東京大学 · 材料科学
横山秀明教授の研究室では、ブロックコポリマーの自己組織化とナノ構造の制御を核に、スパッタリング法や超臨界二酸化炭素を用いたナノセルラ構造の創出、および表面・界面における分子配向の精密制御を追求しています。特に、ポリスチレン-ブロック-2-ビニルピリジン系やフッ素化ブロックコポリマーを用いたナノスケールの周期的構造形成や、超臨界CO2を用いたナノセルの均一な形成メカニズムの解明が特徴です。表面・界面における分子の選択的配向とその動的挙動の評価にも強みを持ち、表面改質やナノマテリアルの開発に応用可能な基盤技術の構築を目指しています。
Figures are computed from collected data and may differ slightly.
The structure of asymmetric poly(styrene-b-2-vinylpyridine) (PS-PVP) diblock copolymers allowed to order in a thin film is observed by a combination of secondary ion mass spectrometry and scanning force microscopy. The surface/interface-induced ordering persists over a surprisingly long range (more than 1 μm). The 2-D structure in the layer parallel to a surface is mainly a distorted hexagonal structure similar to that of the (110) plane of a body-centered cubic structure. In contrast to the lon
Uniform nanocellular structures are successfully formed within the spherical nanodomains of CO2-philic fluorinated blocks in Poly[styrene-block-4-(perfluorooctylpropyloxy)styrene] (PS−PFS) and Poly[styrene-block-perfluorooctylethyl methacrylate] (PS−PFMA) monoliths using supercritical (SC) carbon dioxide (CO2). The nanocells have a very small surface area, indicative of the closed cell structure. Temperature of depressurization (Td) is the key to the uniform nanocellular formation in the CO2-phi
The temperature and molecular weight dependence of the self-diffusion coefficient of asymmetric diblock copolymers (polystyrene-b-2-vinylpyridine) (PS−PVP) with a spherical PVP domain structure has been measured by forward recoil spectrometry. The self-diffusion coefficient D is decreased by up to a factor of 10-4 by the existence of the ordered spherical microstructure. The normalized diffusion coefficient D/D0, where D0 is the diffusion coefficient of homopolystyrene with same molecular weight
A novel, facile, and reproducible method of fabricating nanocells in thin films (see Figure) has been developed using a fluorinated block copolymer with a supercritical carbon dioxide (scCO2) soluble block as a template. The nanocells have an average spacing of 34 nm and a number density of 9 × 1010 cm–2. The size of nanocellular structures is readily tunable by changing the saturation pressure of scCO2.
A block copolymer of deuterated polystyrene (dPS) and 2-[2-(2-methoxyethoxy)ethoxy]ethyl methacrylate (PME3MA) spontaneously exposes the PME3MA block, which is soluble in water, to the surface in a vacuum. dPS−PME3MA mixed with polystyrene (PS) segregates to the PS surface and changes the hydrophobic PS surface into hydrophilic surface. Neutron reflectivity, X-ray photoelectron spectroscopy, and dynamic secondary ion mass spectrometry probe the surface segregation of dPS−PME3MA to the surface of
The morphology and self-diffusion in thin films of asymmetric polystyrene-b-2-vinylpyridine (PS−PVP) diblock copolymers were investigated by secondary ion mass spectrometry (SIMS). An oscillatory depth profile of the PVP volume fraction is observed, implying a periodic arrangement of layers of PVP spherical domains organized parallel to the silicon substrate that persisted for films as thick as at least 200 nm (6 layers). The period of the PVP volume fraction oscillation is reasonably close to t
Surface structures of asymmetric poly[styrene-block-4-(perfluorooctylpropyloxy)styrene] block copolymers (PS−PF) with the shorter PF block than the PS block have been investigated using X-ray photoelectron spectroscopy (XPS) and dynamic secondary ion mass spectrometry (SIMS). Fluorooctyl side groups (C8F17) of the block copolymers segregate to the surface due to their low surface energy. Asymmetry of the block remarkably influences the structure of the C8F17 side groups and the backbone of PS−PF
Self-diffusion and tracer diffusion (diffusion in a fixed diblock copolymer matrix) of ABA triblock copolymers of styrene and 2-vinylpyridine (PVP-PS-PVP) have been measured in a spherically ordered domain structure and compared to that of diblock copolymers. In most of the cases, the self-diffusion and tracer diffusion of the triblock copolymer is controlled by a “walking” diffusion mechanism in which one PVP end block is activated at a time, giving rise to an exponential decrease in D/D0 as ex
Small capsules: Nanoscale silica capsules can be synthesized by the oxidation of nanoscale bubbles in the poly(dimethylsiloxane) domains of poly(styrene-b-dimethylsiloxane). These nanobubbles are introduced by a process involving supercritical carbon dioxide. The nanocapsules are opened up after dry etching (see AFM image).
This paper reports the appearance of a unique foam structure and pressure-induced order–order transition (OOT) of semifluorinated block copolymers in supercritical carbon dioxide (scCO2). The morphological transition of block copolymers with the fluorinated block in scCO2 is induced by the increasing apparent volume fraction of the fluorinated domain, which is preferentially swollen with CO2. The poly(styrene-b-perfluorooctylethyl methacrylate) (PS-PFMA) and PS-PFMA/homoPS blend were swollen wit
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