京都大学 / 新制・課程博士 / 博士(工学) / 甲第23920号 / 工博第5007号 / 新制||工||1781(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 秋吉 一成, 教授 大内 誠, 教授 大塚 浩二 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16883号 / 工博第3604号 / 新制||工||1544(附属図書館) / 29558 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 長谷川 博一, 教授 吉﨑 武尚, 教授 金谷 利治 / 学位規則第4条第1項該当

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Výzkum v této práci byl zaměřen na přípravu a charakterizaci blokových kopolymerů typu polypropylen-blok-poly(propylenu-co-ethylenu) (dále jen PP-blok-EPR). Tyto materiály jsou považovány za účinné kompatibilizátory mezi semi-krystalickou polypropylenovou (PP) matricí a amorfními doménami statistického kopolymeru propylenu a etylenu (EPR) v rázuvzdorném sekvenčním kopolymeru (ICP) a proto byl výzkum zaměřen na zkoumání vlivu přídavku blokového kopolymeru PP-blok-EPR na vlastnosti komerčního ICP. Blokové kopolymery byly připraveny za použití techniky „stopped-flow“. Pro tento účel byla zkonstruována vysokotlaká polymerační „stopped-flow“ aparatura, která umožňuje syntézu kopolymerů PP-blok-EPR za podmínek blízkých podmínkám v průmyslových reaktorech pro výrobu komerčních ICP materiálů. Aparatura umožňuje vyrábět PP-blok-EPR polymer v množství dostačující na jeho charakterizaci a následnou přípravu směsí s komerčním ICP. Velmi krátké polymerační časy (obvykle kolem 0.2 s) kterých bylo dosaženo v kapilárním reaktoru aparatury „stopped-flow“ zajišťuje, že aktivní centra Ziglorova-Nattova katalyzátoru produkují polymer řetězce skládající se z bloku semikrystalického polypropylenu a bloku amorfního EPR kopolymeru. Takovéto molekuly jsou v literatuře popsány jako „skutečné blokové kopolymery PP-blok-EPR“. Kopolymery syntetizované v aparatuře „stopped-flow“ byly frakcionovány preparativní TREF (Temperature Rising Elution Fractionation) metodou a získané frakce byly následně analyzovány pomocí DSC, 13C-NMR a GPC/SEC. Tyto analýzy odhalily přítomnost amorfního EPR ve vysoce krystalické frakci (100-140 °C). Toto zjištění potvrdilo, že významná část polymerních řetězců, připravených v aparatuře „stopped-flow“ jsou blokové kopolymery skládající se z bloku semikrystalického PP homopolymeru a bloku amorfního EPR kopolymeru v jednom polymerním řetězci. Kopolymery získané metodou „stopped-flow" byly v tavenině smíchány s komerčním rázuvdorným kopolymerem ICP. U takto připravených směsí byly vyhodnoceny mechanické vlastnosti, DTMA a reologické vlastnosti a výsledky byly srovnány s vlastmi původního komerčního ICP kopolymeru. Dále byly studovány rozdíly v morfologii a umístění EPR domén v matrici PP prostřednictvím SEM. Zřetelný vliv kopolymeru PP-blok-EPR na vlastnosti ICP byl pozorován zejména v morfologických změnách EPR domén dispergovaných v PP matrici. Tyto změny mají pozitivní vliv na rovnováhu mezi modulem v ohybu a rázovou pevností ICP materiálu. Vliv kopolymeru PP-blok-EPR na reologické vlastnosti ICP byl nevýznamný. Podobně také v případě DTMA nebyl pozorován významný vliv kopolymeru PP-blok-EPR na vlastnosti ICP.

Isoporous membranes manufactured from diblock copolymer are successfully produced at laboratory scale under controlled conditions. Because of the complex phenomena involved, membrane preparation requires trial and error methodologies to find the optimal conditions, leading to a considerable demand of resources. Experimental insights demonstrate that the self-assembly of the block copolymers in solution has an effect on the final membrane structure. Nevertheless, the complete understanding of these multi-scale phenomena is elusive. Herein we use the coarse-grained method Dissipative Particle Dynamics to study the self-assembly of block copolymers that are used for the preparation of the membranes. To simulate representative time and length scales, we introduce a framework for model reduction of polymer chain representations for dissipative particle dynamics, which preserves the properties governing the phase equilibria. We reduce the number of degrees of freedom by accounting for the correlation between beads in fine-grained models via power laws and the consistent scaling of the simulation parameters. The coarse-graining models are consistent with the experimental evidence, showing a morphological transition of the aggregates as the polymer concentration and solvent affinity change. We show that hexagonal packing of the micelles can occur in solution within different windows of polymer concentration depending on the solvent affinity. However, the shape and size dispersion of the micelles determine the characteristic arrangement. We describe the order of crew-cut micelles using a rigid-sphere approximation and propose different phase parameters that characterize the emergence of monodisperse-spherical micelles in solution. Additionally, we investigate the effect of blending asymmetric diblock copolymers (AB/AC) over the properties of the membranes. We observe that the co-assembly mechanism localizes the AC molecules at the interface of A and B domains, and induces the swelling of the B-rich domains. The B-C interactions control the curvature of the assemblies in these blends. Finally, we study the self-assembly triblock copolymers used for membranes fabrication. We show that the polymer concentration, the block-copolymer composition, and the swelling of the micelle are responsible for the formation of elongated micelles in the casting solution. The formation of nanoporous membranes arises from the network-like packing of those micelles.

Title: Self-assembly of polyelectrolytes in aqueous solutions (dissipative particle dynamics) Author: Karel Šindelka Department: Faculty of science, Charles University in Prague Supervisor: Doc. Ing. Zuzana Limpouchová, CSc. Consultant: Doc. Ing. Martin Lísal, DSc. Abstract In the thesis, the coarse-grained dissipative particle dynamics (DPD) is used for the study of self-assembly of equimolar mixtures of oppositely charged symmetric block PEs with one PE block (either strong polycation or strong polyanion) and one readily water-soluble neutral block in aqueous media. In the first part of the diploma thesis, the principles of DPD simulations are described and the correct implementation of electrostatic interactions in the DPD method is demonstrated on the example of counterion (Manning) condensation. In the second main part, the effect of the blocks solubility, incompatibility and the interplay of different forces on electrostatic assembly is investigated. The cor- responding neutral systems are also simulated for comparison. The study shows that the hydrophobicity of the PE backbone and the incompatibility of blocks sig- nificantly affects the electrsotatic co-assembly. The presence of opposite charges on different chains promotes the aggregation process and the aggregation number in- creases in comparison...

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Polylactide (PLA) is a biodegradable and biocompatible polymer which is attracting much attention for environmental issues imposed by the petroleum-based polymers. PLA can be used as medical polymer in surgical sutures, implants tissue and many other areas. However, one of the main shortcomings of PLA is its brittleness in nature and relatively poor mechanical properties, which often limits its further application. It is generally accepted for polymeric materials that some mechanical properties of oriented structures can be improved as the molecular weight of PLA increases. The outcome of this thesis will provide the knowhow to achieve ultrahigh molecular weight of polylactides, and further to improve the mechanical properties and extend its range of applications. In this work, different catalytic systems for the synthesis of ultra-high molecular weight (UHMW) polylactide are considered. For the catalytic systems considered, the reaction conditions and initiators are investigated. The resulting molecular characteristics and mechanical properties of the synthesized polymers will be evaluated. On the contrary to the brittle nature of PLA, Poly(ε-carprolactone) (PCL) is elastic and flexible with a relatively low melting point (60 oC) and low glass transition temperature (-60 oC). Hence, ultra-high molecular weight PCL will be also synthesized by using the same catalytic systems employed for achieving UHMWPLAs. PCL is also used in different biomedical applications, such as in scaffolds for tissue engineering. It is well documented that the complementary physical properties of PLA and PCL have the potential to enhance toughness of PLA. To enhance the toughness and mechanical properties of the block copolymers attempt is made to synthesize ultra-high molar mass of the two polymers in the block copolymer. But their molar masses (and consequently their mechanical properties) are always on the low side. For this reason, the synthesis of high molecular mass PLA and PCL multiblocks will be attempted. Furthermore, it is interesting to study the synthesis of high molar masses PLLA and PDLA stereoblocks especially their ability to crystallize during the polymerization and test the possibility to prepare stereocomplex only during synthesis. The resulting molecular characteristics and mechanical properties of the synthesized multiblock-polymers will be also evaluated.