The synthesis, characterization and amphiphilic self-assembly of polymer brush functionalized nanoparticles (PBNPs) using a block copolymer template is described herein. To study the effect of polymer brush composition on self-assembly, four samples were created using a mixture of PS-b-PAA (polystyrene-block-polyacrylic acid) and PMMA-b-PAA (poly(methyl methacrylate)-block-polyacrylic acid) diblock copolymers to create PBNPs with a CdS quantum dot (QD) core and different ratios of PS and PMMA in the coronal brush. Static light scattering showed that despite differences in brush composition, the PBNPs formed nanoparticles of similar aggregation number and chain density but showed evidence of asymmetric structure in a common solvent for both blocks at higher PS contents. After subsequent hydrolysis of the hydrophobic PMMA to hydrophilic poly(methacrylic acid) (PMAA), these amphiphilic particles were then self-assembled in THF/H2O solution in which it was determined that increasing the hydrophobic content of the brush composition, the initial nanoparticle concentration (c0) or the added salt content (RNaCl), would cause the assembly of low curvature assemblies. Compilation of this data allowed for the construction of phase diagrams for PBNP systems based on brush composition and c0 at different salt contents. Lastly, PS-b-PAA-b-PMMA triblock copolymers with variable PMMA chain length were assembled into PBNPs around a CdS QD core using a block copolymer template approach. Light scattering showed these particles also had similar aggregation number and chain density despite the difference in PMMA chain length. After hydrolysis of PMMA to PMAA these particles were then self-assembled in THF/H2O mixtures to determine the role of PMAA block length on the produced morphological structures. The resulting assemblies suggest that chain length played a minimal role in their self-assembly / Graduate / 2018-09-15

The self-assembly peptide hydrogels used as tissue culture scaffolds have drawn great attention in recent years. They have the advantages of natural polymer hydrogels including biocompatibility, biodegradability and the advantages of synthetic materials such as controlled structural properties and mechanical properties. Furthermore, the bioactive ligands which can promote bioactivities and control cell behaviours can be easily introduced to the peptide backbone through peptide synthesis. One particular self-assembly FEFEFKFK peptide was chosen in this project.FEFEFKFK peptide used in this project has been reported to self-assemble in solution, forming hydrogels with a 3D fibrous network structure above a critical gelation concentration. In this project, the self-assembly and gelation properties of FEFEFKFK peptide were further investigated, assessing the effect of pH and ionic strength on the self-assembly and gelation behaviour. The biomimetic nanofibrous hydrogels of FEFEFKFK were also assessed for their ability to support human dermal fibroblast cells. The protocols of gel preparation were developed for both 2 dimensional (2D) and 3 dimensional (3D) cell culture. A short peptide sequence homoarginine-glycine-aspartate (hRGD) has been introduced onto the amide end of the self-assembly peptide instead of bioactive ligand arginine-glycine-aspartate (RGD), creating hydrogels with a fibrous network with functionalised groups at the fibre surface. The functionalised peptide hydrogels enhanced cell adhesion on gel surface, with cell interaction assessed using various imaging and spectroscopic techniques. A preliminary 3D cell culture study also showed potential of these peptide gels to be used for encapsulated human dermal fibroblast cell studies.

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

No description available.

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.

No description available.

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)

No description available.

<p> This thesis summarizes theoretical results of two projects on the investigation of a novel organometallic polymer, the polyferrocenylsilanes(PFS). The study is carried out in collaboration with the experimental groups of Prof. Manners and Prof. Winnik at the Department of Chemistry of University of Toronto. </p> <p> In the first project, a rotational isomeric state (RIS) model is applied to study the configurational statistics of an ideal polyferrocenyldimethylsilane (PFDMS) chain: Fc[Fe(C5H4)2SiMe2]nH (Fe= Fe(C5H5)(C5H4)). The necessary conformation energies are derived from the molecular mechanics study of oligomeric (n=1,2) models for PFDMS reported by O'Hare et al.(J. Am. Chem. Soc. 1996, 118, 7578). In particular, pseudoatom and pseudobonds are introduced to describe the RIS chain of PFDMS, consistent with the special molecular geometry of the repeating ferrocene and organosilane units. The mean square unperturbed dimensions ((r^2)0, (R^2g)0), the characteristic ratios Cn(C∞) and the temperature coefficients dln (r^2)0/dT of PFDMS are calculated. The results show that an ideal PFDMS chain has a relatively low value of Coo and fast convergence of Cn to C∞ with increasing n, indicating a high static flexibility of this type of transition metal-containing polymer. The previously unknown Kuhn length of PFDMS is obtained based on the calculated C∞ </p> <p> In the second project, by taking PFS-b-PDMS/alkane as a model system, general phase behaviours of the self-assembled micelles in dilute crystalline-coil copolymer solutions (solvents are selective for the coil blocks) are investigated. Three types of aggregates - lamellar, rodlike and tubular micelles are studied based on the existing experimental observations. The computation results reveal three types of phase diagrams, namely, lamella-tube-rod phase diagrams with or without a triple point and lamella-rod phase diagrams. It is shown that lamella-tube-rod morphological transitions can be induced by changing the coil/crystalline block ratio or the temperature. Possible improvement of the theory and the current challenges of studying PFS-b-PDMS self-assembly in alkane solvents for both theories and experiments are discussed. </p> / Thesis / Master of Science (MSc)