Faculty Profiles - MASUBUCHI Yuichi

Papers - MASUBUCHI Yuichi

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Prediction of Induced Fluxes in Reverse Nonequilibrium Molecular Dynamics Reviewed International journal

Tatsuma Oishi, Yusuke Koide, Takato Ishida, Yuichi Masubuchi, Takashi Uneyama

The Journal of Chemical Physics Vol. 162 ( 5 ) 2025.2

Brownian Simulations for Fracture of Star Polymer Phantom Networks Invited Reviewed International journal

Yuichi Masubuchi, Yusuke Koide, Takato Ishida, Takashi Uneyama

Polymer Journal 2024.11

Reverse Nonequilibrium Molecular Dynamics Simulations of a Melt of Kremer-Grest Type Model under Fast Shear Reviewed International coauthorship International journal

Tatsuma Oishi, Yusuke Koide, Takato Ishida, Takashi Uneyama, Yuichi Masubuchi, Florian Müller-Plathe

Journal of Chemical Theory and Computation Vol. 20 ( 21 ) page： 9666 - 9672 2024.10

Phantom Chain Simulations for the Fracture of Star Polymer Networks with Various Strand Densities Invited Reviewed International journal

Yuichi Masubuchi, Takato Ishida, Yusuke Koide, Takashi Uneyama

Soft Matter Vol. 20 ( 36 ) page： 7103 - 7110 2024.9

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)

Fracture characteristics of phantom chain networks made from star prepolymers lie on density-dependent master curves if they are plotted against cycle rank. The density dependence cannot be explained by the modulus.

DOI： 10.1039/d4sm00726c

Polyion Hydrogels of Polymeric and Nanofibrous Carboxymethyl Cellulose and Chitosan: Mechanical Characteristics and Potential Use in Environmental Remediation Reviewed International journal

Kawate T., Wang Y., Chan K., Shibata N., Doi Y., Masubuchi Y., Zinchenko A.

Gels Vol. 10 ( 9 ) 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Gels

Recently, cellulose and other biomass nanofibers (NFs) have been increasingly utilized in the design of sustainable materials for environmental, biomedical, and other applications. However, the past literature lacks a comparison of the macromolecular and nanofibrous states of biopolymers in various materials, and the advantages and limitations of using nanofibers (NF) instead of conventional polymers are poorly understood. To address this question, hydrogels based on interpolyelectrolyte complexes (IPECs) between carboxymethyl cellulose nanofibers (CMCNFs) and chitosan (CS) were prepared by ele+ctrostatic cross-linking and compared with the hydrogels of carboxymethyl cellulose (CMC) and CS biopolymers. The presence of the rigid CMCNF altered the mechanism of the IPEC assembly and drastically affected the structure of IPEC hydrogels. The swelling ratios of CMCNF-CS hydrogels of ca. 40% were notably lower than the ca. 100–300% swelling of CMC-CS hydrogels. The rheological measurements revealed a higher storage modulus ((Formula presented.)) of the CMCNF-CS hydrogel, reaching 13.3 kPa compared to only 3.5 kPa measured for the CMC-CS hydrogel. Further comparison of the adsorption characteristics of the CMCNF-CS and CMC-CS hydrogels toward Cu2+, Cd2+, and Hg2+ ions showed the slightly higher adsorption capacity of CMC-CS for Cu2+ but similar adsorption capacities for Cd2+ and Hg2+. The adsorption kinetics obeyed the pseudo-second-order adsorption model in both cases. Overall, while the replacement of CMC with CMCNF in hydrogel does not significantly affect the performance of such systems as adsorbents, CMCNF imparts IPEC hydrogel with higher stiffness and a frequency-independent loss ((Formula presented.)) modulus and suppresses the hydrogel swelling, so can be beneficial in practical applications that require stable performance under various dynamic conditions.

DOI： 10.3390/gels10090604

Scopus

Coarse-grained Molecular Dynamics Simulation of Oxidative Aging of Polymers -effect of Free Radical Diffusivity - Invited Reviewed International journal

Takato Ishida, Yuya Doi, Takashi Uneyama, Yuichi Masubuchi

Polymer Journal 2024.8

Primitive Chain Network Simulations for Double Peaks in Shear Stress under Fast Flows of Bidisperse Entangled Polymers Invited Reviewed International journal

Masubuchi Y.

Polymers Vol. 16 ( 11 ) page： 1455-1 - 1455-10 2024.5

Authorship：Lead author,　Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Polymers

A few experiments have reported that the time development of shear stress under fast-startup shear deformations exhibits double peaks before reaching a steady state for bimodal blends of entangled linear polymers under specific conditions. To understand this phenomenon, multi-chain slip-link simulations, based on the primitive chain network model, were conducted on the literature data of a bimodal polystyrene solution. Owing to reasonable agreement between their data and our simulation results, the stress was decomposed into contributions from long- and short-chain components and decoupled into segment number, stretch, and orientation. The analysis revealed that the first and second peaks correspond to the short-chain orientation and the long-chain stretch, respectively. The results also implied that the peak positions are not affected by the mixing of short and long chains, although the intensity of the second peak depends on mixing conditions in a complicated manner.

DOI： 10.3390/polym16111455

Scopus

Dissipative Particle Dynamics Simulation Plus Slip-Springs for Entangled Polymers with Various Slip-Spring Densities Reviewed International coauthorship International journal

Yuichi Masubuchi, Hongxia Guo, Fan Wang, Bamin Khomami, Mahdi Boudaghi-Khajehnobar, Yuya Doi, Takato Ishida, Takashi Uneyama

Macromolecules Vol. 57 ( 10 ) page： 4867 - 4877 2024.5

過剰量のシランカップリング剤による鉄粒子の表面処理がMR流体のレオロジー特性に与える影響 Invited Reviewed International journal

Yuya Yamawaki, Takato Ishida, Yuya Doi, Takashi Uneyama, Yuichi Masubuchi

Nihon Reoroji Gakkaishi Vol. 52 ( 2 ) page： 99 - 105 2024.4

Authorship：Last author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Society of Rheology Japan

We investigated the effect of surface treatment for iron particles in the magnetorheological ﬂuids (MRFs) on rheological properties. Silane coupling treatment with an excess amount of dodecyltrimethoxysilane (DTMS) was conducted for iron particles. MRFs were prepared by dispersing iron particles with and without the silane coupling treatment. MRFs with iron particles washed with n-hexane after the silane coupling treatment was also prepared. The rheological properties of MRFs were measured in the presence and absence of a magnetic ﬁeld. Without a magnetic ﬁeld, MRFs with the silane-coupled particles exhibited higher stress than the untreated particles. Under a magnetic ﬁeld, MRFs with the silane-coupled particles showed lower stress than the untreated analogue. These results imply that the silane coupling treatment enhances the aggregation of particles without a magnetic ﬁeld but suppresses the cluster formation under the magnetic ﬁeld. MRFs with the washed iron particles exhibited almost the same rheological properties as that with the untreated particles. Thus we suggest that DTMS is mainly physically absorbed on the surface of iron particles, without forming chemical bonds.

DOI： 10.1678/rheology.52.99

Scopus

CiNii Research

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Anisotropy of Shear Relaxation in Primitive Chain Network Simulations for Entangled Polymers Confined between Flat Walls Invited Reviewed International journal

Masubuchi Yuichi

Nihon Reoroji Gakkaishi Vol. 52 ( 2 ) page： 77 - 82 2024.4

Authorship：Lead author,　Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：The Society of Rheology, Japan

Anisotropic shear relaxation is an interesting but rarely discussed issue in polymer dynamics under confinement. According to the earlier study of bead spring simulations for an unentangled polymer melt confined between two flat plates, the shear relaxation modulus taken perpendicular to the interface is accelerated by decreasing the distance between plates, whereas the parallel component is unchanged [Abberton et al., Macromolecules, 48, 7631, 2015]. This study observed similar anisotropic shear relaxation for entangled polymer melts under confinement in multi-chain slip-link simulations (primitive chain network simulations) for shear relaxation moduli obtained by the Green-Kubo formula. The analysis demonstrated that the accelerated relaxation in the perpendicular component reflects the Rouse-type constraint release dynamics, for which the coarsening is upper-limited by the geometry. This result suggests a novel mechanism for anisotropic shear relaxation different from the modified chain statistics under confinement considered for unentangled systems unless the obtained relaxation moduli reflect artifacts from the use of the Green-Kubo formula under confinement.

DOI： 10.1678/RHEOLOGY.52.77

Scopus

CiNii Research

Phantom Chain Simulations for Fracture of End-linking Networks Reviewed International journal

Yuichi Masubuchi

Polymer Vol. 297 page： 126880-1 - 126880-8 2024.3

Phantom chain simulations for the effect of stoichiometry on the fracture of star-polymer networks Reviewed International journal

Yuichi Masubuchi

Nihon Reoroji Gakkaishi Vol. 52 ( 1 ) page： 21 - 26 2024.2

Phantom chain simulations for fracture of polymer networks created from star polymer mixtures of different functionalities Reviewed International journal

Masubuchi Y.

Polymer Journal Vol. 56 page： 163 - 171 2023.12

Authorship：Lead author,　Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Polymer Journal

Fujiyabu et al. [1] experimentally reported that mixing of 3-arm star prepolymers into 4-arm analogs improves the toughness of the resultant polymer networks compared to that of the base network composed of only 4-arm star polymers. The present study investigated the mechanism of this phenomenon based on phantom chain simulations for polymer networks consisting of mixtures of star branch prepolymers with equal arm length and different arm numbers, (f1,f2)=(3, 4) , (3, 6) and (3, 8) , for various f1= 3 prepolymer fractions φ3 . These networks were created via end-linking reactions between prepolymers traced by a Brownian dynamics scheme, and the network structure was stored at different conversion ratios φc , ranging from 0.6 to 0.9. The cycle rank of the gelated networks ξ is entirely consistent with that given by mean-field theory, demonstrating that the examined network structure is statistically valid. The networks were stretched with energy minimization until the break, and fracture characteristics including strain at break εb , stress at break σb , work for fracture Wb , and the ratio of broken strands φbb , were obtained. Plots of εb , σb/ φbb , and Wb/ φbb versus ξ roughly follow the master curves reported for the base networks without mixing, implying that the change of fracture properties by the mixing of f1= 3 mainly corresponds to a decrease in ξ . The mixing slightly suppresses σb/ φbb and Wb/ φbb for large f2 cases compared to the base networks because of a biased breakage at the network strands without extenders, which are prepolymers with only two reacted arms. The analysis also revealed a new master curve for the ξ -dependence of the molecular weight of broken strands.

DOI： 10.1038/s41428-023-00862-w

Scopus

Modeling for Heterogeneous Oxidative Aging of Polymers Using Coarse-Grained Molecular Dynamics Reviewed International journal

Takato Ishida, Yuya Doi, Takashi Uneyama, Yuichi Masubuchi

Macromolecules Vol. 56 ( 21 ) page： 8474 - 8483 2023.11

Effects of attractive inter-particle interaction on cross-transport coefficient between mass and heat in binary fluids Reviewed International journal

Tatsuma Oishi, Yuya Doi, Yuichi Masubuchi, Takashi Uneyama

Molecular Simulation 2023.10

A Multi-Chain Slip-Spring Model without the Slip-Spring Degeneracy Reviewed International journal

Yuichi Masubuchi, Yuya Doi, Takato Ishida, Takashi Uneyama

Nihon Reoroji Gakkaishi Vol. 51 ( 4 ) page： 211 - 217 2023.10

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：The Society of Rheology, Japan

In the multi-chain slip-spring, the dynamics of Rouse chains connected by virtual springs called slip-springs that hop along the chain are considered. Although this approach has been proven to reproduce entangled polymer dynamics efficiently, the settings of the artificially introduced slip-springs should be carefully examined. In this study, we discussed the effect of the slip-spring degeneracy by limiting the number of anchored slip-springs on each Rouse bead to zero and one. According to the altered slip-spring statistics, we derived the compensation potential to eliminate the artifact of slip-springs on the chain statistics. With this potential, we performed numerical simulations. The results demonstrated that although we reasonably retain the Gaussian chain statistics, the dynamics deviate from the established entangled polymer dynamics because of the significant slow-down in the chain motion induced by the correlation between different slip-springs. The observed deceleration can be explained by the fact that the movement of slip-springs can be cast into an asymmetric exclusion process.

DOI： 10.1678/rheology.51.211

Extension of moving particle simulation by introducing rotational degrees of freedom for dilute fiber suspensions Reviewed International journal

Keigo Enomoto, Takato Ishida, Yuya Doi, Takashi Uneyama, Yuichi Masubuchi

International Journal for Numerical Methods in Fluids Vol. 96 page： 125 - 137 2023.9

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

Abstract

We develop a novel Moving Particle Simulation (MPS) method to reproduce the motion of fibers floating in sheared liquids accurately. In conventional MPS schemes, if a fiber suspended in a liquid is represented by a one‐dimensional array of MPS particles, it is entirely aligned to the flow direction due to the lack of shear stress difference between fiber–liquid interfaces. To address this problem, we employ the micropolar fluid model to introduce rotational degrees of freedom into the MPS particles. The translational motion of liquid and solid particles and the rotation of solid particles are calculated with the explicit MPS algorithm. The fiber is modeled as an array of micropolar fluid particles bonded with stretching, bending and torsional potentials. The motion of a single rigid fiber is simulated in a three‐dimensional shear flow generated between two moving solid walls. We show that the proposed method is capable of reproducing the fiber motion predicted by Jeffery's theory which is different from the conventional MPS simulations.

DOI： 10.1002/fld.5235

Scopus

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Phantom-Chain Simulations for the Effect of Node Functionality on the Fracture of Star-Polymer Networks Reviewed International journal

Yuichi Masubuchi, Yuya Doi, Takato Ishida, Naoyuki Sakumichi, Takamasa Sakai, Koichi Mayumi, Kotaro Satoh, Takashi Uneyama

Macromolecules Vol. 56 ( 23 ) page： 9359 - 9367 2023.9

Preparation and characterization of two-dimensional sheet-shaped poly(methyl methacrylate) synthesized via γ-ray polymerization in nanoclay template Invited Reviewed International journal

Yuya Doi, Mitsuo Hara, Takahiro Seki, Atsushi Takano, Takato Ishida, Takashi Uneyama, Yuichi Masubuchi

Polymer Journal Vol. 55 ( 9 ) page： 957 - 965 2023.5

Undershoots in shear startup of entangled linear polymer blends Invited Reviewed International coauthorship International journal

Parisi Daniele, Vereroudakis Emmanouil, Masubuchi Yuichi, Ianniruberto Giovanni, Marrucci Giuseppe, Vlassopoulos Dimitris

JOURNAL OF NON-NEWTONIAN FLUID MECHANICS Vol. 315 2023.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Non-Newtonian Fluid Mechanics

We revisit the transient response of entangled polymers in shear startup. Evidence from state-of-the-art experiments, modeling and simulations suggests the presence in fast flows of a weak (albeit unambiguous) undershoot, following the overshoot, i.e., while approaching the steady state. Recent sliplink simulations confirmed that the undershoot is not due to slip at the wall, and hence it is intrinsic to polymer rheology. Here, we further examine some features of the undershoot by blending two entangled homopolymers at different compositions. Since blending affects the distribution of relaxation times, it is here shown to also affect the undershoot, probably by broadening the tumbling-time distribution. Indeed, by appropriately modifying our tube-based model, that invokes tumbling to account for the undershoot, and (in parallel) by using simulations, we show how the undershoot depends on the blend composition. We map the experimental results into a diagram of terminal relaxation time versus composition, which identifies regimes where the undershoot is present. Blending is therefore proposed as a molecular mechanism to tailor the shear stress growth function signal, particularly the undershoot.

DOI： 10.1016/j.jnnfm.2023.105028

Web of Science

Scopus

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Papers - MASUBUCHI Yuichi