散乱法を用いたスピノーダル分解における高分子混合系の自己組織化過程に関する研究

京都大学0048新制・課程博士博士(工学)甲第5240号工博第1269号新制||工||896(附属図書館)UT51-93-B290京都大学大学院工学研究科高分子化学専攻(主査)教授 川端 季雄, 教授 梶 慶輔, 教授 山本 雅英学位規則第4条第1項該当Doctor of EngineeringKyoto UniversityDFA

Correlating the structures and photovoltaic properties in phase-separated blends of conjugated donor polymers and acceptors

The power conversion efficiency of polymer solar cells strongly depends on the microscale morphology of the interpenetrating network structures between the polymer donor and acceptor materials. Therefore, it is essential to understand the relationship between photovoltaic properties and phase-separated structures in the blend active layer. Here, we discuss the relationship between charge generation and collection and phase-separated structures, which was analyzed by a ternary phase diagram for polymer solar cells based on blends of a thiophene-based conjugated polymer donors and the following different acceptors: a fullerene derivative, a nonfullerene acceptor, and a conjugated polymer acceptor. By considering the ternary phase diagram based on the Flory–Huggins interaction parameters, we discuss the binodal point and acceptor volume fraction in the mixed phase in each material combination. Furthermore, we suggest strategies for improving the efficiency of polymer solar cells according to the molecular weight of acceptor materials. These findings will provide a guideline for developing highly efficient polymer solar cells

Primordial Magnetic Field from Gravitationally Coupled Electrodynamics in Bouncing Scenario

We in this paper study the generation of primordial magnetic field (PMF) in the non-singular bouncing scenario, through the coupling of the electromagnetic field to gravity. We adopt an electrodynamic model with a coupling coefficient as a function of the scale factor $a$, i.e. $f=1+(a/a_\star)^{-n}$, with $a_\star$ and $n>0$ being constants. The result implies that in this mechanism, the power spectrum of PMF today is always blue tilted on large scales from $1$ Mpc to the Hubble length, and the observational constraints favor the ekpyrotic-bounce scenario. Furthermore, the back reaction of the energy density of PMF at the bouncing point yields theoretical constraints on the bouncing model

Influence of microstructural variations on morphology and separation properties of polybutadiene-based polyurethanes

Polybutadiene-based polyurethanes with different cis/trans/1, 2-vinyl microstructure contents are synthesized. The phase morphology and physical properties of the polymers are investigated using spectroscopic analysis (FTIR and Raman), differential scanning calorimetry (DSC), X-ray scattering (WAXD and SAXS) and atomic force microscopy (AFM). In addition, their gas transport properties are determined for different gases at 4 bar and 25 °C. Thermodynamic incompatibility and steric hindrance of pendant groups are the dominant factors affecting the morphology and properties of the PUs. FTIR spectra, DSC, and SAXS analysis reveal a higher extent of phase mixing in high vinyl-content PUs. Moreover, the SAXS analysis and AFM phase images indicate smaller microdomains by increasing the vinyl content. Smaller permeable soft domains as well as the lower phase separation of the PUs with higher vinyl content create more tortuous pathways for gas molecules and deteriorate the gas permeability of the membranes

Induction of functional xeno-free MSCs from human iPSCs via a neural crest cell lineage

iPS細胞から間葉系幹細胞の誘導方法を確立 --動物由来成分を含まず再生医療への利用に期待. 京都大学プレスリリース. 2022-09-15.A new method for inducing mesenchymal stem cells from iPS cells without using animal-derived components. 京都大学プレスリリース. 2022-09-27.Mesenchymal stem/stromal cells (MSCs) are adult multipotent stem cells. Here, we induced MSCs from human induced pluripotent stem cells (iPSCs) via a neural crest cell (NCC) lineage under xeno-free conditions and evaluated their in vivo functions. We modified a previous MSC induction method to work under xeno-free conditions. Bovine serum albumin-containing NCC induction medium and fetal bovine serum-containing MSC induction medium were replaced with xeno-free medium. Through our optimized method, iPSCs differentiated into MSCs with high efficiency. To evaluate their in vivo activities, we transplanted the xeno-free-induced MSCs (XF-iMSCs) into mouse models for bone and skeletal muscle regeneration and confirmed their regenerative potency. These XF-iMSCs mainly promoted the regeneration of surrounding host cells, suggesting that they secrete soluble factors into affected regions. We also found that the peroxidasin and IGF2 secreted by the XF-iMSCs partially contributed to myotube differentiation. These results suggest that XF-iMSCs are important for future applications in regenerative medicine

Self-assembling in gelation processes of NIPAAM gel(Soft Matter as Structured Materials)

この論文は国立情報学研究所の電子図書館事業により電子化されました。ポリN-イソプロピルアクリルアミド(NIPAAM)/水系は曇点を32℃に持つLCST型の相図を有する。その為にNIPAAMゲルの形成過程は合成温度に強く依存する事が予想される。例えば合成温度が32℃より高い時には、NIPAAMゲルはマクロ相分離とゾルーゲル転移が競合しながら形成されるため、ゲルの内部構造はマクロ相分離構造を内包した階層構造を取ると予想される。本研究では様々な合成温度におけるNIPAAMゲルの合成過程における内部構造の形成機構を、時分割超小角X線散乱法(USAXS法)および時分割小角X線散乱法(SAXS法)により調べた結果について報告する

Directed self-assembly of block copolymers

Block copolymers in the strong segregation regime self-assemble to form regular periodic nanopatterns that are applicable as templates for nanofabrication or nanoprocessing such as etching masks for nanolithography. However, self-assembly of block copolymers alone usually results in poly-grain structures. Directed self-assembly is an excellent technique developed rapidly in the past decade. Directed self-assembly either by graphoepitaxy with topographical guides or chemical registration with chemically pattered surfaces enabled us to control orientation and alignment of block copolymer microdomains in thin film on a substrate. It is expected that this technique will further extend the resolution limit of the conventional photolithography. This article briefly review the directed self-assembly techniques