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MURAKAMI Daiki

    Department of Biological and Environmental Chemistry　Lecturer
Last Updated :2024/05/15

Researcher Information

URL

ORCID ID

J-Global ID

Research Interests

  • 物理化学   バイオマテリアル   高分子化学   界面化学   

Research Areas

  • Life sciences / Biomaterials
  • Nanotechnology/Materials / Thin-film surfaces and interfaces

Academic & Professional Experience

  • 2022/04 - Today  Kindai UniversityFaculty of Humanity-Oriented Science and Engineering講師
  • 2015/04 - 2022/03  Kyushu UniversityInstitute for Materials Chemistry and Engineering助教
  • 2014/06 - 2015/03  佐賀県立九州シンクロトロン研究センター研究員
  • 2010/04 - 2014/06  科学技術振興機構ERATOプロジェクト研究員
  • 2009/04 - 2010/03  九州大学（日本学術振興会PD）研究員

Education

  • 2006/04 - 2009/03  九州大学大学院  理学府、博士後期課程
  • 2004/04 - 2006/03  九州大学大学院  理学府
  • 2000/04 - 2004/03  Kyushu University  理学部化学科

Association Memberships

  • THE CHEMICAL SOCIETY OF JAPAN   THE JAPANESE SOCIETY FOR BIOMATERIALS   THE SOCIETY OF POLYMER SCIENCE, JAPAN   

Published Papers

  • T. Kikuchi; T. Tominaga; D. Murakami; N. R. de Souza; M. Tanaka; H. Seto
    The Journal of Chemical Physics AIP Publishing 160 (6) 0021-9606 2024/02 
    Poly(ethylene oxide) (PEO) is a well-known biocompatible polymer and has widely been used for medical applications. Recently, we have investigated the dynamic behavior of hydration water in the vicinity of PEO chains at physiological temperature and shown the presence of slow water with diffusion coefficient one order of magnitude less than that of bulk water. This could be evidence for the intermediate water that is critical for biocompatibility; however, its detailed dynamical features were not established. In this article, we analyze the quasi-elastic neutron scattering from hydration water through mode distribution analysis and present a microscopic picture of hydration water as well as its relation to cold crystallization.
  • Ryohei Koguchi; Katja Jankova; Yukiko Tanaka; Aki Yamamoto; Daiki Murakami; Qizhi Yang; Bruno Ameduri; Masaru Tanaka
    Biomaterials Advances Elsevier BV 153 213573 - 213573 2772-9508 2023/10 [Refereed]
  • MD AZIZUL HAQUE; Daiki Murakami; Masaru Tanaka
    Surfaces MDPI AG 5 (3) 365 - 382 2022/07 [Refereed][Invited]
     
    Poly(2-methoxyethyl acrylate) (PMEA) is a US FDA-approved biocompatible polymer, although there is insufficient work on human umbilical vein endothelial cells (HUVECs) and platelet interaction analysis on PMEA-analogous polymers. In this study, we extensively investigated HUVEC–polymer and platelet–polymer interaction behavior by measuring the adhesion strength using single-cell force spectroscopy. Furthermore, the hydration layer of the polymer interface was observed using frequency-modulation atomic force microscopy. We found that endothelial cells can attach and spread on the PMEA surface with strong adhesion strength compared to other analogous polymers. We found that the hydration layers on the PMEA-analogous polymers were closely related to their weak platelet adhesion behavior. Based on our results, it can be concluded that PMEA is a promising candidate for the construction of artificial small-diameter blood vessels owing to the presence of IW and a hydration layer on the interface.
  • Md Azizul Haque; Daiki Murakami; Takahisa Anada; Masaru Tanaka
    Coatings 12 (6) 2022/06 [Refereed][Invited]
     
    Confluent monolayers of human umbilical vein endothelial cells (HUVECs) on a poly(2-methoxyethyl acrylate) (PMEA) antithrombogenic surface play a major role in mimicking the inner surface of native blood vessels. In this study, we extensively investigated the behavior of cell–polymer and cell–cell interactions by measuring adhesion strength using single-cell force spectroscopy. In addition, the attachment and migration of HUVECs on PMEA-analogous substrates were detected, and the migration rate was estimated. Moreover, the bilateral migration of HUVECs between two adjacent surfaces was observed. Furthermore, the outer surface of HUVEC was exam-ined using frequency-modulation atomic force microscopy (FM-AFM). Hydration was found to be an indication of a healthy glycocalyx layer. The results were compared with the hydration states of individual PMEA-analogous polymers to understand the adhesion mechanism between the cells and substrates in the interface region. HUVECs could attach and spread on the PMEA surface with stronger adhesion strength than self-adhesion strength, and migration occurred over the surface of analogue polymers. We confirmed that platelets could not adhere to HUVEC monolayers cultured on the PMEA surface. FM-AFM images revealed a hydration layer on the HUVEC surfaces, indicating the presence of components of the glycocalyx layer in the presence of intermediate water. Our findings show that PMEA can mimic original blood vessels through an antithrombogenic HUVEC monolayer and is thus suitable for the construction of artificial small-diameter blood vessels.
  • Yuka Ikemoto; Yoshihisa Harada; Masaru Tanaka; Shin-Nosuke Nishimura; Daiki Murakami; Naoya Kurahashi; Taro Moriwaki; Kosuke Yamazoe; Hitoshi Washizu; Yoshiki Ishii; Hajime Torii
    The journal of physical chemistry. B 126 (22) 4143 - 4151 2022/05 [Refereed]
     
    Elucidating the state of interfacial water, especially the hydrogen-bond configurations, is considered to be key for a better understanding of the functions of polymers that are exhibited in the presence of water. Here, an analysis in this direction is conducted for two water-insoluble biocompatible polymers, poly(2-methoxyethyl acrylate) and cyclic(poly(2-methoxyethyl acrylate)), and a non-biocompatible polymer, poly(n-butyl acrylate), by measuring their IR spectra under humidified conditions and by carrying out theoretical calculations on model complex systems. It is found that the OH stretching bands of water are decomposed into four components, and while the higher-frequency components (with peaks at ∼3610 and ∼3540 cm-1) behave in parallel with the C═O and C-O-C stretching and CH deformation bands of the polymers, the lower-frequency components (with peaks at ∼3430 and ∼3260 cm-1) become pronounced to a greater extent with increasing humidity. From the theoretical calculations, it is shown that the OH stretching frequency that is distributed from ∼3650 to ∼3200 cm-1 is correlated to the hydrogen-bond configurations and is mainly controlled by the electric field that is sensed by the vibrating H atom. By combining these observed and calculated results, the configurations of water at the interface of the polymers are discussed.
  • Mafumi Hishida; Rubaiya Anjum; Takahisa Anada; Daiki Murakami; Masaru Tanaka
    The journal of physical chemistry. B 126 (13) 2466 - 2475 2022/04 [Refereed]
     
    There is a long, ongoing debate on how small molecules (osmolytes) affect the stability of proteins. The present study found that change in collective rotational dynamics of water in osmolyte solutions likely has a dominant effect on protein denaturation. According to THz spectroscopy analysis, osmolytes that stabilize proteins are accompanied by bound hydration water with slow dynamics, while the collective rotational dynamics of water is accelerated in the case of denaturant osmolytes. Among 15 osmolytes studied here, there is a good correlation between the change in mobility in terms of water rotational dynamics and the denaturation temperature of ribonuclease A. The changes in water dynamics due to osmolytes can be regarded as a pseudo-temperature-change, which agrees well with the change in protein denaturation temperature. These results indicate that the molecular dynamics of water around the protein is a key factor for protein denaturation.
  • K. Nishida; K. Baba; D. Murakami; M. Tanaka
    Biomaterials Science 2022/04 [Refereed]
  • Taiki Tominaga; Mafumi Hishida; Daiki Murakami; Yoshihisa Fujii; Masaru Tanaka; Hideki Seto
    The journal of physical chemistry. B 126 (8) 1758 - 1767 2022/03 [Refereed]
     
    In some synthetic polymers used for medical applications, hydration water in the vicinity of the polymer chains is known to play an important role in biocompatibility and is referred to as intermediate water. The crystallization of water below 0 °C observed during thermal analysis has been considered as evidence of the presence of intermediate water. However, the origin and physicochemical properties of intermediate water have not yet been elucidated. In this study, as a typical biocompatible polymer, poly(ethylene oxide) and its hydration water were investigated with the use of terahertz time-domain spectroscopy and quasi-elastic neutron scattering. The obtained results prove the existence of a significant amount of mobile water that interacts with the polymer chains even when the water content is low at physiological temperatures.
  • Daiki Murakami; Shin-nosuke Nishimura; Yukiko Tanaka; Masaru Tanaka
    Biomaterials Advances Elsevier BV 133 112596 - 112596 2772-9508 2022/02 [Refereed]
  • Daiki Murakami; Kosuke Yamazoe; Shin-nosuke Nishimura; Naoya Kurahashi; Tomoya Ueda; Jun Miyawaki; Yuka Ikemoto; Masaru Tanaka; Yoshihisa Harada
    Langmuir American Chemical Society (ACS) 0743-7463 2022/01 [Refereed]
  • Ryongsok Chang; Evan Angelo Quimada Mondarte; Debabrata Palai; Taito Sekine; Aki Kashiwazaki; Daiki Murakami; Masaru Tanaka; Tomohiro Hayashi
    Frontiers in Chemistry 9 2021/10 [Refereed]
     
    Peptide-based self-assembled monolayers (peptide-SAMs) with specific zwitterionic amino acid sequences express an anti-biofouling property. In this work, we performed protein adsorption and cell adhesion tests using peptide-SAMs with repeating units of various zwitterionic pairs of amino acids (EK, DK, ER, and DR). The SAMs with the repeating units of EK and DK (EK and DK SAMs) manifested excellent bioinertness, whereas the SAMs with the repeating units of ER and DR (ER and DR SAMs) adhered proteins and cells. We also performed surface force measurements using atomic force microscopy to elucidate the mechanism underlying the difference in the anti-biofouling property. Our measurements revealed that water-induced repulsion with a range of about 8 nm acts between EK SAMs (immobilized on both probe and substrate) and DK SAMs, whereas such repulsion was not observed for ER and DR SAMs. The strength of the repulsion exhibited a clear correlation with the protein- and cell-resistance of the SAMs, indicating that the interfacial water in the vicinity of EK and DK SAMs is considered as a physical barrier to deter protein and cells from their adsorption or adhesion. The range of the repulsion observed for EK and DK SAMs is longer than 8 nm, indicating that the hydrogen bonding state of the interfacial water with a thickness of 4 nm is modified by EK and DK SAMs, resulting in the expression of the anti-biofouling property.
  • Tomoya Ueda; Daiki Murakami; Masaru Tanaka
    JOURNAL OF POLYMER SCIENCE WILEY 2642-4150 2021/08 [Refereed][Invited]
     
    In this study, a blood-compatible polymer, poly(2-methoxyethyl acrylate) (PMEA), was grafted onto a gold substrate with various grafting densities (sigma) (sigma = 0-0.18 chains nm(-2)), and the amount of hydrated water and mobility of the polymer chain interacting with water molecules were quantitatively evaluated using a quartz crystal microbalance with an admittance system. The amount of hydrated water decreased with increasing sigma. By contrast, the mobility of the hydrated PMEA was maximum at sigma approximate to 0.12 chains nm(-2), revealing that the amount of high-mobility water at sigma = 0.12 was higher than that at other densities. The degree of denaturation of the adsorbed fibrinogen was evaluated based on the hydrodynamic water ratio and viscoelasticity, and was found to increase with increasing sigma. The denaturation of adsorbed fibrinogen was suppressed when both the amount of hydrated water and the mobility of hydrated PMEA were high. This study demonstrates that the interfacial state of the polymer chains hydrated in water is important for blood compatibility.
  • Moe Yamazaki; Yosuke Sugimoto; Daiki Murakami; Masaru Tanaka; Tooru Ooya
    Langmuir 37 (28) 8534 - 8543 0743-7463 2021/07 [Refereed]
     
    This study focuses on dendritic glycerols and investigates the construction of biocompatible surfaces by understanding how differences in the branching of these molecules change the interactions with the biological components. The two molecules, polyglycerol dendrimer (PGD), which has a completely branched structure, and hyperbranched polyglycerol (HPG), which has an incompletely branched structure, are compared and the differences in branching are evaluated. It is shown that PGD has a little bit more intermediate water than HPG, which reflects the differences in the branching. The effect of surface state on the adsorption of the plasma proteins, human serum albumin (HSA), fibrinogen (Fib), and fibronectin (FN), is discussed by modifying a glass surface using these molecules with different hydration states. The adsorption of HSA decreases to several percent for HPG and 10% for PGD compared to unmodified substrate. Although the adsorption of Fib decreases to 5% for HPG, an increase to 150% is observed for PGD. Since this specific Fib adsorption observed only onto PGD is suppressed in the cases of a mixed solution of HSA and Fib or sequentially using HSA solution and then Fib solution, it is thought that the Vroman effect is suppressed on the PGD-modified surface. Furthermore, when AFM measurements are performed in PBS to understand the surface roughness, PGD is found to be more highly non-uniform. Because of this, the nanometer scale roughness that is significantly observed only on the PGD-modified surface is thought to have an effect on the characteristic adsorption properties of Fib. Thus, although both PGD and HPG with different branching have intermediate water, the proportion differs between PGD and HPG. Therefore, it is found that differences occur in the plasma protein adsorption mechanisms depending on the coordinates and density of hydroxyl groups within the molecules.
  • Takuma Kanamaru; Masataka Araki; Rintaro Takahashi; Shota Fujii; Toshiyuki Shikata; Daiki Murakami; Masaru Tanaka; Kazuo Sakurai
    Journal of Physical Chemistry B 125 (26) 7251 - 7261 1520-6106 2021/07 [Refereed]
     
    Poly(2-methoxyethyl acrylate) (PMEA) is known to exhibit excellent thromboresistance, i.e., hardly causing blood-clot formation on its surface. Hence, PMEA and its analogues have been commercially used for blood-contacting materials in medical devices. In this study, we investigated the conformation and solvation state of PMEA in mixtures of tetrahydrofuran (THF) and water with various water volume fractions (ϕwater) by viscosity, sedimentation equilibrium, small-angle X-ray scattering (SAXS), and dielectric relaxation measurements. We also comparatively investigated those of poly[2-(2-methoxyethoxy)ethyl methacrylate] (PMe2MA) and polystyrene (PS). For all of these, THF is a good solvent and water is a nonsolvent or poor solvent. PMe2MA and PMEA show equally good thromboresistance, while PS does not at all. The solution properties of PMe2MA and PMEA were found to be quite different from PS. There are clear attractive interactions (or correlation) between the PMEA chain (or PMe2MA) and the waters in the vicinity of the chain despite their water insolubility. These correlated waters give additional scattering and the angular dependence of SAXS was analyzed in terms of the hydration layer model that has been used in protein solution scattering. The hydration is related to increasing both the chain stiffness and excluded volume. These distinctive properties are likely related to the origin of its good thromboresistance.
  • S. Nishimura; T. Ueda; D. Murakami; M. Tanaka
    Organic Materials Georg Thieme Verlag KG 03 (02) 214 - 220 2021/04 [Refereed][Invited]
     
    Intermediate water (IW), which is formed not only by biocompatible polymers such as poly(2-methoxyethyl acrylate) (PMEA), but also by biomacromolecules, plays a key role in determining the biocompatibility of synthetic polymers. In this study, we compare the well-defined linear and cyclic PMEA using differential scanning calorimetry and atomic force microscopy. This study aims to clarify the role of the chain-end effect in IW formation to establish design guidelines for biomaterials.
  • Rubaiya Anjum; Kei Nishida; Haruka Matsumoto; Daiki Murakami; Shingo Kobayashi; Takahisa Anada; Masaru Tanaka
    Coatings 11 (4) 2021/04 [Refereed][Invited]
     
    The regulation of adhesion and the subsequent behavior of fibroblast cells on the surface of biomaterials is important for successful tissue regeneration and wound healing by implanted biomaterials. We have synthesized poly(ω-methoxyalkyl acrylate)s (PMCxAs; x indicates the number of methylene carbons between the ester and ethyl oxygen), with a carbon chain length of x = 2–6, to investigate the regulation of fibroblast cell behavior including adhesion, proliferation, migration, differentiation and collagen production. We found that PMC2A suppressed the cell spreading, protein adsorption, formation of focal adhesion, and differentiation of normal human dermal fibroblasts, while PMC4A surfaces enhanced them compared to other PMCxAs. Our findings suggest that fibroblast activities attached to the PMCxA substrates can be modified by changing the number of methylene carbons in the side chains of the polymers. These results indicate that PMCxAs could be useful coating materials for use in skin regeneration and wound dressing applications.
  • Tomoya Ueda; Daiki Murakami; Masaru Tanaka
    Colloids and Surfaces B: Biointerfaces 199 0927-7765 2021/03 [Refereed]
     
    An excellent blood-compatible polymer, poly(2-methoxyethyl acrylate) (PMEA), exhibits nanometer-scale phase-separated structures at the interface with water or phosphate-buffered saline (PBS), and fibrinogen adsorption is suppressed, especially on the water-rich region. To understand the correlation between the interfacial structure based on the grafting density of PMEA and blood compatibility, grafted PMEA (gPMEA) surfaces with controlled density were prepared by immobilizing thiol-terminated PMEA on a gold substrate. The amount of adsorbed fibrinogen and the number of adhered platelets on gPMEAs decreased first with the increasing grafting density (σ), but increased after showed minimum at σ of approximately 0.11 chains/nm . The interfacial structures of the gPMEA/PBS interface changed with grafting density, and the maximum area of water-rich region was obtained at σ = 0.11. The water contact angle at σ = 0.11 is smaller than that at the other grafting density. These results revealed that hydration to the polymer is very effective to suppress the platelet adhesion and water-rich region shows excellent blood compatibility on gPMEA surfaces. This work clearly indicated that the density of PMEA affects the interfacial structure and plays an important role in the blood compatibility of the material. 2
  • Yoshihisa Fujii; Taiki Tominaga; Daiki Murakami; Masaru Tanaka; Hideki Seto
    Frontiers in chemistry 9 728738 - 728738 2021 [Refereed]
     
    The dynamic behavior of water molecules and polymer chains in a hydrated poly(methyl methacrylate) (PMMA) matrix containing a small amount of water molecules was investigated. Water molecules have been widely recognized as plasticizers for activating the segmental motion of polymer chains owing to their ability to reduce the glass transition temperature. In this study, combined with judicious hydrogen/deuterium labeling, we conducted quasi-elastic neutron scattering (QENS) experiments on PMMA for its dry and hydrated states. Our results clearly indicate that the dynamics of hydrated polymer chains are accelerated, and that individual water molecules are slower than bulk water. It is therefore suggested that the hydration water affects the local motion of PMMA and activates the local relaxation process known as restricted rotation, which is widely accepted to be generally insensitive to changes in the microenvironment.
  • Ryohei Koguchi; Katja Jankova; Yuki Hayasaka; Daisuke Kobayashi; Yosuke Amino; Tatsuya Miyajima; Shingo Kobayashi; Daiki Murakami; Kyoko Yamamoto; Masaru Tanaka
    ACS BIOMATERIALS SCIENCE & ENGINEERING AMER CHEMICAL SOC 6 (5) 2855 - 2866 2373-9878 2020/05 [Refereed]
     
    Materials exhibiting "bio-inert properties" are essential for developing medical devices because they are less recognized as foreign substances by proteins and cells in the living body. We have reported that the presence of intermediate water (IW) with the water molecules loosely bound to a polymer is a useful index of the bio-inertness of materials. Here, we analyzed the hydration state and the responses to biomolecules of poly(2-hydroxyethyl methacrylate) (PHEMA) copolymers including small amounts of 2-(dimethylamino)ethyl methacrylate (DMAEMA) (N-series) or/and 2,2,2-trifluoroethyl methacrylate (TFEMA) (F-series). The hydration structure was analyzed by differential scanning calorimetry (DSC), the molecular mobility of the produced copolymers by temperature derivative of DSC (DDSC), and the water mobility by solid H-1 pulse nuclear magnetic resonance (NMR). Although the homopolymers did not show bio-inert properties, the binary and ternary PHEMA copolymers with low comonomer contents showed higher bio-inert properties than those of PHEMA homopolymers. The hydration state of PHEMA was changed by introducing a small amount of comonomers. The mobility of both water molecules and hydrated polymers was changed in the N-series nonfreezing water (NFW) with the water molecules tightly bound to a polymer and was shifted to high-mobility IW and free water (FW) with the water molecules scarcely bound to a polymer. On the other hand, in the F-series, FW turned to IW and NFW. Additionally, a synergetic effect was postulated when both comonomers coexist in the copolymers of HEMA, which was expressed by widening the temperature range of cold crystallization, contributing to further improvement of the bio-inert properties.
  • Mayuko Watanabe; Yukiko Tanaka; Daiki Murakami; Masaru Tanaka; Mika Kawai; Tetsu Mitsumata
    CHEMISTRY LETTERS CHEMICAL SOC JAPAN 49 (3) 280 - 283 0366-7022 2020/03 [Refereed]
     
    The effect of a magnetic field on the water contact angle for magnetic elastomers with various plasticizer contents was investigated. At a plasticizer content below 60 wt %, there was no change in contact angle when a magnetic field of 370 mT was applied. For magnetic elastomers with a plasticizer content above 65 wt %, a change in contact angle of approximately 8.0 degrees was observed (e.g. 38 degrees at 0 mT and 46 degrees at 370 mT for 65 wt % plasticizer content). Dynamic viscoelastic measurements showed that magnetic elastomers with a plasticizer content below 60 wt % demonstrate the magnetorheological (MR) effect with changes in storage modulus higher than similar to 1 MPa. Atomic force microscopy for magnetic elastomer with a plasticizer content of 50 wt % revealed that the averaged Young's modulus was 233 +/- 52.1 kPa at 370 mT and 83 +/- 5.4 kPa at 0 mT, indicating that the MR effect is caused not only on a bulk but also on a mesoscopic scale. Magnetic elastomers specialized for cell culture were obtained by optimizing the plasticizer content, that exhibit the MR effect with changes in storage modulus from 1.3 x 10(4) Pa to 9.4 x 10(5) without changing the surface properties.
  • Murakami D; Segami Y; Ueda T; Tanaka M
    Journal of biomaterials science. Polymer edition 1 - 12 0920-5063 2019/11 [Refereed]
  • Katja Jankova; Irakli Javakhishvili; Shingo Kobayashi; Ryohei Koguchi; Daiki Murakami; Toshiki Sonoda; Masaru Tanaka
    ACS Applied Bio Materials 2 (10) 4154 - 4161 2019/10 [Refereed]
     
    Copyright © 2019 American Chemical Society. The practical use of the viscous liquid polymer, poly(2-methoxyethyl acrylate) (PMEA), was expanded from thin films with excellent blood compatibility to thick coatings and free-standing films without essentially sacrificing its blood compatibility. This was undertaken by creating multiple hydrogen-bonding polymer networks by introducing a functional methacrylic monomer bearing a 6-methyl-2-ureido-4[1H]-pyrimidone group in the PMEA backbone via free radical copolymerization. The hydrogen-bonded PMEA (H-PMEA) contained about 6 mol % of the functional monomer in the copolymer. These functional monomers as physical cross-links are distributed in the PMEA matrix with a Tg of -35 °C, making H-PMEA a solid rubber-like material with recoverable tensile strain. Additionally, mechanical tests revealed its tensile strength, and thermogravimetric analyses confirmed its higher thermostability. The dry and hydration states of H-PMEA were assessed by differential scanning calorimetry, contact angle, and atomic force microscopy measurements. Comparison with viscous PMEA was made. For the first time, we included PVC alongside PET, the surface we usually use as a negative control, in the platelet adhesion test with human blood, and found out that 1.5 times more platelets adhered onto the PVC surface than onto the PET surface, while H-PMEA proved to have a clear edge. Thus, H-PMEA may serve as a suitable replacement for polymers in products contacting blood as it shows potential for making free-standing films, thick coatings, implants, and articles with various geometries for the medicinal industry.
  • Murakami D; Mawatari N; Sonoda T; Kashiwazaki A; Tanaka M
    Langmuir : the ACS journal of surfaces and colloids 35 (7) 2808 - 2813 0743-7463 2019/02 [Refereed]
  • Masaru Tanaka; Shingo Kobayashi; Daiki Murakami; Fumihiro Aratsu; Aki Kashiwazaki; Takashi Hoshiba; Kazuki Fukushima
    Bulletin of the Chemical Society of Japan 92 (12) 2043 - 2057 0009-2673 2019 [Refereed]
     
    © 2019 The Chemical Society of Japan. When biomaterials come into contact with biological fluids, water molecules immediately adsorb onto the surface of the materials. To understand the origin of the crucial roles of water molecules in biological interfaces, it is necessary to relate particular states of hydration water to various physicochemical properties of hydrated polymers. Here, advances in the inter-mediate water concept are reviewed. This account provides an overview of the progress made in the design of multi-functional biomedical polymers by controlling the bio-interfacial water states. Using principles of intermediate water, which is common in hydrated biopolymers and only biocompatible synthetic polymers, we found the synthetic methodology to create novel biocompatible polymers moves toward a more high-throughput way.
  • Ueda Tomoya; Murakami Daiki; Tanaka Masaru
    FRONTIERS IN CHEMISTRY 6 542  2296-2646 2018/11 [Refereed]
  • Daiki Murakami; Yoko Kitahara; Shingo Kobayashi; Masaru Tanaka
    ACS Biomaterials Science and Engineering 4 (5) 1591 - 1597 2373-9878 2018/05 [Refereed]
     
    © 2018 American Chemical Society. The interfacial structure of a thermosensitive biocompatible polymer, poly[2-(2-methoxyethoxy)ethyl methacrylate] (PMe2MA), at the polymer/phosphate-buffered saline (PBS) interface was investigated by atomic force microscopy. A number of nanometer scale protrusions appeared at 37 °C and disappeared at 22 °C, reversibly. This structural change occurred above the lower critical solution temperature of PMe2MA in PBS (19 °C), indicating that the formation of protrusions was explained by the microphase separation of polymer and water at the interfacial region. The protein adsorption and platelet adhesion onto PMe2MA interface were drastically restrained at 22 °C compared to that at 37 °C. Detachment of NIH3T3 cells accompanied by the dissipation of protrusions on the PMe2MA interface was also demonstrated. These results indicate that the protrusions act as the scaffold for the protein adsorption and cell adhesion.
  • Daiki Murakami; Shingo Kobayashi; Masaru Tanaka
    ACS BIOMATERIALS SCIENCE & ENGINEERING AMER CHEMICAL SOC 2 (12) 2122 - 2126 2373-9878 2016/12 [Refereed]
     
    The interfacial structures of a blood-compatible polymer, poly(2-methoxyethyl acrylate) (PMEA), and several analogues were investigated by atomic force microscopy (AFM). The blood-compatible polymers exhibited nano meter-scale protrusions that spontaneously and homogeneously formed at polymer/water and polymer/phosphatebuffered saline interfaces. AFM observation also revealed that fibrinogen adsorption occurred locally on the protrusions rather than uniformly at the interface, with the regions adjacent to the protrusions apparently preventing the adsorption of fibrinogen. The formation of these interfacial structures may be due to in-plane microphase separation of polymer and water at the interface.
  • Taiki Hoshino; Shiki Nojima; Masanao Sato; Tomoyasu Hirai; Yuji Higaki; So Fujinami; Daiki Murakami; Shigesaburo Ogawa; Hiroshi Jinnai; Atsushi Takahara; Masaki Takata
    POLYMER ELSEVIER SCI LTD 105 487 - 499 0032-3861 2016/11 [Refereed]
     
    The surface dynamics of polyhedral oligomeric silsesquioxane (POSS)-functionalized polystyrene (PS-POSS) thin films above the glass transition temperature were studied by grazing-incidence X-ray photon correlation spectroscopy in order to elucidate the effects of POSS at the end of the polystyrene chains. Much slower fluctuations were observed in the surface of PS-POSS thin films than in the polystyrene thin films, despite the negligible difference in their bulk viscosity. Quantitative analysis based on fluctuation-dissipation theorem indicated that there is a high-viscosity layer at the surface of the PS-POSS films, and that the substrate interface originated from POSS segregation. (C) 2016 Elsevier Ltd. All rights reserved.
  • Daiki Murakami; Motoyasu Kobayashi; Yuji Higaki; Hiroshi Jinnai; Atsushi Takahara
    POLYMER ELSEVIER SCI LTD 98 464 - 469 0032-3861 2016/08 [Refereed]
     
    Surface grafting of polyelectrolytes on materials brings about various significant changes in surface properties such as wettability, adhesion, and friction, because of their excellent hydrophilicity and unique intermolecular interactions that depend on the ionic strength of the solution. This review paper describes the characterization of the swollen structure and electrostatic interaction of polyelectrolyte brushes in aqueous solution by use of optical tweezers and neutron reflectivity, in order to discuss the dissociation of ionic groups and charge distribution in the polyelectrolyte brush. In addition, the spreading and structure of water on the polyelectrolyte brush surface were characterized by high spatial resolution IR spectroscopy. (C) 2016 Elsevier Ltd. All rights reserved.
  • Daiki Murakami; Yuki Norizoe; Yuji Higaki; Atsushi Takahara; Hiroshi Jinnai
    MACROMOLECULES AMER CHEMICAL SOC 49 (13) 4862 - 4866 0024-9297 2016/07 [Refereed]
     
    The phase behavior of polystyrene (PS) brushes in cyclohexane (CHX) was investigated, for the first time, by environmental atomic force microscopy as a function of the graft density and temperature. The polystyrene brushes of three different graft densities exhibited island-, bicontinuous-, and hole-shape microdomains in the direction parallel to the substrate. The size of such "in-plane" microdomains is close to the end-to-end distance of PS brush chain due to the anchoring of one of the chain ends of PS brushes to the substrate. The microdomain structure disappeared as the temperature increased, and new structure with same morphological features reappeared by lowering temperature. This reversible temperature response corresponds to the in-plane phase separation of the PS brush/CHX system. The UCST type binodal line shifted toward slightly lower temperature in the PS brush/CHX system compared to that of the corresponding nongrafted polymer solution, i.e., PS/CHX system, in excellent agreement with our previous Monte Carlo simulation study.
  • Yuji Higaki; Motoyasu Kobayashi; Daiki Murakami; Atsushi Takahara
    POLYMER JOURNAL NATURE PUBLISHING GROUP 48 (4) 325 - 331 0032-3896 2016/04 [Refereed]
     
    Polymer brushes have been utilized as a proper model interface for the investigation of wetting, lubrication, hydrated chain dimension and the structure of hydrated water at hydrated polymer interfaces. Zwitterionic polyelectrolyte-tethered surfaces represent significant anti-fouling materials for bio-macromolecules, marine fouling organisms and pipeline foulants. Systematic anti-fouling tests for various polymer brushes were performed to demonstrate the critical factors for universal anti-fouling properties. In this focused review, material design concepts and recent progress on anti-fouling polymer materials are reviewed, and our recent research on anti-fouling studies using polymer brushes is provided.
  • Takeshi Higuchi; Daiki Murakami; Hidetoshi Nishiyama; Mitsuo Suga; Atsushi Takahara; Hiroshi Jinnai
    ELECTROCHEMISTRY ELECTROCHEMICAL SOC JAPAN 82 (5) 359 - 363 1344-3542 2014/05 [Refereed]
     
    Direct observation of phenomena occurring under atmospheric conditions, especially at the nanometer scale, would offer a unique opportunity to understand the dynamics of various processes. A novel electron microscope, the atmospheric scanning electron microscope (ASEM), has recently been developed and allows for the observation of nanoscale objects under atmospheric conditions. In this paper, we present some examples of dynamic phenomena in polymer materials observed using ASEM. The first example is phase separation of a binary polymer blend upon solvent evaporation, a representative example of a non-linear non-equilibrium phenomenon in physics. Phaseseparated structures were found to appear at the final stage of solvent evaporation. Also, we found that irradiation of organic liquids (e.g., dibenzyl ether) with the ASEM electron beam induced polymerization, and the resulting material showed interesting cathodoluminescence behavior. Thus, ASEM may be useful as a tool for simultaneous polymerization and fabrication, in addition to offering a means for direct nanoscale observation of materials under atmospheric conditions. (c) The Electrochemical Society of Japan, All rights reserved.
  • Daiki Murakami; Hiroshi Jinnai; Atsushi Takahara
    LANGMUIR AMER CHEMICAL SOC 30 (8) 2061 - 2067 0743-7463 2014/03 [Refereed]
     
    The wetting transition from the Cassie-Baxter state to the Wenzel state on textured surfaces was investigated. Nano- to microscale hexagonal pillared lattices were prepared by nanoimprint lithography on fluorinated cycloolefin polymer substrates. The transition was clearly observed for water and some ionic liquids through contact angle measurements and optical microscopy. A simple model clearly demonstrated that the energy barrier in the wetting transition from the Cassie-Baxter state to the Wenzel state was dominated by the competition between the energy barrier and external forces, particularly the Laplace pressure in the present case.
  • Daiki Murakami; Ai Takenaka; Motoyasu Kobayashi; Hiroshi Jinnai; Atsushi Takahara
    LANGMUIR AMER CHEMICAL SOC 29 (52) 16093 - 16097 0743-7463 2013/12 [Refereed]
     
    We demonstrated an optical tweezers method to measure the electrostatic interaction between the strong polyelectrolyte brushes, poly(2(methacryloyloxy)ethyltrimethylammonium chloride) (PMTAC), grafted on silica particles in aqueous media. The weak electrostatic interaction was successfully detected with a resolution of less than 0.1 mu N m(-1). The apparent Debye length, including the charge distribution in the polymer brush and the surface potential, decreased as the salt concentration in the medium increased. The experimentally obtained surface charge density was much Smaller than that estimated from the amount of polyelectrolyte on the surface. Furthermore, the dissociation of ionic groups was enhanced by decreasing the grafting density of the polyelectrolyte brush. The results suggest that the majority of chloride polyelectrolyte brush layer to neutralize the high charge density. counterions was immobilized in the dense polyelectrolyte brush layer to neutralize the high charge density.
  • Taiki Hoshino; Daiki Murakami; Yoshihito Tanaka; Masaki Takata; Hiroshi Jinnai; Atsushi Takahara
    PHYSICAL REVIEW E AMER PHYSICAL SOC 88 (3) 032602  1539-3755 2013/09 [Refereed]
     
    The dynamical behavior of polystyrene-grafted silica nanoparticles dispersed in an atactic polystyrene matrix was studied using x-ray photon correlation spectroscopy. The time-autocorrelation functions were subjected to fitting analyses based on continuous-time random walk models. The nanoparticles exhibited non-Brownian behavior, and as the temperature increased, the crossover from hyperdiffusion to subdiffusion occurred at 1.25T(g), where T-g is the glass transition temperature of the matrix polystyrene. Hyperdiffusive behavior is caused by the dynamical heterogeneity of the polymer matrix associated with the glass transition. When the temperature was higher than 1.25T(g), the interaction of the grafted polymers with the polymer matrix became relatively significant, and caused a dramatic change in the dynamical behavior of the nanoparticles.
  • Takamichi Shinohara; Tomoko Shirahase; Daiki Murakami; Taiki Hoshino; Moriya Kikuchi; Jun-ichiro Koike; Misao Horigome; Hiroyasu Masunaga; Hiroki Ogawa; Atsushi Takahara
    POLYMER JOURNAL NATURE PUBLISHING GROUP 45 (3) 307 - 312 0032-3896 2013/03 [Refereed]
     
    Nanoimprint lithography (NIL) is a simple and high-resolution patterning method. Nanoimprinted structures can be fabricated not only as surface structures but also as 'buried' structures for applications such as electro-optical devices. However, a precise and nondestructive evaluation method for nanoimprinted structures has not yet been established. Synchrotron radiation ultrasmall angle X-ray scattering (SR-USAXS) is a nondestructive and high-resolution characterization method. In this study, we fabricated nanostructures on a poly(lactic acid) (PLA) film using NIL. In addition, the nanoimprinted PLA film was covered with a polystyrene thin film to fabricate a 'buried' structure. The fabricated surface and the 'buried' structure were evaluated using SR-USAXS. The scattering pattern was clearly obtained from the surface and the 'buried' structure. The size of the 'buried' structure, which was estimated from the diffraction pattern, was in good agreement with that of the surface structure. These results indicate that SR-USAXS is powerful tool for the nondestructive and precise characterization of surface and 'buried' structures. Polymer Journal (2013) 45, 307-312; doi:10.1038/pj.2012.133; published online 27 June 2012
  • Daiki Murakami; Motoyasu Kobayashi; Taro Moriwaki; Yuka Ikemoto; Hiroshi Jinnai; Atsushi Takahara
    Langmuir 29 (4) 1148 - 1151 0743-7463 2013/01 [Refereed]
     
    The wetting behavior of superhydrophilic polyelectrolyte brushes was investigated. Reflection interference contrast microscopy demonstrated that the contact angles of water on the polyelectrolyte brushes were extremely low but remained finite in the range of < 3. The presence of water molecules was evident, even outside the macroscopic water droplet. These water molecules were confined to the thin brush layers and contained a highly ordered hydrogen bond network, which was identified as structural water. The presence of the thin film and the structural water changed the surface energies, which prevented the complete wetting of the surface. © 2013 American Chemical Society.
  • Taiki Hoshino; Daiki Murakami; Kiminori Ito; Yoshihito Tanaka; Sono Sasaki; Masaki Takata; Hiroshi Jinnai; Atsushi Takahara
    POLYMER JOURNAL NATURE PUBLISHING GROUP 45 (1) 94 - 99 0032-3896 2013/01 [Refereed]
     
    The effects of a thermal gradient on the dynamical behavior of nanoparticles dispersed in a polymer matrix were studied using X-ray photon correlation spectroscopy. Polystyrene (PS)-grafted silica nanoparticles (SiNPs-PS), which are nanoparticles dispersed in a PS matrix controlled at temperatures above the glass transition temperature, were used in this study. Anisotropic motions of the SiNPs-PS were observed when the sample was kept in a conventional capillary tube, whereas isotropic motion was observed when the sample was kept in a newly designed cell with a low thermal flow, demonstrating the importance of the thermal gradient on the dynamical behavior of the SiNPs-PS. Polymer Journal (2013) 45, 94-99; doi: 10.1038/pj.2012.193; published online 21 November 2012
  • Taiki Hoshino; Moriya Kikuchi; Daiki Murakami; Yoshiko Harada; Koji Mitamura; Kiminori Ito; Yoshihito Tanaka; Sono Sasaki; Masaki Takata; Hiroshi Jinnai; Atsushi Takahara
    JOURNAL OF SYNCHROTRON RADIATION INT UNION CRYSTALLOGRAPHY 19 (Pt 6) 988 - 993 1600-5775 2012/11 [Refereed]
     
    The performance of a fast pixel array detector with a grid mask resolution enhancer has been demonstrated for X-ray photon correlation spectroscopy (XPCS) measurements to investigate fast dynamics on a microscopic scale. A detecting system, in which each pixel of a single-photon-counting pixel array detector, PILATUS, is covered by grid mask apertures, was constructed for XPCS measurements of silica nanoparticles in polymer melts. The experimental results are confirmed to be consistent by comparison with other independent experiments. By applying this method, XPCS measurements can be carried out by customizing the hole size of the grid mask to suit the experimental conditions, such as beam size, detector size and sample-to-detector distance.
  • Takahiro Yano; Yuji Higaki; Di Tao; Daiki Murakami; Motoyasu Kobayashi; Noboru Ohta; Jun-ichiro Koike; Misao Horigome; Hiroyasu Masunaga; Hiroki Ogawa; Yuka Ikemoto; Taro Moriwaki; Atsushi Takahara
    Polymer Elsevier BV 53 (21) 4702 - 4708 0032-3861 2012/09 [Refereed]
  • Motoyasu Kobayashi; Yuki Terayama; Hiroki Yamaguchi; Masami Terada; Daiki Murakami; Kazuhiko Ishihara; Atsushi Takahara
    LANGMUIR AMER CHEMICAL SOC 28 (18) 7212 - 7222 0743-7463 2012/05 [Refereed]
     
    The surface wettabilities of polymer brushes with hydrophobic and hydrophilic functional groups were discussed on the basis of conventional static and dynamic contact angle measurements of water and hexadecane in air and captive bubble measurements in water. Various types of high-density polymer brushes with nonionic and ionic functional groups were prepared on a silicon wafer by surface-initiated atom-transfer radical polymerization. The surface free energies of the brushes were estimated by Owens-Wendt equation using the contact angles of various probe liquids with different polarities. The decrease in the water contact angle corresponded to the polarity of fluoroalkyl, hydroxy, ethylene oxide, amino, carboxylic acid, ammonium salt, sulfonate, carboxybetaine, sulfobetaine, and phosphobetaine functional groups. The poly(2-perfluorooctylethyl acrylate) brush had a low surface free energy of approximately 8.7 mN/m, but the polyelectrolyte brushes revealed much higher surface free energies of 70-74 mN/m, close to the value for water. Polyelectrolyte brushes repelled both air bubbles and hexadecane in water. Even when the silicone oil was spread on the polyelectrolyte brush surfaces in air, once they were immersed in water, the oil quickly rolled up and detached from the brush surface. The oil detachment behavior observed on the superhydrophilic polyelectrolyte brush in water was explained by the low adhesion force between the brush and the oil, which could contribute to its excellent antifouling and self-cleaning properties.
  • Moyotasu Kobayashi; Yuki Terayama; Tatsuya Ishikawa; Masami Terada; Hiroe Soejima; Daiki Murakami; Atsushi Takahara
    PROGRESS IN CONTROLLED RADICAL POLYMERIZATION: MATERIALS AND APPLICATIONS AMER CHEMICAL SOC 1101 183 - + 0097-6156 2012 [Refereed]
     
    Polyelectrolytes show unique characteristics at aqueous interfaces. High-density hydrophilic polyelectrolyte brushes were prepared on Si-wafer and various substrates by surface-initiated controlled radical polymerization. Chain dimension at liquid/solid interface was characterized by neutron reflectivity. Applications of polymer brushes to super hydrophilic surface, antifouling surface, water lubrication layer and adhesion control layer are presented.
  • Atsushi Takahara; Yuki Terayama; Tatsuya Ishikawa; Masami Terada; Daiki Murakami; Moriya Kikuchi; Motoyasu Kobayashi
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY AMER CHEMICAL SOC 242 0065-7727 2011/08 [Refereed]
  • Fluorinated Langmuir monolayers are more viscous than non- fluorinated monolayers
    Daiki Murakami; Uli Langer; Ziad Khattari; Thomas Fischer
    Journal of Physical Chemistry B 114 (16) 5376 - 5379 2011/04 [Refereed]
  • Taiki Hoshino; Moriya Kikuchi; Daiki Murakami; Koji Mitamura; Yoshiko Harada; Kiminori Ito; Yoshihito Tanaka; Sono Sasaki; Masaki Takata; Atsushi Takahara
    FUTURE TRENDS IN SOFT MATERIALS RESEARCH WITH ADVANCED LIGHT SOURCES IOP PUBLISHING LTD 272 1742-6588 2011 [Refereed]
     
    X-ray photon correlation spectroscopy system was setup at SPring-8, BL19LXU, and the partial coherence scattering data from the silica particles grafted with polymer brush in polystyrene matrix were measured. Firstly, the static speckle patterns were checked. Below the glass transition temperature of polystyrene (T-g), speckles were clearly observed, on the other hand, above T-g, the scattering patterns became smooth and speckles were hardly observed. These variances of the speckle patterns result from the particle motion. Secondly, from the time variance of the speckle data, time autocorrelation functions g(2)(q,t) are calculated. While the flat behaviour of g(2)(q,t) without relaxation were observed below T-g, the relaxation behavior with relaxation time similar to 10(0)-10(1) were observed above T-g
  • Takamichi Shinohara; Tomoko Shirahase; Daiki Murakami; Taiki Hoshino; Moriya Kikuchi; Jun-ichiro Koike; Misao Horigome; Hiroyasu Masunaga; Hiroki Ogawa; Atsushi Takahara
    BURIED INTERFACE SCIENCES WITH X-RAYS AND NEUTRONS 2010 IOP PUBLISHING LTD 24 1757-8981 2011 [Refereed]
     
    Nano-imprint lithography (NIL) is a simple, low cost and high-resolution patterning method. However the precise evaluation method of nano-imprinted structure has not been established. Synchrotron radiation small angle X-ray scattering (SR-SAXS) measurement is a nondestructive and high resolution characterization method. In this study, we attempt to fabricate nanostructures on the poly(lactic acid) (PLA) film by NIL and evaluated with microscopic and scattering techniques. The mold with line/space pattern was used for NIL. Scanning electron microscope observation confirmed the formation of surface nano-structure in large areas. Also, nano-imprinted PLA film was evaluated using SR-SAXS measurement. The scattering patterns obtained from nano-imprinted PLA films were clearly observed up to higher order scattering spots. These results suggested that highly regular structure was fabricated on the surface of PLA films.
  • Daiki Murakami; Tsubasa Fukuda; Hiroki Matsubara; Makoto Aratono; Takanori Takiue
    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS ELSEVIER SCIENCE BV 354 (1-3) 205 - 209 0927-7757 2010/02 [Refereed]
     
    The interfacial tension gamma of the hexane solution of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC(10)diol) and 1H,1H,2H,2H-perfluorododecanol (TFC12OH) mixture against water was measured as a function of the total molality in and composition of TFC12OH in the mixture X-2 at 298.15 K under atmospheric pressure. The interfacial pressure pi vs. mean area per adsorbed molecule A curves and the phase diagram of adsorption (PDA) were constructed in order to shed light on the effect of the molecular orientation on the state of and the miscibility of FC(10)diol and TFC12OH in the adsorbed film. The pi vs.A curves demonstrated that the mixed system exhibits three kinds of film states, parallel-condensed, normal-condensed, and multilayer states, depending on m and X-2. The PDA indicated that film composition X-2(H) in the parallel-condensed state never exceeds 0.14 even when X-2 is increased to 0.9. This limited miscibility is probably due to a microphase separation that FC(10)diol and TFC12OH molecules are not dispersed molecularly but the parallel-condensed domains of FC(10)diol and the normal-condensed domains of TFC12OH are mixed at the interface. In the normal-condensed state, on the other hand, the FC(10)diol molecules may stand upright and be mixed with TFC12OH molecules. The multilayer is much richer in FC(10)diol than in TFC12OH when the multilayer is evolved from the parallel-condensed monolayer below X-2 = 0.9, while the fraction of TFC12OH increases very rapidly when it is evolved from the normal-condensed monolayer H above X-2=0.925. Below X-2=0.9, the X-2(H) value in the multilayer is similar to that in the parallel-condensed monolayer. Thus it is plausible that FC(10)diol molecules are preferentially piled with parallel orientation in the upper layer of the multilayer. Above X-2 = 0.925, the multilayer may not be homogeneous but heterogeneous in thickness. These views were confirmed from the X-2 dependence of molality m(i)(eq) of each component at the phase transition points. (C) 2009 Elsevier B.V. All rights reserved.
  • Takanori Takiue; Tsubasa Fukuda; Daiki Murakami; Hiroyasu Sakamoto; Hiroki Matsubara; Makoto Aratono
    JOURNAL OF PHYSICAL CHEMISTRY B AMER CHEMICAL SOC 113 (44) 14667 - 14673 1520-6106 2009/11 [Refereed]
     
    The adsorption of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC(10)diol) at the hexane solution/water interface was investigated by the measurement of interfacial tension gamma as a function of pressure p and concentration nil and the thermodynamic data analysis. The results obtained were compared with those of 1H,1H,2H,2H-perfluorodecanol (TFC10OH) in order to clarify the effect of molecular orientation on the structure and property of the adsorbed film from the viewpoint of volume change of adsorption. The interfacial pressure pi versus mean area per adsorbed molecule A curve revealed two types of phase transitions among expanded, parallel condensed, and multilayer states. The A value in the condensed state and the transition pressure between the expanded and condensed states were larger for FC(10)diol than for TFC10OH, which manifests the different molecular orientation that the dispersion interaction between hydrophobic chains is weaker in the parallel orientation of FC(10)diol than in the perpendicular orientation of TFC10OH. The partial molar volume of FC(10)diol in the condensed state (nu) over bar (H.C)(1) is slightly larger than that of TFC10OH, although the partial molar volume in the hexane solution is much smaller for FC(10)diol than for TFC10OH. This supports the view that the fluorocarbon chains of FC(10)diol remain in their contact with hexane even in the condensed film because of the parallel molecular orientation. The partial molar volume in the multilayer nu(H.M)(1) was very close to the molar volume of solid FC(10)diol nu(S)(1) and smaller than that of (nu) over bar (H.C)(1) at the condensed-multilayer phase transition, and increased gradually with molecular piling. This substantiates that FC(10)diol molecules are densely packed in a first few layers just above the phase transition and a little loosely packed in the tipper layers of the multilayer with increasing molecular piling. Furthermore, the Volume change associated with adsorption from the solid FC(10)diol Delta nu(S) evaluated from the gamma versus p curve under the existence of solid deposit was positive and showed a minimum against concentration for the multilayer state. This is primarily due to the minimum in inter-facial density at the solubility limit Gamma(H.S)(1) and thus due to the minimum in (nu) over bar (H.M)(1).
  • Takanori Takiue; Fumiya Nakamura; Daiki Murakami; Tsubasa Fukuda; Aya Shuto; Hiroki Matsubara; Makoto Aratono
    JOURNAL OF PHYSICAL CHEMISTRY B AMER CHEMICAL SOC 113 (18) 6305 - 6310 1520-6106 2009/05 [Refereed]
     
    The surface tension of the aqueous solution of 1H,1H,8H,8H-perfluorooctane-1,8-diol (FC(8)diol) was measured as a function of temperature and concentration under atmospheric pressure. The interfacial density and the entropy and energy of adsorption were evaluated and compared to those obtained for the adsorption of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC(10)diol) at the hexane solution/water interface. The surface tension curves show a break point corresponding to a phase transition of the adsorbed FC(8)diol film. The value of mean area per adsorbed molecule A just below the phase transition indicated the formation of a parallel condensed monolayer, and that above the phase transition suggested the spontaneous formation of a multilayer. The multilayer of FC(8)diol is less compressible and shows a smaller increase in layering with pi compared to FC(10)diol. This is probably because the surface force is repulsive for the hexane/FC/water interface, while it is attractive for the air/FC/water interface. The partial molar entropy change of adsorption is positive in the condensed FC(8)diol film, while it is negative in the condensed FC(10)diol film, which is reasonably explained in terms of the difference in entropy change accompanied by desolvation around the hydrophobic chain. From the viewpoints of the energetic stabilization accompanied by adsorption for the FC(8)diol system, the contribution from the replacement of air/water contact with air/fluorocarbon and fluorocarbon/water contacts and that from the molecular ordering in the adsorbed film is almost equal in case of the condensed monolayer, while in the multilayer the latter is comparatively larger than the former due to the hydrogen bonding between hydroxyl groups and the dispersion interaction among the ordered hydrophobic chains.
  • Makoto Aratono; Daiki Murakami; Hiroki Matsubara; Takanori Takiue
    JOURNAL OF PHYSICAL CHEMISTRY B AMER CHEMICAL SOC 113 (18) 6347 - 6352 1520-6106 2009/05 [Refereed]
     
    The adsorption behavior of 1, 1,2,2,-tetrahydroheptadecafluorodecanol (FC10OH), 1-eicosanol (C20OH), and their mixtures at the hexane solution/water interface is summarized briefly and examined from the viewpoints of interfacial tensions in the presence of domains, domain formation, and the correlation between the phase transition and the miscibility of film forming substances in the adsorbed films. The two-dimensional analogue of the Laplace equation showed that the interfacial tension is always higher in the presence of domains than that in the absence of them. The higher tendency of domain formation of FC10OH compared to C20OH is mainly ascribed to the excess Gibbs energy of mixing of fluorocarbon chains and hydrocarbon solvent being positive and to the interaction energy between domains being more stable against cohesion for FC10OH than for C20OH. The thermodynamic equations derived here suggested the heteroazeotropy in the phase diagram of adsorption and the temperature dependence of interfacial tension at the phase transition points, which are in accord with the experimental findings qualitatively.
  • Makoto Aratono; Kei Shimamoto; Asuka Onohara; Daiki Murakami; Hajime Tanida; Iwao Watanabe; Toru Ozeki; Hiroki Matsubara; Takanori Takiue
    ANALYTICAL SCIENCES JAPAN SOC ANALYTICAL CHEMISTRY 24 (10) 1279 - 1283 0910-6340 2008/10 [Refereed]
     
    The adsorbed film of 1-decyl-3-methylimidazolium bromide (DeMIMB) at the air/water interface was investigated employing the surface tension measurement and the x-ray absorption fine structure method under the total reflection condition (TRXAFS). From the surface tension measurement, the surface excess concentrations of ions were determined. From the XAFS measurement, two solvation states of bromide ion were found in the adsorbed film, which were assigned to be "free-Br" and "bound-Br". The hydration number of the former was estimated to be 6 while that of the latter was estimated to be 4. The results based on the XAFS analysis provided significant information on the formation of domains in the adsorbed film; the most conceivable situation is that the adsorbed molecules are definitely not homogeneously dispersed, but domains (islands or clusters) are dispersed in the adsorbed film. A regular and rather tight stacking of immidazolium rings may be formed in the domains.
  • Takanori Takiue; Tsubasa Fukuda; Daiki Murakami; Hideaki Inomata; Hiroyasu Sakamoto; Hiroki Matsubara; Makoto Aratono
    JOURNAL OF PHYSICAL CHEMISTRY C AMER CHEMICAL SOC 112 (13) 5078 - 5084 1932-7447 2008/04 [Refereed]
     
    The adsorption of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC(10)diol) at the hexane/water interface was investigated by the measurement of temperature dependence of interfacial tension and the thermodynamic data analysis in order to know the effect of two hydroxyl groups at both ends of the hydrophobic chain and the rigidity of the hydrophobic chain on the adsorption of fluorocarbon alcohol at the interface. The curves of interfacial tension versus temperature and concentration show break points corresponding to the phase transitions in the adsorbed FC10diol film. The interfacial pressure versus mean area per adsorbed molecule curve shows three kinds of states connected by two discontinuous changes. The area value after the first phase transition is very close to the calculated cross-sectional area of the FC(10)diol molecule along its major axis, and thus the FC(10)diol molecules form a condensed monolayer with molecular orientation parallel to the interface. Another noticeable point is that the value after the second phase transition point decreases furthermore to 0.12 nm(2), which is much smaller than the cross-sectional area of the fluorocarbon chain, 0.28 nm(2), with increasing interfacial pressure. This suggests that FC10diol molecules pile spontaneously and successively form a multilayer above the second phase transition. Furthermore, the partial molar entropy and energy change of adsorption in the expanded and condensed states were evaluated and compared to those of 1H,1H,2H,2H-perfluorodecanol (TFC10OH), which orients almost perpendicular to the interface. In addition to the contact of two hydroxyl groups with hexane in the bulk solution, the results are explained by the dependence of partial molar entropy and energy at the interface on the following factors resulting from the parallel orientation of FC(10)diol at the interface; (a) hydrogen bonding of two hydroxyl groups with water molecules, (b) hydrogen bonding between two hydroxyl groups facing each other, and (c) the fluorocarbon chain-water contact. The adsorbed FC(10)diol film is stabilized by factors a and b, which overwhelm the energetic disadvantage caused by factor c. Furthermore, the entropy change of adsorption Delta s in the multilayer is compared to the Delta s(cal) calculated on the assumption that the condensed monolayer piles to form the multilayer. It was suggested that FC(10)diol molecules are not so densely packed in the multilayer compared to the first condensed monolayer and therefore the multilayer is not simply formed by the piling of condensed monolayers.
  • Daiki Murakami; Takenori Fukuta; Hiroki Matsubara; Makoto Aratono; Takanori Takiue
    JOURNAL OF PHYSICAL CHEMISTRY C AMER CHEMICAL SOC 112 (12) 4564 - 4568 1932-7447 2008/03 [Refereed]
     
    The mixed adsorbed film of 1H,1H-perfluorooetanol (DFC8OH) and 1H,1H,2H,2H-perfluorodecanol (TFC10OH) at the hexane/water interface was studied on the basis of interfacial tension measurement and its thermodynamic data analysis. An adsorbed film at any composition of the mixed system as well as those of pure DFC8OH and TFC10OH systems exhibits three states: the gaseous, expanded, and condensed states. Construction of the phase diagram of adsorption clarified that DFC8OH and TFC10OH mix almost ideally in the gaseous and expanded states. On the contrary, the excess Gibbs energy of adsorption g(H,E) value evaluated in the condensed state was positive. These results are explained by considering the following two factors: (1) The mixing of binary alcohols is accompanied by the loss of dispersion interaction energy due to the difference in extent of fluorination of hydrophobic chains and in their chain length and increases the g(H,E) value. (2) Since the interchange energy concerning the interaction between dipoles with different dipole moments is negative, the mixing of these alcohols reduces the repulsive force between hydrophilic groups and thus leads to a decrease in the g(H,E) value. In the gaseous and expanded states, both of above two factors are not effective. On the other hand, the positive g(H,E) value in the condensed state is attributable to more effective dispersion interaction than the dipole-dipole interaction in short molecular distance, and so factor 1 becomes dominant. Comparison of the g(H,E) value of the present system with that of the homologous TFC10OH-TFC12OH mixture leads us to a conclusion that the hydrogenation on beta-carbons in hydrophobic chains affects appreciably the balance of interactions between hydrophilic and hydrophobic groups which governs the mixing of molecules in adsorbed films.
  • D Murakami; Y Takata; H Matsubara; M Aratono; T Takiue
    JOURNAL OF PHYSICAL CHEMISTRY B AMER CHEMICAL SOC 109 (47) 22366 - 22370 1520-6106 2005/12 [Refereed]
     
    The interfacial tension of the hexane solution of 1H,1H-perfluorononanol (FDFC9OH) and its omega-hydrogenated analogue, 1H,1H,9H-perfluorononanol (HDFC9OH), against water was measured as a function of the total molality and composition of the mixture at 298.15 K under atmospheric pressure. The existence of omega-dipole in HDFC9OH makes the interfacial density larger in the gaseous and expanded states and smaller in the condensed state compared to FDFC9OH. The phase diagram of adsorption (PDA) was constructed, and the excess Gibbs energy of adsorption (g(H,E)) was calculated at each state in order to discuss quantitatively the miscibility of FDFC9OH and HDFC9OH in the adsorbed film. We found that the g(H,E) value is negative in the gaseous state, while it is positive and increases with decreasing interfacial tension in the condensed state. These results are explained mainly by the balance of two effects induced by mixing of two alcohols: (1) Reduction of repulsive interaction between omega-dipoles aligning parallel in the adsorbed film because of the increase in mean distance between HDFC9OH molecules. (2) The loss of effective dispersion interaction between hydrophobic chains due to the fact that the oblique orientation of HDFC9OH molecules at the interface is mixed with the perpendicular one of FDFC9OH. We concluded that the factor (2) is negligible compared to the factor (1) in the gaseous and expanded films and exceeds the factor (1) in the condensed film, in which molecules are closely packed.
  • T Takiue; D Hirose; D Murakami; H Sakamoto; H Matsubara; M Aratono
    JOURNAL OF PHYSICAL CHEMISTRY B AMER CHEMICAL SOC 109 (34) 16429 - 16434 1520-6106 2005/09 [Refereed]
     
    The interfacial tension gamma of the hexane solution of 1H, 1H-perfluorononanol (FDFC9OH) and its omega-hydrogenated analogue, 1H,1H,9H-perfluorononanol (HDFC9OH), against water was measured as a function of pressure and concentration at 298.15 K in order to clarify the effect of omega-dipole on the orientation of fluorononanol molecules from the viewpoint of volume. The adsorbed films of both alcohols exhibit two kinds of phase transitions among three different states: the gaseous, expanded, and condensed states. The partial molar volume changes of adsorption nu(1)(-H) - nu(1)(O) in the expanded and condensed states were evaluated and compared between the two systems. The nu(1)(-H) - nu(1)(O) values of both alcohols are negative, and thus the alcohol molecules have smaller volume in the adsorbed film than in the bulk solution. Furthermore, the nu(1)(-H) value was obtained through the evaluation of nu(1)(O) by the density measurement of the bulk hexane solution. It was found that the nu(1)(-H) value of HDFC9OH is smaller than that of FDFC9OH in the condensed state. On the basis of three matters concerning the molecular structure of alcohols, the occupied area at the interface, and the orientation of FDFC9OH in the adsorbed film deduced from the earlier results of X-ray reflectivity measurement, the mean tilt angle of HDFC9OH from the interface normal in the condensed film was estimated to be 15 degrees. The thermodynamic estimation demonstrated here is highly valuable one to provide structure information on an adsorbed film.
  • T Takiue; D Murakami; T Tamura; H Sakamoto; H Matsubara; M Aratono
    JOURNAL OF PHYSICAL CHEMISTRY B AMER CHEMICAL SOC 109 (29) 14154 - 14159 1520-6106 2005/07 [Refereed]
     
    The interfacial tensions (gamma) of the hexane solutions of 1H,1H-perfluorononanol (FDFC9OH) and its omega-hydrogenated analogue 1H,1H,9H-perfluorononanol (HDFC9OH) against water were measured as a function of temperature and concentration under atmospheric pressure in order to know the effect of omega-dipoles on the adsorption behavior of fluorononanols. The interfacial pressure (pi) versus mean area per adsorbed molecule (A) curves consist of two discontinuous changes among three different states: the gaseous, expanded, and condensed states. The A values at given pi in the gaseous and expanded states are larger for HDFC9OH than for FDFC9OH. The changes in partial molar entropy ((u) over bar (H)(1) - (u) over bar (O)(1)) and energy ((u) over bar (H)(1) - ($) over bar (O)(1)) of adsorption were evaluated. Their values are negative, and therefore, the alcohols have a smaller entropy and energy at the interface than in the bulk solution. Furthermore, the (u) over bar (H)(1) - (u) over bar (O)(1) value is more negative for HDFC9OH than for FDFC9OH in the expanded state and also in the condensed film just above the expanded-condensed phase transition point. This seems to be due to the following: (1) HDFC9OH may tilt from interface normal for omega-dipoles to interact effectively with water molecules in the interfacial region and to reduce their own repulsive interaction between neighbors arranging parallel in the adsorbed film. This leads to a lower (u) over bar (H)(1) value for HDFC9OH than for FDFC9OH. (2) The contact of omega-dipoles with hexane molecules in the bulk solution is energetically unfavorable, and thus, the u(1)(O) value of HDFC9OH is expected to be larger than that of FDFC9OH.

Conference Activities & Talks

MISC

Industrial Property Rights

  • 高原 淳, 陣内 浩司, 村上 大樹, 乗添 祐樹  国立研究開発法人科学技術振興機構  201703013109636617

Awards & Honors

  • 2019/07 Asia Pacific Society for Materials Research Annual Meeting Award
     Analysis of interfacial structure at biocompatible polymer/water interface.
  • 2018/12 第28回日本MRS年次大会 奨励賞
     Analysis of intermediate water by Soft X-ray absorption/emission and Terahertz spectroscopy 
    受賞者: 村上大樹

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    Date (from‐to) : 2022/04 -2026/03 
    Author : 田中 賢; 安藤 幸滋; 穴田 貴久; 沖 英次; 小林 慎吾; 村上 大樹
  • ナノプレートモデルを基盤とした界面ミクロ相分離の新理論モデルの構築
    日本学術振興会：科学研究費補助金（基盤研究C）
    Date (from‐to) : 2018/04 -2021/03 
    Author : 村上大樹
  • 抗血栓性材料モデルとしての密度制御高分子ブラシの創製と水和構造解析
    公益財団法人 旭硝子財団：研究助成
    Date (from‐to) : 2018/04 -2020/03
  • 高分子電解質ブラシのイオン解離促進に向けたX線小角異常散乱法による構造解析
    日本学術振興会：科学研究費補助金（若手研究B）
    Date (from‐to) : 2015/04 -2017/03 
    Author : 村上大樹
  • 液/液界面ギブズ膜におけるドメイン構造の物理化学 -「線」の立場からの研究-
    日本学術振興会：特別研究員奨励費
    Date (from‐to) : 2008/04 -2010/03 
    Author : 村上大樹

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