Polymodal rheological behaviors induced by self-assembly of surfactants confined in nanotubes

Kobayashi, Yusei; Arai, Noriyoshi

doi:10.1016/j.molliq.2018.10.141

Cited by 10 publications

(24 citation statements)

References 29 publications

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“…At rest, spherical and threadlike micelles were observed at

and

, respectively. These equilibrium morphologies were consistent with those in previous simulation results [ 50 ] obtained using a tube model with a 60% smaller radius than the one in this study. Snapshots of these morphologies are shown in Figure S1 of the Supplemental Materials .…”

Section: Resultssupporting

confidence: 93%

“…The inner surface of the cylindrical tube was treated as smooth, in agreement with our previous studies [ 43 , 48 , 50 , 51 ]. The potential function of the smooth wall was built by summing the DPD force between every solution particle and the wall particles [ 54 ].…”

Section: Model and Methodssupporting

confidence: 56%

“…Figure 2 shows the frictional coefficient

of the pipe as a function of

. The volumetric flow rate, Q , is estimated by applying the cylindrical shell method to a velocity profile [ 50 , 51 , 58 ] and a generalized Reynolds number is used [ 59 , 60 ], as we focus on the onset point of the transition to turbulence. Here, the power-law parameter, n , is obtained from the relation between the wall shear rate,

, and the wall shear stress,

, in the steady state (see Figure S2 in the Supplementary Materials ).…”

Section: Resultsmentioning

confidence: 99%

“…As the repulsive parameters increase between hydrophilic head groups, the hydration radius may also be estimated to be larger. The same values of interaction parameters were adopted in many studies [ 43 , 47 , 48 , 49 , 50 , 51 ]. We also examined that our previous bulk simulation of CTAB containing a NaSal solution [ 47 ] produced the same results as those in a previous examination that Yamamoto and Hyodo performed [ 46 ].…”

Section: Model and Methodsmentioning

confidence: 99%

“…The noise amplitude and friction coefficient were set to be 3.0 and 4.5, respectively. The temperature was set at a constant value, i.e., 1.0 k B T. The inner surface of the cylindrical tube was treated as smooth, in agreement with our previous studies [43,48,50,51]. The potential function of the smooth wall was built by summing the DPD force between every solution particle and the wall particles [54].…”

Section: Simulation Model and Conditionsmentioning

confidence: 99%

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Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

Kobayashi

Gomyo

Arai

2021

IJMS

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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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“…At rest, spherical and threadlike micelles were observed at

and

Section: Resultssupporting

confidence: 93%

Section: Model and Methodssupporting

confidence: 56%

“…Figure 2 shows the frictional coefficient

of the pipe as a function of

, and the wall shear stress,

, in the steady state (see Figure S2 in the Supplementary Materials ).…”

Section: Resultsmentioning

confidence: 99%

Section: Model and Methodsmentioning

confidence: 99%

Section: Simulation Model and Conditionsmentioning

confidence: 99%

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Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

Kobayashi

Gomyo

Arai

2021

IJMS

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Formation of ultrathin scarf-like micelles, ultrathin disk-like micelles and spherical micelles by self-assembly of polyurethane diblock copolymers

Liu

et al. 2022

Journal of Molecular Liquids

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Effect of the Janus Amphiphilic Wall on the Viscosity Behavior of Aqueous Surfactant Solutions

2020

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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 selfassembled 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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Polymodal rheological behaviors induced by self-assembly of surfactants confined in nanotubes

Cited by 10 publications

References 29 publications

Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

Formation of ultrathin scarf-like micelles, ultrathin disk-like micelles and spherical micelles by self-assembly of polyurethane diblock copolymers

Effect of the Janus Amphiphilic Wall on the Viscosity Behavior of Aqueous Surfactant Solutions

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