Many coatings only need to either be durable or fast drying, usually sacrificing long term stability in favor of quick setting, or vice versa. One coating type that cannot afford to sacrifice either performance feature is traffic paint. These paints are made up of a weak polycation, an anionic latex, and a volatile base which evaporates upon application. The high pH in the initial formulation deprotonates the polycation, rendering it charge neutral. However, upon evaporation, the resulting drop in pH allows for the electrostatic complexation between the polycation and the latex. The electrostatic interactions used in these formulations parallels that of complex coacervation, an associative liquid-liquid phase separation. In this thesis, we will take advantage of model coacervate systems to elucidate the design parameters necessary for the formulations to serve as paints. We used a series of simplified systems, starting with a system consisting of a weakly cationic homopolymer and weakly anionic homopolymer before moving on to anionic copolymers with decreasing charge density, and ultimately an anionic latex. We investigated the effects of pH, charge stoichiometry, and salt concentration for each of these systems, using turbidimetry and optical microscopy as a means of measuring the extent of coacervation. We determined that, the removal of 99.9% of the charge on our polymers was necessary for coacervation to no longer occur. This can be achieved using either salt or pH, however, salt may be preferable, due to the inherent hazardous properties of highly acidic or basic solutions. Very excitingly, we were able to observe coacervation with latex particles. To our knowledge, there are no known observations of polymer-particle coacervation prior to this study. These results suggest that the underlying physics and design principles associated with fast setting paints can be explored using complex coacervation, and that a much broader range of parameters can be used to control the setting of these materials, beyond just pH used in existing technology. Future efforts are still needed to better understand the effect that polymer chemistry has on the complexation of these materials, and how it also affects the mechanical and adhesive properties of coating produced by such formulations.

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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.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22822号 / 理博第4632号 / 新制||理||1666(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 山本 潤, 教授 佐々 真一, 准教授 荒木 武昭 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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.

The main topic of the thesis was to examine the hydrophobicity of labeling adhesives in the state before drying, it means their resistance against condensated moisture. The problem was solved by measuremensts of contact angle between the drop of water and glue. Measurements of dynamic viscosity and wet tack were also performed for the sake of complex characterization of the glue properties. Comparison of properties among single-component adhesives based on the acrylic copolymers alkalised with various agents was made. The impact of starches and industrial additives on glues was determined by the analysis of primary physical and chemical parameters. The purpose of the measurements was to develop a formula of the glue with enhanced atmospheric moisture resistance, that also would have the required parameters in the equilibrium. Finally, some selected glue samples were practically tested for condensation water resistance. These tests were performed in a climatic chamber with water condensating conditions.

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...

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23226号 / 工博第4870号 / 新制||工||1760(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 田中 一生 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Research areas within the automotive industry are dedicated to reducing the weight and emissions of vehicles. Through the application of lightweight materials, such as polymers, fuel consumption and production costs can be decreased. Therefore, understanding the mechanical responses and failure mechanisms of these materials is significant to the development and design of vehicular structural components. Experimental tests were performed to capture the time, temperature, and stress state dependence, as well as failure mechanisms and large-strain mechanical responses of polypropylene (PP) and copolymer polypropylene (co-PP). Alongside studying the mechanical responses of PP and co-PP, the deformation mechanisms associated with the ductile and brittle failures were also examined. By applying an Internal State Variable (ISV) model, the mechanical behavior of PP and co-PP under various strain rates and temperatures was predicted. Phenomenological, mechanics based failure criteria were also applied to the model to predict the ductile or brittle failure of the materials.

No description available.