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論文

Layered structure in the crystalline adsorption layer and the leaching process of poly(vinyl alcohol) revealed by neutron reflectivity

宮崎 司*; 宮田 登*; 有馬 寛*; 吉良 弘*; 大内 啓一*; 笠井 聡*; 津村 佳弘*; 青木 裕之

Langmuir, 37(32), p.9873 - 9882, 2021/08

 被引用回数:0 パーセンタイル:0(Chemistry, Multidisciplinary)

We investigated the structure of the crystalline adsorption layer of poly(vinyl alcohol) (PVA) in hot water by neutron reflectivity in two cases: when the adsorption layer is exposed on the substrate by leaching the upper bulk layer and when it is deeply embedded between a relatively thick PVA film and substrate. In both cases, the PVA adsorption layer consists of three layers on the Si substrate. The bottom layer, consisting of amorphous chains that are strongly constrained on the substrate, is not swollen even in hot water at 90$$^{circ}$$C. The middle layer, consisting of amorphous chains that are much more mobile compared with those in the bottom layer, has no freedom to assume a crystalline form. Only the molecular chains in the top layer are crystallizable in the adsorption layer, leading to a heterogeneous layered structure in the film thickness direction. This layered structure is attributed to the crystallizable chains of PVA during the formation of the adsorption layer driven by hydrogen bonding. However, the structure and dynamics in the adsorption layer may differ in both cases because the molecular chains in the vicinity of the surface seem to be affected by surface effects even in the adsorption layer.

論文

Neutron reflectometry tomography for imaging and depth structure analysis of thin films with in-plane inhomogeneity

青木 裕之; 小川 紘輝*; 竹中 幹人*

Langmuir, 37(1), p.196 - 203, 2021/01

 被引用回数:0 パーセンタイル:0(Chemistry, Multidisciplinary)

Neutron reflectometry (NR) has been used for the depth structure analysis of materials at the surface and interface with a sub-nanometric resolution. Conventional NR provides averaged information for an area larger than several square centimeters; therefore, it cannot be applied to an interface with an in-plane inhomogeneity. In this study, the NR imaging of the in-plane structure of polymer thin films was achieved. The tomographic reconstruction of the spatially resolved NR profiles obtained by a sheet-shaped neutron beam provided a two-dimensional image of the in-plane interface morphology. The depth distribution of the neutron scattering length density was obtained by analyzing the position-dependent NR profile at a local area less than 0.1 mm$$^{2}$$. The current NR tomography method enables NR measurements for an interface with an inhomogeneous structure. It also provides information on the three-dimensional distribution of the atomic composition near the surface and interfaces for various materials.

論文

Water distribution in Nafion thin films on hydrophilic and hydrophobic carbon substrates

伊藤 華苗; 原田 雅史*; 山田 悟史*; 工藤 憲治*; 青木 裕之; 金谷 利治*

Langmuir, 36(43), p.12830 - 12837, 2020/11

 被引用回数:2 パーセンタイル:21.55(Chemistry, Multidisciplinary)

We performed H$$_{2}$$O and D$$_{2}$$O double contrast neutron reflectivity measurements on $$sim$$25-nm-thick Nafion thin films on hydrophilic and hydrophobic carbon in water and 80% relative humidity vapor to investigate the depth profile of the water and Nafion distribution. We found a dense Nafion layer at the air or water interface regardless of the carbon hydrophilicity. On the other hand, a water-rich Nafion dense layer was observed at the carbon interface only for hydrophilic carbon. The double contrast measurements provided quantitative information about the depth profile but simultaneously indicated that the sum of the volume occupancies of water and Nafion in the film was less than unity. We assessed the problem based on two possibilities: voids in the film or "residual water", which cannot be exchanged or is difficult to exchange with water outside.

論文

Detailed structural study on the poly(vinyl alcohol) adsorption layers on a Si substrate with solvent vapor-induced swelling

宮崎 司*; 宮田 登*; 吉田 鉄生*; 有馬 寛*; 津村 佳弘*; 鳥飼 直也*; 青木 裕之; 山本 勝宏*; 金谷 利治*; 川口 大輔*; et al.

Langmuir, 36(13), p.3415 - 3424, 2020/04

 被引用回数:6 パーセンタイル:75.63(Chemistry, Multidisciplinary)

We investigated in detail the structures in the poly(vinyl alcohol) (PVA) adsorption layers on a Si substrate, which remained on the substrate after immersing the relatively thick 30 - 50 nm films in hot water, by neutron reflectometry under humid conditions. For the PVA with a degree of saponification exceeding 98 mol %, the adsorption layer exhibits a three-layered structure in the thickness direction. The bottom layer is considered to be the so-called inner adsorption layer that is not fully swollen with water vapor. This may be because the polymer chains in the inner adsorption layer are strongly constrained onto the substrate, which inhibits water vapor penetration. The polymer chains in this layer have many contact points to the substrate via the hydrogen bonding between the hydroxyl groups in the polymer chain and the silanol groups on the surface of the Si substrate and consequently exhibit extremely slow dynamics. Therefore, it is inferred that the bottom layer is fully amorphous. Furthermore, we consider the middle layer to be somewhat amorphous because parts of the molecular chains are pinned below the interface between the middle and bottom layers. The molecular chains in the top layer become more mobile and ordered, owing to the large distance from the strongly constrained bottom layer; therefore, they exhibit a much lower degree of swelling compared to the middle amorphous layer. Meanwhile, for the PVA with a much lower degree of saponification, the adsorption layer structure consists of the two-layers. The bottom layer forms the inner adsorption layer that moderately swells with water vapor because the polymer chains have few contact points to the substrate. The molecular chains in the middle layer, therefore, are somewhat crystallizable because of this weak constraint.

論文

Elucidation of a heterogeneous layered structure in the thickness direction of poly(vinyl alcohol) films with solvent vapor-induced swelling

宮崎 司*; 宮田 登*; 浅田 光則*; 津村 佳弘*; 鳥飼 直也*; 青木 裕之; 山本 勝宏*; 金谷 利治*; 川口 大輔*; 田中 敬二*

Langmuir, 35(34), p.11099 - 11107, 2019/08

 被引用回数:10 パーセンタイル:68.76(Chemistry, Multidisciplinary)

We investigated the swelling behaviors of poly(vinyl alcohol) (PVA) films deposited on Si wafers with water vapor, which is a good solvent for PVA for elucidating structural and dynamical heterogeneities in the film thickness direction. Using deuterated water vapor, structural and dynamical differences in the thickness direction can be detected easily as different degrees of swelling in the thickness direction by neutron reflectivity. Consequently, the PVA film with a degree of saponification exceeding 98 mol % exhibits a three-layered structure in the thickness direction. It is considered that an adsorption layer consisting of molecular chains that are strongly adsorbed onto the solid substrate is formed at the interface with the substrate, which is not swollen with water vapor compared with the bulk-like layer above it. The adsorption layer is considered to exhibit significantly slower dynamics than the bulk. Furthermore, a surface layer that swells excessively compared with the underneath bulk-like layer is found. This excess swelling of the surface layer may be related to a higher mobility of the molecular chains or lower crystallinity at the surface region compared to the underneath bulk-like layer. Meanwhile, for the PVA film with a much lower degree of saponification, a thin layer with a slightly lower degree of swelling than the bulk-like layer above it can be detected at the interface between the film and substrate only under a high humidity condition. This layer is considered to be the adsorption layer composed of molecular chains loosely adsorbed onto the Si substrate.

論文

Structural approach to understanding the solubility of metal hydroxides

小林 大志*; 中嶋 翔梧*; 元川 竜平; 松村 大樹; 斉藤 拓巳*; 佐々木 隆之*

Langmuir, 35(24), p.7995 - 8006, 2019/06

 被引用回数:1 パーセンタイル:9.61(Chemistry, Multidisciplinary)

We report the hierarchical structure of zirconium hydroxide after aging at different temperatures to elucidate the factors governing zirconium solubility in aqueous solutions. Zirconium hydroxide solid phases after aging at 25, 40, 60, and 90$$^{circ}$$C under acidic to alkaline conditions were investigated using extended X-ray absorption fine structure (EXAFS) and wide- and small-angle X-ray scattering (WAXS and SAXS) techniques to reveal the bulk and surface structures of the solid phases from the nanoscale to submicroscale. After aging at 25 $$^{circ}$$C, the fundamental building unit of the solid phase was a zirconium hydroxide tetramer. The tetramers formed primary particles approximately 3 nm in size, which in turn formed aggregates hundreds of nanometers in size. This hierarchical structure was found to be stable up to 60 $$^{circ}$$C under acidic and neutral conditions and up to 40 $$^{circ}$$C under alkaline conditions. After aging at 90 $$^{circ}$$C under acidic conditions and at 60 and 90 $$^{circ}$$C under alkaline conditions, the WAXS and EXAFS measurements suggested the crystallization of the solid phase. The transformation of the solid-phase structure by temperature was discussed in relation to the solubility product to understand the solubility-limiting solid phase. The solubility of zirconium hydroxide after aging at different temperatures was governed not only by the size of the primary particles, but also by their surface configuration.

論文

Mesoscopic structures of vermiculite and weathered biotite clays in suspension with and without cesium ions

元川 竜平; 遠藤 仁*; 横山 信吾*; 小川 紘樹*; 小林 徹; 鈴木 伸一; 矢板 毅

Langmuir, 30(50), p.15127 - 15134, 2014/12

 被引用回数:21 パーセンタイル:62.52(Chemistry, Multidisciplinary)

The effect of cesium (Cs) adsorption on the mesoscopic structure of the clay minerals vermiculite and weathered biotite (WB) in suspensions was elucidated by small-angle X-ray scattering (SAXS). The clay minerals form multilayered structures and the Cs cations are strongly adsorbed in the interlayer space of the soil clays, in particular vermiculite and WB. SAXS was used to monitor the relationship between Cs adsorption at the clay interlayers and the structural changes at length scales from 0.1 to 100 nm. The variation in the distance between the neighboring clay sheets and the spatial arrangement of the clay sheets with and without Cs were clarified. Our quantitative analyses revealed that the number of stacked layers of pure vermiculite was decreased by Cs addition, whereas that of WB increased. Moreover, the average distance between the neighboring layers of vermiculite in suspension was larger than that of WB, which reflects the different conditions of Cs intercalation. These findings provide fundamental insights that are important for predicting the environmental fate of radioactive cesium in contaminated regions and for developing methods for extracting cesium from soil.

論文

Enzymatic fabrication of protein-decorated gold nanoparticles by the aid of artificial peptides with gold-binding affinity

二井手 哲平*; 下条 晃司郎; 若林 里衣*; 後藤 雅宏*; 神谷 典穂*

Langmuir, 29(50), p.15596 - 15605, 2013/12

 被引用回数:12 パーセンタイル:46.27(Chemistry, Multidisciplinary)

We report a new approach for the biofabrication of protein-immobilized gold nanoparticles (AuNPs), using oxidoreductase with gold-binding peptide-tagged recombinant proteins. First, we selected the A3 peptide as a gold binding moiety. The A3 peptide was introduced to the C-terminus of fusion proteins of immunoglobulin G (IgG)-binding domains of protein G and protein A. In the presence of the recombinant protein, the GLD-catalyzed cofactor reduction resulted in the efficient in situ fabrication of AuNPs immobilized with the fusion protein. Moreover, the protein-immobilized AuNPs were shown to have IgG binding activity. This enzyme-assisted one-pot methodology for protein-AuNPs conjugation offers one potent route for the facile fabrication of biomolecule-decorated metal NPs.

論文

Chemical modification of the internal surfaces of cylindrical pores of submicrometer size in poly(ethylene terephthalate)

前川 康成; 鈴木 康之; 前山 勝也*; 米澤 宣行*; 吉田 勝

Langmuir, 22(6), p.2832 - 2837, 2006/03

 被引用回数:6 パーセンタイル:31.21(Chemistry, Multidisciplinary)

イオン穿孔膜のナノリアクターやナノ分離膜への応用を目的として、PET膜へのイオンビーム照射により作製したイオン穿孔膜の直径が200$$sim$$800nmの微細孔について、その内壁の化学修飾法による表面特性の制御を試みた。微細孔内壁と同じ構造の膜表面をモデルとして、蛍光色素を有する4-(bromomethyl)-6,7-dimethoxy-coumarin(BrCU)を用いて、膜表面の接触角変化と蛍光強度変化よりアルキル化反応の最適条件を確定した。反応溶液を強制的に導入することで、イオン穿孔膜の微細孔内壁のアルキル化反応を試みた。その蛍光,励起スペクトルともに強度が微細孔内壁の表面積に比例して増加することから、内壁表面のアルキル化反応が進行していることがわかった。さらに、蛍光顕微鏡測定において、イオン穿孔膜の孔径210nmの微細孔に対応した位置から蛍光が観察できたことから、蛍光色素がイオン穿孔膜内に化学固定化できることが確認できた。

論文

Alternate multilayer deposition from ammonium amphiphiles and titanium dioxide crystalline nanosheets using the Langmuir-Blodgett technique

八巻 徹也; 浅井 圭介*

Langmuir, 17(9), p.2564 - 2567, 2001/05

 被引用回数:38 パーセンタイル:92.2(Chemistry, Multidisciplinary)

TiO$$_{2}$$ナノシートと有機分子から成る新規なハイブリッド多層膜をラングミュア-ブロジェット法によって作製することに成功した。層状チタン酸化合物H$$_{x}$$Ti$$_{2-x/4}$$$$_{x/4}$$O$$_{4}$$・H$$_{2}$$O (x$$sim$$0.7; □, 空孔)を剥離ゾル化した溶液上に臭化ジオクタデシルジメチルアンモニウム(DODAB)のクロロホルム溶液を展開すると、安定な単分子膜が形成された。DODAB分子とTiO$$_{2}$$ナノシートが形成したハイブリッド単分子膜は、疎水化した石英ガラス基板上に定量的に累積された。X線回折測定によると、この試料は繰り返し単位3.4 nmでアンモニウム分子とTiO$$_{2}$$が交互積層した多層膜であった。

論文

Nonlinear laser intensity dependence of the formation of carboxylic acid groupsat the surface of polymer films; The effect of coupling of radical intermediates

一ノ瀬 暢之; 玉井 聡行*; 河西 俊一; 水野 一彦*; 橋田 勲*

Langmuir, 13(10), p.2603 - 2605, 1997/00

 被引用回数:8 パーセンタイル:46.2(Chemistry, Multidisciplinary)

ポリ(4-トリメチルシリルスチレン)のスピンコート薄膜(1-1.5$$mu$$m厚)にKrFレーザー光(1-60mJcm$$^{-2}$$pulse$$^{-1}$$)を100-1000ショット照射すると膜の架橋による不溶化と表面の酸化が起こることを見い出した。一方、ポリスチレン、ポリ(4-メチルスチレン)薄膜では照射によって架橋はほとんど起こらず、酸化により易溶化した。表題高分子の酸化においてはカルボン酸が生成し、4-位の置換基が主鎖に優先して酸化されることを示した。これらのことは4-位のC-Si結合が容易にラジカル開裂し、酸化や架橋の中間体ラジカルを与えることで理解される。膜表面のカルボン酸生成量は、レーザー光強度が低い場合は強度に比例して増加するが、レーザー光強度が高いとラジカル生成密度が高いため架橋反応が進行し、カルボン酸の生成が抑えられることが分かった。

論文

Photochemical introduction of superacidic sites on fluoropolymer surfaces

一ノ瀬 暢之; 河西 俊一

Langmuir, 13(22), p.5805 - 5807, 1997/00

 被引用回数:4 パーセンタイル:73.36(Chemistry, Multidisciplinary)

四フッ化エチレン-六フッ化プロピレン共重合体(FEP)フィルムを窒素置換した亜硫酸ナトリウム水溶液と接触させ、フィルムを通してKrFレーザー光(248nm,18mJcm$$^{-2}$$pulse$$^{-1}$$)を照射した。照射フィルム表面は高い親水性を示し、XPSによる表面分析ではスルホン酸基がナトリウム塩として導入されていることが示された。フィルムを濃硫酸で処理し、ナトリウムを水素にイオン交換すると照射部分がN-ビニルカルバゾールのカチオン重合の触媒として作用することが分かった。これらのことから、本反応によりフッ素系高分子表面を強力な固体酸とすることができるものと結論された。また、フィルム表面上に超強酸サイトをパターニングできることを示した。

論文

Polymer adsorption effects on structures and rheological properties of silica suspensions

川口 正美*; 木村 吉延*; 棚橋 徹*; 竹岡 淳*; 加藤 忠哉*; 鈴木 淳市; 舩橋 達

Langmuir, 11, p.563 - 567, 1995/00

 被引用回数:36 パーセンタイル:83.06(Chemistry, Multidisciplinary)

中性子小角散乱とレオロジー的な測定により高分子溶液中のシリカサスペンションの構造を観測した。メチルセルロースの吸着はシリカ粒子をクラスター状に凝集させるが、自己相似的な構造にはならなかった。また、剪断変形率は高分子の濃度、シリカの種類により大きく変化することが示された。

論文

Effect of surfactants on the volume phase transition of cross-linked poly(acryloyl-L-proline alkyl esters)

Safranj, A.; 吉田 勝; 大道 英樹; 片貝 良一*

Langmuir, 10(9), p.2954 - 2959, 1994/00

 被引用回数:19 パーセンタイル:70.14(Chemistry, Multidisciplinary)

ポリアクリロイル-L-プロリンアルキルエステルゲル(A-ProOR:Rはメチル、エチル、プロピル)の体積相転移におよぼす各種界面活性剤の添加効果を検討した。アニオン性はカチオン性の界面活性剤の場合、体積相転移温度は界面活性剤の濃度とともに高温側に移行した。両イオン性界面活性剤の場合、体積相転移温度は移行しなかったが、低温臨界溶液温度(LCST)をはさんだ異なった温度の間での体積変化率は界面活性剤の導入によって、よりシャープになった。一方、非イオン性界面活性剤は体積相転移現象に対して何ら影響をおよぼさなかった。

論文

Surfactant effect on the inverse volume phase transition of a polymer with amino acid side chains

Safranj, A.; 吉田 勝; 大道 英樹; 片貝 良一*

Langmuir, 9(12), p.3338 - 3340, 1993/00

 被引用回数:20 パーセンタイル:89.51(Chemistry, Multidisciplinary)

インテリジェント材料創製の一環として、ポリアクリロイル-L-プロリンアルキルエステルを合成し、水系および界面活性剤を含む水系での体積相転移挙動を調べた。体積相転移温度はアルキル基のサイズが大きくなるほど低温側に移行する傾向を示した。また、ドデシル硫酸ナトリウム界面活性剤を含む水系での結果から、ポリアクリロイル-L-プロリンプロピルエステルの相転移温度が純水系では-12$$^{circ}$$C付近に存在するものと推定することができた。

論文

Study of Langmuir-Blodgett films for KrF excimer laser resist

小川 一文*; 田村 秀治*; 畑田 元義; 石原 健*

Langmuir, 4(1), p.195 - 200, 1988/01

 被引用回数:8 パーセンタイル:54.15(Chemistry, Multidisciplinary)

光感受性累積膜の製作及び微細パターンの作製を目的として5種類のジアセチレン誘導体の累積膜を作製し、KrFエキシマーレーザー光による光化学反応の研究を行った。これらの累積膜のうちで、ベンタジイノイツク酸について最も好結果が得られ、0.3$$mu$$mの分解能が得られた。このパターン生成は、1,4位置における架橋によって起こるものと考えられる。

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