 2005, 53 pages This theses covers the preparation and the characterization of a rigid hydrogel from N-Vinyl pyrrolidone-methacrylic acid (VP-MAA) monomers and polyethyleneoxide (PEO) polymer. Hydrogels are hydrophillic natured three dimensional networks which can swell in the presence of water. The VP-MAA-PEO hydrogel was obtained by template polymerization which can be defined as a method of polymer synthesis in which specific interactions consists of the preparation of a polymer (daughter polymer) in the presence of a macromolecular compound (template polymer). The hydrogel of VP-MAA-PEO was synthesized by using azobisisobutyronitrile (AIBN) as the initiator, tetrahydrofurane (THF) as the solvent and the temperature of the system was kept constant at 50&ordm / C. Two kinds of VP-MAA-PEO hydrogels were prepared. The only difference between them were their solubilities in water. This difference is due to different crosslinking agent weight percentages of ethylene glycol dimethacrylic (EGDMA) to make the hydrogel water insoluble. The comparison of two hydrogels were carried by swelling behaviors at different pH values and different temperatures. Thermal stability of these two hydrogels were also examined by differential scanning calorimetry (DSC), spectroscopic properties were compared by using FTIR spectrometer and morphological studies were analyzed by using scanning electron microscope (SEM).

Mechanical properties of (woven carbon fiber / vinyl ester matrix) composites can be greatly improved if the interphase between the reinforcing high-strength low-weight fiber and the thermoset resin is made more compliant. In order to improve the adhesion of the vinyl ester matrix to the carbon fiber, a thermoplastic coating such as poly(vinyl pyrrolidone) (PVP) can be used as an intermediate between the matrix and the fiber. The extent of mutual diffusion at the (sizing material / polymer matrix) interphase plays a critical role in determining the mechanical properties of the composite. In this research, the molecular interdiffusion across a poly(vinyl pyrrolidone))/vinyl ester monomer (PVP/VE) interface is being investigated by Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) spectroscopy. The ATR method which can be used to characterize the transport phenomena, offers several advantages, such as the ability to monitor the diffusion <I>in situ</I> or to observe chemical reactions. In order to separate the effects of the vinyl ester monomer diffusion and the crosslinking reaction, ATR experiments were carried out at temperatures below the normal curing temperature. Diffusion coefficients were determined by following variations in infrared bands as a function of time, and fitting this data to a Fickian model. The values of the diffusion coefficients calculated were consistent with values found in the literature for diffusion of small molecules in polymers. The dependence of diffusion coefficients on temperature followed the Arrhenius equation. Hydrogen bonding interactions were also characterized. The diffusion model used in this study, however, does not seem to be appropriate for the particular (PVP/VE) system. Because the glass transition temperature of the PVP changed as diffusion proceeded, one would expect that the mutual diffusion coefficient did not stay constant. In fact, it was shown that the Tg can drop by 140oC during the diffusion process. A more suitable model of the (PVP/VE) system should take into account plasticization, hydrogen bonding, and especially a concentration dependent diffusion coefficient. Further analysis is therefore needed. / Master of Science

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19197号 / 農博第2136号 / 新制||農||1034(附属図書館) / 学位論文||H27||N4943(農学部図書室) / 32189 / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 西尾 嘉之, 教授 木村 恒久, 教授 髙野 俊幸 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Additive manufacturing (AM) creates 3D objects out of polymers, ceramics, and metals to enable cost-efficient and rapid production of products from aerospace to biomedical applications. Personalized products manufactured using AM, such as personalized dosage pharmaceuticals, tissue scaffolds, and medical devices, require specific material properties such as biocompatibility and biodegradability, etc. Polymers possess many of these qualities and tuning molecular structure enables a functional material to successfully deliver the intended application. For example, water-soluble polymers such as poly(vinyl pyrrolidone) and poly(ethylene glycol) both function as drug delivery materials because of their inherit water-solubility and biocompatibility. Other polymers such as polylactide and polyglycolide possess hydrolytically cleavable functionalities, which enables degradation in the body. Non-covalent bonds, such as hydrogen bonding and electrostatic interactions, enable strong connections capable of holding materials together, but disconnect with heat or solvation. Taking into consideration some of these polymer functionalities, this dissertation investigates how to utilize them to create functional biomedical products using AM. The investigation of structure-property-processing relationships of polymer molecular structures, physical properties, and processing behaviors is transforming the field of new materials for AM. Even though novel, functional materials for AM continue to be developed, requirements that render a polymeric material printable remain unknown or vague for most AM processes. Materials and printers are usually developed separately, which creates a disconnect between the material printing requirements and fundamental physical properties that enable successful printing. Through the interface of chemistry, biology, chemical engineering, and mechanical engineering, this dissertation aims to relate printability of polymeric materials with three types of AM processes, namely vat photopolymerization, binder jetting, and powder bed fusion. Binder jetting, vat photopolymerization, and powder bed fusion require different viscosity and powder requirements depending on the printer capabilities, and if the material is neat or in solution. Developing scaling relationships between solution viscosity and concentration determined critical overlap (C*) and entanglement (Ce) concentrations, which are related to the printability of the materials. For example, this dissertation discusses and investigates the maximum printable concentration in binder jetting of multiple polymer architectures in solution as a function of C* values of the polymer. For thermal-type printheads, C* appeared to be the highest jettable concentration, which asserted an additional method of material screening for binder jetting. Another investigation of the photokinetics as a function of concentration of photo-active polymers in solution revealed increased viscosity leads to decreased acrylate/acrylamide conversion. Lastly, investigating particle size and shape of poly(stearyl acrylate) particles synthesized through suspension polymerization revealed a combination of crosslinked and linear polymers produced high resolution parts for phase change materials. These analytical screening methods will help the progression of AM and provide future scientists and engineers a better guideline for material screenings. / Doctor of Philosophy / Additive manufacturing (AM), also known as 3D printing, enables the creation of 3D objects in a rapid and cost-efficient manner for applications from aerospace to biomedical sectors. AM particularly benefits the field of personalized biomedical products, such as personalized dosage pharmaceuticals, hearing aids, and prosthetic limbs. In the future, advanced detection and prevention medical screenings will provide doctors, pharmacists, and engineers very precise data to enable personalized healthcare. For example, a patient can take three different medications in one pill with the exact dosage to prevent side-effects and drug-drug interactions. AM enables the delivery and manufacturing of these personalized systems and will improve healthcare in every sector. Investigations of the most effective materials is needed for personalized medicine to become a reality. Polymers, or macromolecules, provide a highly tunable material to become printable with slight chemical modifications. Investigation of how chemical structure affects properties, such as strength, stretchability, or viscosity, will dictate how they perform in a manufacturing setting. This process of investigation is called "structure-property-processing" relationships, which connects scientists and engineers through all disciplines. This method is used to discover which polymers will not only 3D print, but also carry medication to a patient or deliver therapeutics within the body.

Membrane technology has been used in water purification for decades. However, membrane fouling remains a limiting factor. One way to control fouling is through surface modification. Several studies report that increasing surface hydrophilicity can reduce membrane fouling. Surface modification via physical coating (i.e., thin-film composite membrane) was explored in this research to prevent membrane fouling. Before making thin-film composite membranes, it was important to study structure/property relations in a series of potential coating materials. This research aims to contribute to a better fundamental understanding of the structure/property relations which govern water transport, rejection of model foulants (i.e., emulsified oil droplet or protein), and fouling characteristics in hydrogels based on poly(ethylene glycol) diacrylate (PEGDA) and N-vinyl-2-pyrrolidone (NVP). Crosslinked poly(ethylene glycol) (PEG) free-standing films were prepared by UV-induced photopolymerization of PEGDA crosslinker in the presence of varying amounts of water or monofunctional poly(ethylene glycol) acrylate (PEGA). The crosslinked PEGDA films exhibited polymerization induced phase separation (PIPS) when the water content of the prepolymerization mixture was greater than 60 wt%. Visible light absorbance measurements, water uptake, water permeability, and salt kinetic desorption experiments were used to characterize the structure of these phase-separated, crosslinked hydrogels. The films with PIPS exhibited a porous morphology in cryogenic scanning electron microscope (CryoSEM) studies. Dead-end filtration experiments using deionized water and bovine serum albumin (BSA) solutions were performed to explore the fundamental transport and fouling properties of these materials. The total flux of pure water through the films after prior exposure to BSA solution was nearly equal to that of the as-prepared material, indicating that these PEGDA films resist fouling by BSA under the conditions studied. Crosslinked NVP free-standing films were prepared by UV-induced photopolymerization in the presence of water, with NVP as the monomer and N,N’-methylenebisacrylamide (MBAA) as the crosslinker. A series of crosslinked films were polymerized at various prepolymerization water contents, NVP/MBAA ratios and at various levels of UV light intensity in the polymerization. Like PEGDA, the NVP films also underwent phase-separation during polymerization. The influence of monomer/ crosslinker ratio, prepolymerization water content, and UV intensities on membrane morphology and water transport was characterized with CryoSEM, bio-atomic force microscope (Bio-AFM) and dead-end filtration. Molecular weight cutoff (MWCO) measurements were used to characterize the sieving property of crosslinked NVP films polymerized at different UV intensities. UV intensity was found to have an impact on the interconnectivity of crosslinked membranes. Finally, tests of fouling resistance to protein solution (bovine serum albumin) and oily water emulsion were performed. The NVP crosslinked films had good protein and oily water fouling resistance. Overall, both crosslinked PEGDA and NVP films exhibit fouling resistance to oily water emulsions or protein solution. NVP films had more porous structure and higher water permeability than did PEGDA films, while the more compact structure of PEGDA films led to better rejection of model foulants (e.g., protein) than in NVP films. Based on different applications (e.g., oil/water separation, protein filtration), different coating materials must be chosen according to the membrane morphology, transport property, and rejection of model foulants to achieve the highest water flux and foulant rejection in membranes used for water purification. / text

Over the years, secondary metabolites have proven to be significant in the discovery of novel antibiotics and/or lead compounds. Various secondary metabolites have been reported to be produced by fungus of the genus, Alternaria. Here we report the isolation of secondary metabolites by the bioassay-guided fractionation of the ethyl acetate extract of fermentation cultures of the fungus, Alternaria tenuissima. This fungal strain was isolated from the soil underlying the lichen, Peltigera didactyla; and the lichen was collected from Wapusk National Park, a location in Northern Manitoba. The compounds isolated from the fungus include deoxyphomalone, dimethyl 4-methyl-2,6-pyridinedicarboxylate, stemphyperylenol and N-Methyl pyrrolidinone. Their structures were determined by comprehensive analysis of their spectroscopic data including FT-IR, mass spectrometry, 1D and 2D NMR; and their bioactivities were tested against E. coli cells. Some of the compounds demonstrated some bioactivity. The taxonomic identity of the fungus was confirmed by ITS sequencing of its ribosomal DNA.

Master of Science

Hidrogéis são materiais poliméricos com habilidade em intumescer em água e fluidos biológicos sem, contudo, se dissolver. Devido às suas propriedades de maciez e biocompatibilidade, estes materiais têm tido um crescimento enorme na área de engenharia de tecido, encapsulamento de células e liberação de drogas. Este trabalho visa a produção de hidrogéis de poli(N-vinil-2-pirrolidona) e seus copolímeros a partir de reticulações químicas. Como metodologia alternativa de produção de hidrogéis de poli(N-vinil-2-pirrolidona), foi estudada a reticulação do PVP por reação de Fenton, sendo que as concentrações dos reagentes foram avaliadas a fim de produzir um hidrogel com características semelhantes aos hidrogéis de PVP por radiação ionizante. O grande diferencial desta metodologia foi a rápida cinética de gelificação apresentada, creditanto um potencial de aplicação inédito. A partir de reticulações químicas mais brandas, foi estudada a produção de hidrogéis de copolímeros de N-vinil-2-pirrolidona e aldeídos com quitosana, e íons divalentes. Além de estudadas as propriedades relativas ao hidrogel tais como: conteúdo de gel, grau de intumescimento, cinética de reação, citotoxicidade, densidade de reticulação, massa molar média entre as ligações cruzadas e tamanho de poro. / Hydrogels are polymeric materials that have the ability to absorb water and biological fluids in their three-dimensional polymeric matrix without dissolution. Due to their interesting properties, such as softness and biocompatibility, there is a growing interest in their application in tissue engineering, cell encapsulation and drug delivery system. This work aims at the study of hydrogels from poly(N-vinyl-2-pyrrolidone) and copolymers produced by chemical crosslinking methods. PVP crosslinking by Fenton reaction was studied as an alternative methodology to produce poly(N-vinyl-2-pyrrolidone) hydrogels. The reagents concentrations were evaluated, in order to produce a hydrogel with the same properties of the hydrogels prepared by high energy radiation. The advantage of this methodology is its fast jellification kinetic, warranting new potential unprecedented applications. From mild chemical crosslinking methods, the production of hydrogels from copolymers of N-vinyl-2-pyrrolidone and aldehydes with chitosan, and divalent ions was studied. Hydrogels properties as: gel content, swelling ratio, reaction kinetics, cytotoxicity, crosslinking density, molecular weight and pore size were investigated.