This research work examines the process of block copolymer membrane fabrication by self-assembly combined by non-solvent induced phase separation. Self-assembly takes place from the preparation of the primordial solution until the moment of immersion in a non-solvent bath. These mechanisms are driven thermodynamically but are limited by kinetic factors. It is shown in this work how the ordering of the assembly of micelles is improved by the solution parameters such as solvent quality and concentration of block copolymer. Order transitions are detected, yielding changes in the morphology. The evaporation of the solvents after casting is demonstrated to be essential to reach optimum membrane structure. The non-solvent bath stops the phase separation at an optimum evaporation time.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17891号 / 工博第3800号 / 新制||工||1581(附属図書館) / 30711 / 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 金谷 利治, 准教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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Self-assembly is an autonomous process where components organize themselves into structures via noncovalent interactions without human intervention. Ultrashort amphiphilic peptides are typical self-assembly molecules with specific sequence motifs which consist of three to seven amino acids. Due to their amphiphilic structure which carries a dominant hydrophobic tail and a polar head group, these peptides can self-assemble to construct nanofibrous scaffolds system to form hydrogels, organogels or aerogels. The nanofibrous scaffolds formed by amphiphilic peptides are very similar to the fiber structure found in collagen which plays an essential role in extracellular matrix showing the potential of applying these peptide scaffolds together in culturing native human cells. Thus the derivate of amphiphilic peptides depsipeptide in which we replaced one amide bond with an ester bond is also worthwhile to explore a novel penitential material for Tissue Engineering. At the same time, because of the perfect biocompatibility of amphiphilic peptides made up of natural l-amino acids and also the excellent gelation properties providing a solution for zinc dendrite growth in Zn batteries, it will be also meaningful to combine the rationally designed peptide gelation system to Zn batteries. This dissertation describes how to characterize and use ultrashort amphiphilic depsipeptide for tissue engineering and use ultrashort amphiphilic peptide for the electrolyte of Zn batteries. The first chapter provides us with an introduction to self-assembly material, 3D bioprinting, and Zn batteries. The second chapter introduces a novel method to synthesize the depsipeptide fully based on solid phase peptide synthesis (SPPS) and also shows the different properties, especially the gelation behavior by clarifying its mechanism via doing the characterization of depsipeptide. At the end of the second chapter, depsipeptide is proved to be a potential material in 3D bioprinting. The third chapter reveals how we synthesized and characterized the amphiphilic peptide and applied it to the Zn batteries. The cycling stability got promoted compared with bard Zn batteries in symmetrical Zn-Zn cells while the formation of Zn dendrite was also suppressed. The promising results suggest peptide gelation systems are promising electrolytes for use in Zn batteries.

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Microfluidics is the science of processing microliters or less of fluid at a time in a channel with dimensions on the order of microns. The small size of the channels allows fluid properties to be studied in a world dominated by viscosity, surface tension, and diffusion rather than gravity and inertia. Microfluidic droplet generation is a well studied and understood phenomena, which has attracted attention due to its potential applications in biology, medicine, chemistry and a wide range of industries. This dissertation adds to the field of microfluidic droplet studies by studying individual droplet deformation and the process of scaling-up microfluidic devices for industrial use. The study of droplet deformation under extensional and mixed shear and extensional flows was performed within a microfluidic device. Droplets were generated using a flow-focusing device and then sent through a hyperbolic contraction downstream of the droplet generator. The hyperbolic contraction allowed the smallest droplets to be deformed by purely extensional flows and for the larger droplets to experience mixed extensional and shear flows. The shear resulted from the proximity of the droplet to the walls of the microfluidic channel. The continuous phase in all of these devices was oil and the dispersed phase was water, an aqueous surfactant solution, or an aqueous suspension of colloidal particles. Droplet deformation dynamics are affected by the use of surfactants and colloidal particles, which are commonly used to stabilize emulsion droplets again coalescence. Microfluidic droplet generating devices have many potential industrial applications, however, due to the low output of product from a single droplet generating device, their potential has not been realized. Using six parallel flow-focusing droplet generators on a single chip, the process of microfluidic droplet formation can be scaled up, thus resulting in a higher output of droplets. The tuning of droplet size and production frequency can be achieved on chip by varying the outlet tubing lengths, thus allowing for a single device to be used to generate a range of droplet sizes.

The equilibrium phase behavior of disperse diblock copolymers is studied using the self-consistent field theory. We first examine how dispersity affects the formation of complex spherical phases in conformationally asymmetric diblock copolymers. For disperse diblock copolymers with Poisson and Schulz-Zimm distributions, the Frank-Kasper σ phase appears at a lower degree of conformational asymmetry than what is predicted in monodisperse systems. We next present a general method of treating molecular weight distributions (MWDs) specified by a set of molecular weight fractions in numerical self-consistent field theory. The procedure is applied to MWDs with similar dispersity indices and different skewness obtained from experimental measurements. We find that consistent with experiments, the domain spacing and equilibrium morphology could vary with the skewness. Lastly, we investigate how the MWD shape characterized by the dispersity index and skewness affects the relative stability of complex spherical phases. The predicted set of complex phases could differ between MWDs with identical dispersity indices and different skewness. In particular, it is found that the formation of the C14 and C15 phases is favored for more positively-skewed distributions. Overall, the work underlines the importance of the MWD shape on the phase behavior of disperse diblock copolymers and the need of considering other statistical measures alongside the dispersity index, such as the skewness. / Dissertation / Doctor of Philosophy (PhD)

Automotive assembly plants work on a pre-planned job sequence in order to optimize the performance of the assembly line. However, the job sequence becomes scrambled due to factors such as plant layout, process design, variability and uncertainty. Assembly plants use either a mix-bank or an automatic storage and retrieval system to regenerate the sequence before final assembly. A mix-bank, which is a set of parallel lanes, is the most common method used in the automotive industry to reconstruct the sequence. Only the first vehicles on the lanes are available for sequencing in a mix-bank set-up. Hence the lane selection policy and the lane configuration of a mix-bank play crucial roles in recreating the sequence. This thesis addresses the problem of identifying a superior lane selection policy for a mix-bank re-sequencing area. Simulation models of a re-sequencing area are used to evaluate lane selection policies. Varying the lane configurations and the nature of sequence tests the effectiveness of the selection policies.

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