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Ikeda T, Kobayashi Y, Yamakawa M. Structure and dynamics of amphiphilic patchy cubes in a nanoslit under shear. J Chem Phys 2024; 161:024901. [PMID: 38973760 DOI: 10.1063/5.0216550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 06/17/2024] [Indexed: 07/09/2024] Open
Abstract
Patchy nanocubes are intriguing materials with simple shapes and space-filling and multidirectional bonding properties. Previous studies have revealed various mesoscopic structures such as colloidal crystals in the solid regime and rod-like or fractal-like aggregates in the liquid regime of the phase diagram. Recent studies have also shown that mesoscopic structural properties, such as an average cluster size M and orientational order, in amphiphilic nanocube suspensions are associated with macroscopic viscosity changes, mainly owing to differences in cluster shape among patch arrangements. Although many studies have been conducted on the self-assembled structures of nanocubes in bulk, little is known about their self-assembly in nanoscale spaces or structural changes under shear. In this study, we investigated mixtures of one- and two-patch amphiphilic nanocubes confined in two flat parallel plates at rest and under shear using molecular dynamics simulations coupled with multiparticle collision dynamics. We considered two different patch arrangements for the two-patch particles and two different slit widths H to determine the degree of confinement in constant volume fractions in the liquid regime of the phase diagram. We revealed two unique cluster morphologies that have not been previously observed under bulk conditions. At rest, the size of the rod-like aggregates increased with decreasing H, whereas that of the fractal-like aggregates remained constant. Under weak shear with strong confinement, the rod-like aggregates maintained a larger M than the fractal-like aggregates, which were more rigid and maintained a larger M than the rod-like aggregates under bulk conditions.
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Affiliation(s)
- Takahiro Ikeda
- Faculty of Mechanical Engineering, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Yusei Kobayashi
- Faculty of Mechanical Engineering, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Masashi Yamakawa
- Faculty of Mechanical Engineering, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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2
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Kobayashi Y, Gomyo H, Arai N. Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow. Int J Mol Sci 2021; 22:ijms22147573. [PMID: 34299196 PMCID: PMC8307477 DOI: 10.3390/ijms22147573] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/03/2021] [Accepted: 07/12/2021] [Indexed: 11/16/2022] Open
Abstract
The phenomenon of drag reduction (known as the “Toms effect”) has many industrial and engineering applications, but a definitive molecular-level theory has not yet been constructed. This is due both to the multiscale nature of complex fluids and to the difficulty of directly observing self-assembled structures in nonequilibrium states. On the basis of a large-scale coarse-grained molecular simulation that we conducted, we propose a possible mechanism of turbulence suppression in surfactant aqueous solution. We demonstrate that maintaining sufficiently large micellar structures and a homogeneous radial distribution of surfactant molecules is necessary to obtain the drag-reduction effect. This is the first molecular-simulation evidence that a micellar structure is responsible for drag reduction in pipe flow, and should help in understanding the mechanisms underlying drag reduction by surfactant molecules under nonequilibrium conditions.
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Correia EL, Brown N, Razavi S. Janus Particles at Fluid Interfaces: Stability and Interfacial Rheology. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:374. [PMID: 33540620 PMCID: PMC7913064 DOI: 10.3390/nano11020374] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 01/26/2021] [Accepted: 01/29/2021] [Indexed: 02/08/2023]
Abstract
The use of the Janus motif in colloidal particles, i.e., anisotropic surface properties on opposite faces, has gained significant attention in the bottom-up assembly of novel functional structures, design of active nanomotors, biological sensing and imaging, and polymer blend compatibilization. This review is focused on the behavior of Janus particles in interfacial systems, such as particle-stabilized (i.e., Pickering) emulsions and foams, where stabilization is achieved through the binding of particles to fluid interfaces. In many such applications, the interface could be subjected to deformations, producing compression and shear stresses. Besides the physicochemical properties of the particle, their behavior under flow will also impact the performance of the resulting system. This review article provides a synopsis of interfacial stability and rheology in particle-laden interfaces to highlight the role of the Janus motif, and how particle anisotropy affects interfacial mechanics.
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Affiliation(s)
| | | | - Sepideh Razavi
- School of Chemical, Biological, and Materials Engineering, University of Oklahoma, 100 E. Boyd Street, Norman, OK 73019, USA; (E.L.C.); (N.B.)
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Kobayashi Y, Arai N, Nikoubashman A. Structure and Shear Response of Janus Colloid-Polymer Mixtures in Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:14214-14223. [PMID: 33207880 DOI: 10.1021/acs.langmuir.0c02308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate the structure and rheological properties of dilute colloid-polymer mixtures at rest and under shear via molecular simulations that take into account hydrodynamic interactions. Mixtures of amphiphilic Janus colloids (JCs) and hydrophobic/amphiphilic polymers are considered for various solvent qualities and polymer concentrations. Free polymers, small polymer droplets, and hybrid aggregates coexist in mixtures with slightly hydrophobic homopolymers. As the solvent quality worsens, all polymers aggregate into small droplets, covered and stabilized by the JCs. In mixtures with amphiphilic polymers, we observe the coexistence of free polymers, purely polymeric micelles, and hybrid aggregates. At low shear rates, all mixtures exhibit a Newtonian-like response with intrinsic shear viscosities that are up to 2 times as large as of pure suspensions of nonadsorbing colloids at the same concentration. Furthermore, the mean aggregation number increases slightly due to the flow-enhanced collision of aggregates. At larger shear rates, however, the aggregates break up, the polymers align in the flow direction, and the mixtures exhibit shear-thinning. This shear-induced breakup occurs at stronger shear compared to pure JC suspensions, indicating that the adsorbed polymers reinforce the hybrid aggregates.
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Affiliation(s)
- Yusei Kobayashi
- Department of Mechanical Engineering, Keio University, Kohoku-ku, 223-8522 Yokohama, Japan
| | - Noriyoshi Arai
- Department of Mechanical Engineering, Keio University, Kohoku-ku, 223-8522 Yokohama, Japan
| | - Arash Nikoubashman
- Department of Mechanical Engineering, Keio University, Kohoku-ku, 223-8522 Yokohama, Japan
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
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Tsujinoue H, Kobayashi Y, Arai N. Effect of the Janus Amphiphilic Wall on the Viscosity Behavior of Aqueous Surfactant Solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:10690-10698. [PMID: 32804514 DOI: 10.1021/acs.langmuir.0c01359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The effects of the chemical nature of an interface are one of the key parameters which can affect self-assembly and rheological behavior. To date, several studies have reported self-assembled structures and rheological behaviors in the development of various functional materials. In this study, we investigated the self-assembly and viscosity behavior of aqueous surfactant solutions confined in three types of Janus amphiphilic nanotubes (JANTs), which have two, four, and eight sequential domains, respectively, using molecular simulation. We found that the viscosity behavior depends on the surfactant concentration and the chemical nature of the wall surface. For instance, although the concentration levels of the surfactants are the same (c = 10%), completely different viscosity behaviors were observed in the two sequential domains (Newtonian-like) and the four and eight sequential domains (strong shear-thinning) of the JANTs. Our simulations demonstrated how the rheological properties of aqueous surfactant solutions, including viscosity and velocity profiles, can be controlled by the chemical nature of the JANT wall surface, effect of confinement, and their self-assembly structures. Considering the foregoing, we hope that our study offers new knowledge on nanofluid systems.
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Affiliation(s)
- Hiroaki Tsujinoue
- Department of Mechanical Engineering, Keio University, Yokohama 223-8522, Japan
| | - Yusei Kobayashi
- Department of Mechanical Engineering, Keio University, Yokohama 223-8522, Japan
| | - Noriyoshi Arai
- Department of Mechanical Engineering, Keio University, Yokohama 223-8522, Japan
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Feng YH, Zhang XP, Zhao ZQ, Guo XD. Dissipative Particle Dynamics Aided Design of Drug Delivery Systems: A Review. Mol Pharm 2020; 17:1778-1799. [DOI: 10.1021/acs.molpharmaceut.0c00175] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Yun Hao Feng
- Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P.R. China
- Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology), Ministry of Education, Beijing 100029, China
| | - Xiao Peng Zhang
- Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P.R. China
- Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology), Ministry of Education, Beijing 100029, China
| | - Ze Qiang Zhao
- Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P.R. China
- Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology), Ministry of Education, Beijing 100029, China
| | - Xin Dong Guo
- Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P.R. China
- Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology), Ministry of Education, Beijing 100029, China
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Paiva FL, Hore MJA, Secchi A, Calado V, Maia J, Khani S. Dynamic Interfacial Trapping of Janus Nanorod Aggregates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4184-4193. [PMID: 32200633 DOI: 10.1021/acs.langmuir.9b03604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Taking advantage of both shape and chemical anisotropy on the same nanoparticle offers rich self-assembly possibilities for nanotechnology. Through dissipative particle dynamics calculations, in the present work, the directed assembly of Janus nanorod aggregates and their capability to assemble into metastable novel structures at an interfacial level have been assessed. Symmetric Janus rods become kinetically trapped and exhibit either parallel or antiparallel alignment with respect to their long axis (different compositions). This depends on several factors that have been mapped herein and that can be precisely tuned: Flory-Huggins interaction parameter χ between polymer phases; concentration; shear rate; and even aggregate shape. Ultimately, two different aggregate structures result from rod tumbling that are not observed under quiescent conditions: monolayer-like aggregates exhibiting trapped rods with antiparallel configuration; and stacked nanorod arrays similar to superlattice sheets. These different structures can be controlled by the likelihood with which tumbling Janus rods encounter other aggregate portions showing parallel alignment. Hence, the present study offers fundamental insight into relevant parameters that govern the directed assembly of Janus nanoparticles at an interfacial level. Novel applications may potentially derive from the resulting aggregate structures, such as peculiar displays and sensors.
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Affiliation(s)
- Felipe L Paiva
- Department of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland, Ohio 44106, United States
- School of Chemistry, Universidade Federal do Rio de Janeiro, Rua Horácio Macedo 2030, Cidade Universitária, Rio de Janeiro, Rio de Janeiro 21941-909, Brazil
| | - Michael J A Hore
- Department of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Argimiro Secchi
- Chemical Engineering Graduate Program (COPPE), Universidade Federal do Rio de Janeiro, Rua Horácio Macedo 2030, Cidade Universitária, Rio de Janeiro, Rio de Janeiro 21941-909, Brazil
| | - Verônica Calado
- School of Chemistry, Universidade Federal do Rio de Janeiro, Rua Horácio Macedo 2030, Cidade Universitária, Rio de Janeiro, Rio de Janeiro 21941-909, Brazil
| | - João Maia
- Department of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Shaghayegh Khani
- Department of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland, Ohio 44106, United States
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Kobayashi Y, Nomura K, Kaneko T, Arai N. Replica exchange dissipative particle dynamics method on threadlike micellar aqueous solutions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:115901. [PMID: 31726436 DOI: 10.1088/1361-648x/ab579c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The self-assembly of surfactant molecules can spontaneously result in a variety of micelle morphologies, such as spherical micelles, threadlike micelles, and vesicles, and it is therefore crucial to predict and control the self-assembly to achieve a helpful process in the fields of materials chemistry and engineering. A dissipative particle dynamics (DPD) method used in a coarse-grained molecular simulation is applied to simulate various self-assembling soft matter systems because it can handle greater length and time scales than a typical molecular dynamics simulation (MD). It should be noted that the thorough sampling of a system is not assured at low temperatures because of large complex systems with coarse-grained representations. In this article, we demonstrate that the replica exchange method (REM) is very effective for even a DPD in which the energy barrier is comparatively lower than that of a MD. A replica exchange on DPD (REDPD) simulation for threadlike micellar aqueous solutions was conducted, and the values of the potential energy and the mean aggregation number were compared. As a result, the correct values and a self-assembled structure within a low-temperature range can only be obtained through the REDPD.
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Affiliation(s)
- Yusei Kobayashi
- Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
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Miwatani R, Takahashi KZ, Arai N. Performance of Coarse Graining in Estimating Polymer Properties: Comparison with the Atomistic Model. Polymers (Basel) 2020; 12:polym12020382. [PMID: 32046337 PMCID: PMC7077424 DOI: 10.3390/polym12020382] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/20/2020] [Accepted: 01/26/2020] [Indexed: 01/23/2023] Open
Abstract
Combining atomistic and coarse-grained (CG) models is a promising approach for quantitative prediction of polymer properties. However, the gaps between the length and time scales of atomistic and CG models still need to be bridged. Here, the scale gaps of the atomistic model of polyethylene melts, the bead–spring Kremer–Grest model, and dissipative particle dynamics with the slip-spring model were investigated. A single set of spatial and temporal scaling factors was determined between the atomistic model and each CG model. The results of the CG models were rescaled using the set of scaling factors and compared with those of the atomistic model. For each polymer property, a threshold value indicating the onset of static or dynamic universality of polymers was obtained. The scaling factors also revealed the computational efficiency of each CG model with respect to the atomistic model. The performance of the CG models of polymers was systematically evaluated in terms of both the accuracy and computational efficiency.
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Affiliation(s)
- Ryota Miwatani
- Department of Mechanical Engineering, Kindai University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8522, Japan;
| | - Kazuaki Z. Takahashi
- Research Center for Computational Design of Advanced Functional Materials, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Correspondence: ; Tel.: +81-29-861-2972; Fax: +81-29-861-5375
| | - Noriyoshi Arai
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522, Japan;
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10
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Firdous T, Potter DK. Assembling Magnetic Nanoparticles on Nanomechanical Resonators for Torque Magnetometry. Int J Mol Sci 2020; 21:ijms21030984. [PMID: 32024227 PMCID: PMC7037736 DOI: 10.3390/ijms21030984] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/19/2020] [Accepted: 01/22/2020] [Indexed: 01/09/2023] Open
Abstract
We report a highly compliant process for patterning nanoparticle arrays on micro- and nanomechanical devices. The distinctive step involves the single layer self-assembled nanoparticles on top of released nanomechanical devices. We demonstrate the process by fabricating sizable arrays of nanomechanical devices on silicon-on-insulator substrates, acting as nanomechanical torque magnetometers. Later, the nanoparticles were self-assembled in geometrical shapes on top of the devices by a unique combination of top-down and bottom-up methods. The self-assembled array of nanoparticles successfully showed a magnetic torque signal by magnetic actuation of the magnetometer. This patterning process can be generalized for any shape and for a wide range of nanoparticles on the nanomechanical resonators.
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Affiliation(s)
- Tayyaba Firdous
- Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada;
- National Research Council of Canada, 11421 Saskatchewan Dr NW, Edmonton, AB T6G 2M9, Canada
| | - David K. Potter
- Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada;
- Correspondence:
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Kobayashi Y, Arai N, Nikoubashman A. Structure and dynamics of amphiphilic Janus spheres and spherocylinders under shear. SOFT MATTER 2020; 16:476-486. [PMID: 31803898 DOI: 10.1039/c9sm01937e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We study the structure formation and flow properties of colloidal dispersions comprised of Janus spheres, Janus spherocylinders, and their mixtures, using hybrid molecular dynamics simulations that take into account hydrodynamic interactions. We systematically vary the Janus balance and the shape anisotropy of the particles, and explore a range of colloid volume fractions in the liquid regime of the phase diagram. At rest, Janus spheres with small hydrophobic patches form spherical micelles for all investigated colloid concentrations. In contrast, Janus spheres with an entirely hydrophobic hemisphere aggregate to larger worm-like micelles and network-like structures. Janus spherocylinders exhibit a similar self-assembly behavior. At small and intermediate shear, we observe deformation and rearrangement of the micelles, accompanied by a Newtonian-like rheology with slightly higher shear viscosity compared to homoparticle dispersions at the same concentration. As the shear rate is increased further, the micelles eventually break up into small dimers and free particles, causing a distinct shear-thinning of the dispersions. The network-like structures exhibit a similar flow behavior at high shear rates, but for weak shear we find an almost threefold increase of the shear viscosity and a distinct shear-thinning behavior due to the fracturing of the intertwined networks. In general, we identify a strong correlation between the size of the aggregates and the rheology of the dispersions, allowing for the determination of dynamic properties solely based on structural information.
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Affiliation(s)
- Yusei Kobayashi
- Department of Mechanical Engineering, Keio University, Kohoku-ku, Yokohama, Japan.
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12
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Araki Y, Arai N. Dissociation effect of non-covalent bond for morphological behavior of triblock copolymers: a dissipative particle dynamics study. CHEM ENG COMMUN 2019. [DOI: 10.1080/00986445.2019.1680369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Yusuke Araki
- Department of Mechanical Engineering, Keio University, Yokohama, Japan
| | - Noriyoshi Arai
- Department of Mechanical Engineering, Keio University, Yokohama, Japan
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14
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Inokuchi T, Arai N. Relationship between water permeation and flip-flop motion in a bilayer membrane. Phys Chem Chem Phys 2018; 20:28155-28161. [PMID: 30387788 DOI: 10.1039/c8cp04610g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The lipid bilayer membrane facilitates various biological reactions and is thus an essential structure that sustains all higher forms of life. The unique local environment of the lipid bilayer plays critical roles for the diffusion of biomolecules as well as water molecules in biological reactions. Although fluctuation of the cell membrane is expected to allow for the transport of some water molecules, the flip-flop of lipid molecules corresponds to lipid transport between membrane leaflets, and is considered to be an important process to regulate the lipid composition of biological membranes. However, the relationship between these flip-flop phenomena and surrounding water molecules remains poorly understood. We hypothesized that the flip-flop is caused by water molecules permeating through the cell membrane. To test this hypothesis, we used millisecond-order coarse-grained molecular simulations (dissipative particle dynamics) to investigate the distance between water molecules and lipid molecules depending on the position of the lipid molecule. The results clearly showed that water molecules affect the flip-flop motion in the early stage, but have minimal contribution to the subsequent behavior. Moreover, based on the results of dissipative particle dynamics simulation, we computed several first-passage-time (FPT) quantities to describe the detailed dynamics of water permeation. We modeled arrangements in the middle of the flip-flop process, which were compared with the arrangement without lipid molecules. Overall, our results indicate that lipid molecules located both in perpendicular and parallel arrangements largely affect water permeation. These findings provide new insight into the detailed relationship between water permeation and the flip-flop motion.
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Affiliation(s)
- Takuya Inokuchi
- Department of Mechanical Engineering, Kindai University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan
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Zheng X, Cheng W, Chen S, Chen J, Chen Q. Fabrication of anisotropic janus composite particles based on natural renewable urushiol. POLYM ENG SCI 2018. [DOI: 10.1002/pen.24937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Xuelin Zheng
- College of Chemistry and Materials Science Fujian Normal University Fuzhou 350007 China
- Fujian Key Laboratory of Polymer Materials Fuzhou 350007 China
| | - Wei Cheng
- College of Chemistry and Materials Science Fujian Normal University Fuzhou 350007 China
| | - Shuning Chen
- College of Chemistry and Materials Science Fujian Normal University Fuzhou 350007 China
| | - Jiawen Chen
- College of Chemistry and Materials Science Fujian Normal University Fuzhou 350007 China
| | - Qinhui Chen
- College of Chemistry and Materials Science Fujian Normal University Fuzhou 350007 China
- Fujian Key Laboratory of Polymer Materials Fuzhou 350007 China
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Wang X, Zhang Z, Torsæter O, He J. Atomistic insights into the nanofluid transport through an ultra-confined capillary. Phys Chem Chem Phys 2018; 20:4831-4839. [PMID: 29383352 DOI: 10.1039/c7cp08140e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nanofluid or nanoparticle (NP) transport in confined channels is of great importance for many biological and industrial processes. In this study, molecular dynamics simulation has been employed to investigate the spontaneous two-phase displacement process in an ultra-confined capillary controlled by the surface wettability of NPs. The results clearly show that the presence of NPs modulates the fluid-fluid meniscus and hinders the displacement process compared with the NP-free case. From the perspective of motion behavior, hydrophilic NPs disperse in the water phase or adsorb on the capillary, while hydrophobic and mixed-wet NPs are mainly distributed in the fluid phase. The NPs dispersed into fluids tend to increase the viscosity of the fluids, while the adsorbed NPs contribute to the wettability alteration of the solid capillary. Via capillary number calculations, it is uncovered that the viscosity increase of fluids is responsible for the hindered spontaneous displacement process by hydrophobic and mixed NPs. The wettability alteration of the capillary induced by adsorbed NPs dominates the enhanced displacement in the case of hydrophilic NPs. Our findings provide guidance for modifying the rate of capillary filling and reveal the microscopic mechanism transporting NPs into porous media, which is significant to the design of NPs for target applications.
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Affiliation(s)
- Xiao Wang
- NTNU Nanomechanical Lab, Department of Structural Engineering, Faculty of Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway.
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DeLaCruz-Araujo RA, Beltran-Villegas DJ, Larson RG, Córdova-Figueroa UM. Shear-Induced Alignment of Janus Particle Lamellar Structures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:1051-1060. [PMID: 29077413 DOI: 10.1021/acs.langmuir.7b02921] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Control over the alignment of colloidal structures plays a crucial role in advanced reconfigurable materials. In this work, we study the alignment of Janus particle lamellar structures under shear flow via Brownian dynamics simulations. Lamellar alignment (orientation relative to flow direction) is measured as a function of the Péclet number (Pe)-the ratio of the viscous shear to the Brownian forces-the particle volume fraction, and the strength of the anisotropic interaction potential made dimensionless with thermal energy. Under conditions where lamellar structures are formed, three orientation regimes are observed: (1) random orientation for very small Pe, (2) parallel orientation-lamellae with their normals parallel to the direction of the velocity gradient-for intermediate values of Pe, and (3) perpendicular orientation-lamellae with their normals parallel to the vorticity direction-for large Pe. To understand the alignment mechanism, we carry out a scaling analysis of competing torques between a pair of particles in the lamellar structure. Our results suggest that the change of parallel to perpendicular orientation is independent of the particle volume fraction and is caused by the hydrodynamic and Brownian torques on the particles overcoming the torques resulting from the interparticle interactions. This initial study of shear-induced alignment on lamellar structures formed by Janus colloidal particles also opens the door for future applications where a reversible actuator for structure orientation is required.
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Affiliation(s)
- Ronal A DeLaCruz-Araujo
- Department of Chemical Engineering, University of Puerto Rico-Mayagüez , Mayagüez, Puerto Rico 00681, United States
| | - Daniel J Beltran-Villegas
- Department of Chemical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Ronald G Larson
- Department of Chemical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Ubaldo M Córdova-Figueroa
- Department of Chemical Engineering, University of Puerto Rico-Mayagüez , Mayagüez, Puerto Rico 00681, United States
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Taniguchi Y, Sazali MAB, Kobayashi Y, Arai N, Kawai T, Nakashima T. Programmed Self-Assembly of Branched Nanocrystals with an Amphiphilic Surface Pattern. ACS NANO 2017; 11:9312-9320. [PMID: 28872823 DOI: 10.1021/acsnano.7b04719] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Site-selective surface modification on the shape-controlled nanocrystals is a key approach in the programmed self-assembly of inorganic colloidal materials. This study demonstrates a simple methodology to gain self-assemblies of semiconductor nanocrystals with branched shapes through tip-to-tip attachment. Short-chained water-soluble cationic thiols are employed as a surface ligand for CdSe tetrapods and CdSe/CdS core/shell octapods. Because of the less affinity of arm-tip to the surface ligands compared to the arm-side wall, the tip-surface becomes uncapped to give a hydrophobic nature, affording an amphiphilic surface pattern. The amphiphilic tetrapods aggregated into porous agglomerates through tip-to-tip connection in water, while they afforded a hexagonally arranged Kagome-like two-dimensional (2D) assembly by the simple casting of aqueous dispersion with the aid of a convective self-assembly mechanism. A 2D net-like assembly was similarly obtained from amphiphilic octapods. A dissipative particle dynamics simulation using a planar tripod model with an amphiphilic surface pattern reproduced the formation of the Kagome-like assembly in a 2D confined space, demonstrating that the lateral diffusion of nanoparticles and the firm contacts between the hydrophobic tips play crucial roles in the self-assembly.
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Affiliation(s)
- Yuki Taniguchi
- Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST) , Ikoma, Nara 630-0192, Japan
| | | | - Yusei Kobayashi
- Department of Mechanical Engineering, Kindai Unversity , Higashiosaka, Osaka 577-8502, Japan
| | - Noriyoshi Arai
- Department of Mechanical Engineering, Kindai Unversity , Higashiosaka, Osaka 577-8502, Japan
| | - Tsuyoshi Kawai
- Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST) , Ikoma, Nara 630-0192, Japan
| | - Takuya Nakashima
- Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST) , Ikoma, Nara 630-0192, Japan
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Bordin JR, Krott LB. How Competitive Interactions Affect the Self-Assembly of Confined Janus Dumbbells. J Phys Chem B 2017; 121:4308-4317. [DOI: 10.1021/acs.jpcb.7b01696] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- José Rafael Bordin
- Campus Caçapava
do Sul, Universidade Federal do Pampa, Av. Pedro Anunciação,
111, CEP 96570-000, Caçapava do Sul, RS, Brazil
| | - Leandro B. Krott
- Centro Araranguá, Universidade Federal de Santa Catarina, Rua Pedro João Pereira, 150, CEP 88905-120, Araranguá, SC, Brazil
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