<i>Interfacial Transport Processes and Rheology</i>

Edwards, David A.; Brenner, Howard; Wasan, Darsh T.; Kraynik, Andrew M.

doi:10.1063/1.2808875

Cited by 152 publications

(260 citation statements)

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“…Here, the basic equations in the steady-state for describing the monolayer are given by the 2D equivalent Stokes equation 29,30 and by the mass conservation equation where In these equations∇ ⊥ is the operator that applies only to the in-plane coordinates, γ is the surface tension, η s and η are the monolayer and the subphase viscosities, respectively. To compare the relative importance of surface and the viscous terms in eq 4 is critical, and it is necessary to note that the ratio of the surface to the subphase bulk viscous terms is of the order q ; 29 ) η s /η and q ) 2π/l, where l is a relevant periodicity size of LC domains in a supersaturated LE phase following a mechanical compression.…”

Section: Models To Explain Pattern Formation In Langmuir Monolayersmentioning

confidence: 99%

Domain Growth, Pattern Formation, and Morphology Transitions in Langmuir Monolayers. A New Growth Instability

2010

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The aims of this study are the following two: (1) To show that in Langmuir monolayers (LM) at low supersaturation, domains grow forming fractal structures without an apparent orientational order trough tip splitting dynamics, where doublons are the building blocks producing domains with a seaweed shape. When supersaturation is larger, there is a morphology transition from tip splitting to side branching. Here, structures grow with a pronounced orientational order forming dendrites, which are also fractal. We observed this behavior in different Langmuir monolayers formed by nervonic acid, dioctadecylamine, ethyl stearate, and ethyl palmitate, using Brewster angle microscopy. (2) To present experimental evidence showing an important Marangoni flow during domain growth, where the hydrodynamic transport of amphipiles overwhelms diffusion. We were able to show that the equation that governs the pattern formation in LM is a Laplacian equation in the chemical potential with the appropriate boundary conditions. However, the underlying physics involved in Langmuir monolayers is different from the underlying physics in the Mullins-Sekerka instability; diffusional processes are not involved. We found a new kind of instability that leads to pattern formation, where Marangoni flow is the key factor. We also found that the equations governing pattern formation in LM can be reduced to those used in the theory of morphology diagrams for two-dimensional diffusional growth. Our experiments agree with this diagram.

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Section: Models To Explain Pattern Formation In Langmuir Monolayersmentioning

confidence: 99%

Domain Growth, Pattern Formation, and Morphology Transitions in Langmuir Monolayers. A New Growth Instability

2010

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“…The azimuthal vorticity η on the solid boundaries is determined by evaluating Eq. [3] on the boundaries once ψ is known. On the air-water interface, being a material surface, ψ is continuous with its value on the side walls, which we set to zero without loss of generality.…”

Section: Governing Equationsmentioning

confidence: 99%

“…At this stage, we need to solve the elliptic equation [3] for ψ * with the interior points for η * just computed. Then, the surfactant concentration is advected by this streamfunction.…”

Section: Numerical Techniquementioning

confidence: 99%

Surfactant-Influenced Gas–Liquid Interfaces: Nonlinear Equation of State and Finite Surface Viscosities

Lopez

Hirsa

2000

Journal of Colloid and Interface Science

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“…In addition, it is known that a surfactant monolayer has certain properties characteristic of a hypothetical "two-dimensional liquid." One important property in this class is surface shear viscosity (41).…”

Section: Summary and Future Modeling Workmentioning

confidence: 99%