京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20404号 / 工博第4341号 / 新制||工||1673(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 澤本 光男, 教授 中條 善樹, 教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21273号 / 工博第4501号 / 新制||工||1700(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 辻井 敬亘, 教授 山子 茂, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21797号 / 工博第4614号 / 新制||工||1719(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 杉野目 道紀, 教授 松田 建児, 教授 大内 誠 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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The addition of isocyanates to C=N double bonds of imines gives triazindione heterocycle structures; their thermal properties are reported. Mono-isocyanates were used to form 2:1 adducts with the imine bases 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 2-tert-butyl-1,1,3,3-tetramethylguanidine (tBuTMG). A 2:1 stoichiometry of the adducts was proven by NMR and IR spectroscopy, and single crystal X-Ray diffraction; certain cleavage temperatures (70 and 160 °C) were measured. Thermal analysis (TG-MS) of adducts indicates the release of free isocyanate during adduct cleavage. Furthermore, a new class of step-growth oligomers (MN = 750–7,000 g∙mol–1) composed of multi-functional isocyanates and these imine bases was introduced. Their systematic spectroscopic and thermal analysis is shown revealing the similarity in their chemical properties to the 2:1 adducts. Radical homo- and copolymerization of acrylates is initiated by the meta-stable adducts and oligomers of this work; the generation of novel telomeric block-copolymer architectures composed of polyacrylate and oligourea building blocks is demonstrated. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24636号 / 工博第5142号 / 新制||工||1982(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 大内 誠, 教授 秋吉 一成, 教授 大北 英生 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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<p>This work focused on grafting water-soluble polymers with well-controlled properties such as tuneable polymer chain length and high graft density to improve the biocompatibility of polymer surfaces via surface-initiated atom transfer radical polymerization (s-ATRP); and on gaining improved fundamental understanding of the mechanisms and factors (e.g., graft chain length and surface density of monomer units) in protein resistance of the water-soluble grafts.</p><p>Protein-resistant polyurethane (PU) surfaces were prepared by grafting watersoluble polymers including poly(oligo(ethylene glycol) methacrylate) (poly(OEGMA)) and poly(l-methacryloyloxyethyl phosphorylcholine) (poly(MPC)) via s-ATRP. A typical three-step procedure was used in the ATRP grafting. First, the substrate surface was treated in an oxygen plasma and reactive sites (-OH and -OOH) were formed upon exposure to air. Second, the substrate surface was immersed in 2-bromoisobutyryl bromide (BffiB)-toluene solution to form a layer of ATRP initiator. Finally, target polymer was grafted from the initiator-immobilized surface by s-ATRP with Cu(I)Br/2bpy complex as catalyst. The graft chain length was adjusted by varying the molar ratio of monomer to sacrificial initiator in solution. The modified PU surfaces were characterized by water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM).</p><p>Protein adsorption experiments were carried out to evaluate the protein resistance of the surfaces. Adsorption from single and binary protein solutions as well as from plasma decreased significantly after poly(OEGMA) grafting, and decreased with increasing poly(OEGMA) main chain length. Fibrinogen (Fg) adsorption on the most resistant surfaces (chain length 200 units) was in the range of 3-33 ng/cm^2, representing a reduction of more than 96% compared to the control surfaces.</p><p>OEGMA monomers with three different molecular weights (MW 300, 475, 1100 g/mol) were used to achieve different side chain lengths of poly(OEGMA). Fibrinogen (Fg) and lysozyme (Lys) were used as model proteins in adsorption experiments. The effects of side chain length as well as main chain length were then investigated. It was found that adsorption to the poly(OEGMA)-grafted PU (PU/PO) surfaces was protein size dependent. Resistance was greater for the larger protein. For grafts of a given side chain length, the adsorption of both proteins decreased with increasing polymer main chain length. For a given main chain length, the adsorption of Fg, the larger protein, was independent of side chain length. Surprisingly, however, Lys (the smaller protein) adsorption increased with increasing side chain length. A reasonable explanation is that graft main chain density decreased as monomer size and footprint on the surface increased. Protein size-based discrimination suggests that the chain density was lower than required to form layers in the "brush" regime in which protein size is expected to have little effect on protein adsorption.</p><p>In order to achieve high surface densities of ethylene oxide (EO) units, we used a sequential double grafting approach whereby the surface was grafted first with poly(2-hydroxyethyl methacrylate) (HEMA) by s-ATRP. OEGMA grafts were then grown from the hydroxyl groups on HEMA chains by a second ATRP. The effect of EO density on protein-resistant properties was then investigated. Protein adsorption on the sequentiallygrafted poly(HEMA)-poly(OEGMA) surfaces (PU/PH/PO) was not only significantly lower than on the unmodified PU as expected, but also much lower than on the PU/PO surfaces with the same poly(OEGMA) chain length. Moreover, protein adsorption decreased with increasing EO density for these grafts. On the PU/PH/PO surface with a poly(OEGMA) chain length of 100, the adsorption of Ls and Fg were reduced by ~98% and >99%, respectively, compared to the unmodified PU. Binary protein adsorption experiments showed that suppression of protein adsorption on the PU/PH/PO surfaces was essentially independent of protein size. The double-grafted OEG layers resisted both proteins equally.</p><p>The general applicability of this approach which combines oxygen plasma treatment and ATRP grafting was also studied. Various kinds of polymers such as PU, silicone hydrogel, and polydimethylsiloxane (PDMS) were chosen as substrates. Poly(MPC) grafts with different chain lengths were achieved by the three-step ATRPgrafting procedure. It was found that protein adsorption levels on the poly(MPC) grafts were significantly lower than on the respective unmodified surfaces. Protein adsorption decreased with increasing poly(MPC) chain length. Among the surfaces investigated, PU/MPC showed the highest protein resistance for a given chain length.</p> / Thesis / Doctor of Philosophy (PhD)

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