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南川 卓也; 関根 由莉奈; 松村 大樹; 廣井 孝介; 高田 慎一; 神谷 嘉美*; 本多 貴之*
Langmuir, 40(11), p.5725 - 5730, 2024/03
被引用回数：0鉄と漆の化学反応を利用して、古くから黒漆が作られている。しかし、鉄と漆の反応については、ほとんど知られていない。本研究では、黒漆中のFeイオンの化学状態を、XANES, EXAFS、SAXS, SANSおよびFT-IRを使用して調査した。Fe(II)またはFe(III)を生漆に添加し、空気乾燥,加熱、またはUV照射により黒漆フィルムを作成した。これらのサンプルのXANESスペクトルの測定結果から、最初に添加したFeの酸化状態に関係なく、サンプル内のFeイオンが3価の状態で存在していることが明らかとなった。また、すべてのフィルムサンプルのEXAFSスペクトルは同様の形状であったが、ピーク強度は、空気乾燥
UV照射加熱の順に減少した。この結果は、加熱やUV照射により黒漆中のFeの配位構造が不均一になり、加熱が最も不均一になったことを示している。サンプルのFT-IRスペクトルの変化は、ウルシオールの重合挙動が空気乾燥,加熱、およびUV照射下でも異なり、漆中での反応により、Feの配位構造が不均一になることが明らかとなった。このような結果から、XANESやEXAFSスペクトルは、黒漆の情報を簡易に得る手法として有用であり、貴重な文化財の黒漆の非破壊分析に特に有効である。
後藤 亜紀*; 満汐 孝治*; 岡 壽崇; 田川 雅人*; 山下 真一*
Langmuir, 39(34), p.11954 - 11963, 2023/08
被引用回数：0 パーセンタイル：0(Chemistry, Multidisciplinary)原子状酸素(AO)は地球低軌道における残留大気の主要成分の1つであり、5eVのエネルギーで宇宙船に衝突し、高分子材料表面にナノスケールの突起を形成する。本研究では、高分子の化学構造がAOによる微細構造形成に与える影響を明らかにするため、陽電子消滅寿命測定法を用いて高分子材料の自由体積空孔サイズおよび化学変化を調べた。AO照射によって高分子両面に形成される酸化層の表面からの深さは、ポリエチレンとポリプロピレンの方がポリスチレンよりも深いことがわかった。自由体積空孔サイズはポリスチレンが最も小さく、ポリピロピレン,ポリエチレンの順に大きかったことから、高分子の自由体積空孔の大きさの違いがAOの注入深さに影響を与え、結果として酸化層の厚さや表面形状が変化したと考えられる。
Micheau, C.; 上田 祐生; 元川 竜平; Bauduin, P.*; Girard, L.*; Diat, O.*
Langmuir, 39(31), p.10965 - 10977, 2023/07
被引用回数：0 パーセンタイル：0(Chemistry, Multidisciplinary)Understanding clay flotation mechanisms has become a major concern because of the increasing level of environmental contamination of soil and ground water by heavy metals and radionuclides. Clays are often used as sorbents for extracting metals in indirect flotation processes but can function simultaneously as defoamers. However, how foam generation and stability depend on the molecular interactions between the clays and surfactant is still controversial. In the present study, an amine polyethoxylated surfactant was used as a bifunctional surfactant that collected clay particles and acted as a foaming agent in the flotation process. The pH conditions strongly affected the surfactant physicochemical properties, allowing the clay extraction efficiency to be tuned. The interfacial recovery factor of the clays almost reached 100 percent under acidic (pH lower than 6) and neutral (pH 6-10) conditions, whereas it was negative under alkaline conditions (pH higher than 10), contrary to expectations. To elucidate the mechanisms involved in the particle flotation process for each of the pH conditions, the bulk and foam phases were analyzed. The effects of electrostatic interactions between the solutes and multiscale structure on the clay extraction behavior were investigated by electrophoretic measurements, dynamic light scattering, small-angle neutron scattering, and image analysis. Based on these results, three flotation processes were found depending on pH range: surfactant foam fractionation at pH higher than 10; clay particle foam flotation at pH 6-10; and particle froth flotation at pH lower than 6.
Liu, Y.*; 宮田 登*; 宮崎 司*; 春藤 淳臣*; 川口 大輔*; 田中 敬二*; 青木 裕之
Langmuir, 39(29), p.10154 - 10162, 2023/06
被引用回数：1 パーセンタイル：52.07(Chemistry, Multidisciplinary)Water absorbed by epoxy resins from a humid atmosphere considerably influences their structure and properties. Examining the effects of absorbed water on epoxy resins at their interfaces with solid substrates is crucial because of their adhesive applications in various fields. The spatial distribution of absorbed water in epoxy resin thin films under high humidity was investigated in this study by neutron reflectometry. Water molecules were found to accumulate at the SiO
/epoxy resin interface after exposure at a relative humidity of 85% for 8 h. The formation of an ca.1 nm-thick condensed water layer was observed, and the thickness of this layer varied with curing conditions of epoxy systems. Furthermore, the water accumulation at the interface was noted to be affected by high-temperature and high-humidity environments. The formation of the condensed water layer is presumed to be related to the features of the polymer layer near the interface. The construction of the interface layer of epoxy resin would be affected by the interface constraint effect on the cross-linked polymer chain during the curing reaction. This study provides essential information for understanding the factors influencing the accumulation of water at the interface in epoxy resins. In the practical application, the process of improving the construction of epoxy resin near the interface would be a reasonable solution to resist the water accumulation in the interface.
小林 大志*; 伏見 朋和*; 水越 寛文*; 元川 竜平; 佐々木 隆之*
Langmuir, 38(48), p.14656 - 14665, 2022/12
被引用回数：2 パーセンタイル：29.84(Chemistry, Multidisciplinary)This study investigates the colloidal behavior of M(IV)(OH)
based on its zeta potential and hierarchical structure. The zeta potentials of ZrO and ThO in NaCl, NaNO
, and CaCl solutions under various pH and ionic strength conditions were measured and elucidated by a surface ionization and complexation model combined with an electric double layer. Based on the assumed similarity of the surface reactions, the model was applied to interpret the zeta potentials of Zr(OH) and Th(OH) in NaCl, NaNO, and CaCl solutions. The differences in the model parameters were deduced from the different origins of M(IV)(OH) formed by hydrolysis reactions. The size distributions of the selected Zr(OH) suspensions measured by dynamic light scattering techniques suggest that the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory governs the colloidal behavior of large aggregates. Additionally, the small angle X-ray scattering measurements elucidated the structure of Zr(OH) in the nanometer scale. The primary and secondary particle sizes were found to be more dependent on the ionic strength of the electrolyte solutions than on the zeta potentials. The direct interaction of counter ions may affect the formation of primary and secondary particles with comparable size ranges.
下北 啓輔*; 山本 勝宏*; 宮田 登*; 有馬 寛*; 中西 洋平*; 竹中 幹人*; 柴田 基樹*; 山田 悟史*; 瀬戸 秀樹*; 青木 裕之; et al.
Langmuir, 38(41), p.12457 - 12465, 2022/10
被引用回数：0 パーセンタイル：0(Chemistry, Multidisciplinary)We measured the neutron reflectivity (NR) of isotactic polypropylene (PP) thin films deposited on Si substrates modified by hexamethyldisilazane (HMDS) at the saturated vapor pressure of deuterated water at 25
C and 60C/85% RH to investigate the effect of HMDS on the interfacial water accumulation in PP-based polymer/inorganic filler nanocomposites and metal/resin bonding materials. We found that the amount of water accumulated at the PP/Si interface decreased with increasing immersion time of the Si substrate in a solution of HMDS in hexane prior to PP film deposition. During the immersion of the Si substrate, the HMDS molecules were deposited on the Si substrate as a monolayer without aggregation. Furthermore, the coverage of the HMDS monolayer on the Si substrate increased with increasing immersion time. At 60C and 85% RH, only a slight amount of interfacial water was detected after HMDS treatment for 1200 min. As a result, the maximum concentration of interfacial water was reduced to 0.1 from 0.3, where the latter corresponds to the PP film deposited on the untreated substrate.
垣内 拓大*; 的場 友希*; 小山 大輔*; 山本 優貴*; 吉越 章隆
Langmuir, 38(8), p.2642 - 2650, 2022/03
被引用回数：1 パーセンタイル：14.86(Chemistry, Multidisciplinary)Hf薄膜を形成したSi(111)基板の界面および表面の酸化プロセスを超音速酸素分子ビーム(SOMB)と放射光光電子分光法により研究した。酸化は最表面のHf層から始まり、化学量論的なHfOを生成する。2.2eVのSOMBを照射した場合、界面のHfシリサイドが酸化され、HfO/Si界面近傍にHf-O-Siが生成した。Si基板で酸化が起こり、SiO化合物が生成される。HfO層の下にあるSiO/Si界面領域からSi原子が放出され、歪んだSi層に発生した応力を解放する。放出されたSi原子は、HfOを通過して入射するOガスと反応する。
和泉 篤士*; 首藤 靖幸*; 柴山 充弘*; 宮田 登*; 宮崎 司*; 青木 裕之
Langmuir, 37(47), p.13867 - 13872, 2021/11
被引用回数：2 パーセンタイル：14.88(Chemistry, Multidisciplinary)The structural formation mechanism of phenolic resin-silica interfaces was investigated in situ by neutron reflectometry during curing. There was a 4 nm thick novolac resin adsorption layer on the silica surface before curing. The curing reaction of the novolac resin with hexamethylenetetramine (HMTA) increased the coherent neutron scattering length density of the resin due to the cure shrinkage accompanied by the volatilization of ammonia, which is a byproduct of HMTA decomposition. As curing proceeded at 180C, the thickness of the bulk layer increased despite the cure shrinkage, and the thickness of the interfacial layer decreased from 4 to 1 nm. This is attributed to the diffusion of decomposed HMTA fragments generated in the bulk layer into the interfacial novolac adsorption layer during diffusion throughout the bulk layer, incorporating the upper part of the interfacial layer reacting with the fragment into the bulk layer. On the other hand, the fragments could not diffuse into the tightly bound immobile segments of novolac resin in direct contact with the silica surface, retaining the 1-2 nm thick interfacial layer in the cured resin. This structural formation mechanism caused interfacial cross-link inhomogeneity in the cured resin on the silica surface.
(001) surface using supersonic seeded oxygen molecular beam勝部 大樹*; 大野 真也*; 高柳 周平*; 尾島 章輝*; 前田 元康*; 折口 直紀*; 小川 新*; 池田 夏紀*; 青柳 良英*; 甲谷 唯人*; et al.
Langmuir, 37(42), p.12313 - 12317, 2021/10
被引用回数：1 パーセンタイル：6.77(Chemistry, Multidisciplinary)超音速分子ビーム(SSMB)を用いて、アナターゼ型TiO(001)表面の酸素空孔の酸化を調べた。SSMBによって表面およびサブサーフェイスの酸素空孔を除去できた。格子間空孔が酸素空孔の大部分と考えられるが、SSMBによって効果的に除去できた。表面の酸素空孔は、TiO結晶成長後の状態では安定であるが、SSMBを用いて同様に効果的に除去できた。
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：5 パーセンタイル：38.19(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 90C. 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.
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：2 パーセンタイル：14.88(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
. 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.
宮崎 司*; 下北 啓輔*; 山本 勝宏*; 青木 裕之; 山田 悟史*; 宮田 登*
Langmuir, 36(49), p.15181 - 15188, 2020/12
被引用回数：6 パーセンタイル：31.74(Chemistry, Multidisciplinary)We investigated the polymer chain dynamics in a 2-3 nm thick poly(vinyl acetate) (PVAc) adsorption layer on a Si substrate with a native oxide layer via neutron reflectometry combined with toluene vapor-induced swelling. We can investigate the polymer chain dynamics difference in the film thickness direction by the difference in the degree of swelling of the polymer layers detected by neutron reflectometry. The mobility of the polymer chains depends on the distance from the substrate. The results elucidated that the interfacial layer with a thickness of approximately 1 nm did not swell at all with toluene vapor, which is a solvent for PVAc. Meanwhile, the surface layer excessively swells with toluene vapor compared to the bulk. This indicates that the polymer chain within the interfacial region is immobilized by the substrate through hydrogen-bonding interaction, but in the surface region, the surface effect overcomes this interfacial interaction. We concluded that the polymer chains in the adsorption layer are either strongly constrained to the substrate, owing to hydrogen bonding, or more mobile than the bulk, owing to the surface effect.
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：13 パーセンタイル：58.64(Chemistry, Multidisciplinary)We performed HO and DO double contrast neutron reflectivity measurements on 
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.
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：14 パーセンタイル：58.64(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.
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：22 パーセンタイル：67.64(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.
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：5 パーセンタイル：22.5(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 90C 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 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 C under acidic and neutral conditions and up to 40 C under alkaline conditions. After aging at 90 C under acidic conditions and at 60 and 90 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.
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：27 パーセンタイル：62.29(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.
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：13 パーセンタイル：44.11(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.
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：30.05(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200800nm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。
八巻 徹也; 浅井 圭介*
Langmuir, 17(9), p.2564 - 2567, 2001/05
被引用回数：41 パーセンタイル：92.2(Chemistry, Multidisciplinary)TiO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
Ti
□
O・HO (x0.7; □, 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が交互積層した多層膜であった。
