Dynamics in Ultrathin Films: Particle Tracking Microrheology of Langmuir Monolayers

Bonales, Laura J.; Ritacco, Hernán; Rubio, J. E.; Rubio, Ramón G.; Monroy, Francisco; Ortega, Francisco

doi:10.2174/1874067700701010025

Cited by 17 publications

(7 citation statements)

References 37 publications

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“…Bonales et al have calculated the shear viscosity of two polymer Langmuir films using Danov's theory, and compared these values with those obtained by canal viscosimetry [68]. Video particle tracking together with Danov's theory were used by Hilles et al [69] to study the glass transition in Langmuir films.…”

Section: Particle Tracking Resultsmentioning

confidence: 99%

Interfacial microrheology: Particle tracking and related techniques

Ortega

Ritacco

Rubio

2010

Current Opinion in Colloid & Interface Science

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108

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Section: Particle Tracking Resultsmentioning

confidence: 99%

Interfacial microrheology: Particle tracking and related techniques

Ortega

Ritacco

Rubio

2010

Current Opinion in Colloid & Interface Science

Self Cite

108

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“…They are also claimed to mimic a broad range of collective phenomena, ranging from self-assembly of virus capsids and self-organization of magnetic flux vortices in superconductors to Jeans’s gravitational instability in astrophysics. , The remarkable recent progress in the fields above was achieved in studies addressing ordered ,− and disordered, ,,,, micrometer-sized CPs residing at structureless and disordered liquid interfaces only. However, many liquid interfaces exhibit some degree of ordering on a molecular scale. − In some cases, a disordered liquid bulk coexists, over an extended temperature range, with a crystalline surface monolayer of the same molecules or a mixed surfactant-alkane Langmuir–Gibbs monolayer. − CPs embedded in such a planar surface monolayer are essentially immobilized . However, if the crystalline monolayer resides at the surface of a droplet, the spherical topology , necessarily dictates the presence of a large number of structural defects within the monolayer, which should allow a higher mobility for a single CP or a few CPs residing at the surface.…”

Section: Introductionmentioning

confidence: 99%

Precise Self-Positioning of Colloidal Particles on Liquid Emulsion Droplets

et al. 2019

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Decorating emulsion droplets by particles stabilizes foodstuff and pharmaceuticals. Interfacial particles also influence aerosol formation, thus impacting atmospheric CO 2 exchange. While studies of particles at disordered droplet interfaces abound in the literature, such studies for ubiquitous ordered interfaces are not available. Here we report such an experimental study, showing that particles residing at crystalline interfaces of liquid droplets spontaneously self-position to specific surface locations, identified as structural topological defects in the crystalline surface monolayer. This monolayer forms at temperature T = T s , leaving the droplet liquid, and driving at T d < T s a spontaneous shape-change transition of the droplet from spherical to icosahedral. The particle's surface position remains unchanged in the transition demonstrating these positions to coincide with the vertices of the sphere-inscribed icosahedron. On further cooling, droplet shape-changes to other polyhedra occur, with the particles remaining invariably at the polyhedra's vertices. At still lower temperatures the particles are spontaneously expelled from the droplets. Our results probe the molecular-scale elasticity of quasi-two-dimensional curved crystals, impacting also other fields, such as protein positioning on cell membranes, controlling essential biological functions. Using ligand-decorated particles, and the precise temperature-tunable surface position control found here, may also allow using these droplets for directed supra-droplets self-assembly into larger structures, with a possible post-assembly structure-fixation by UV-polymerization of the droplet's liquid.

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“…20(b)], given that the numerical methods differ and that we are operating in a differently bounded domain. Bonales et al 61 have used Danov's theory to calculate the shear viscosity of two polymer Langmuir films. They compared the results with the data obtained by canal viscosimetry.…”

Section: Table IImentioning

confidence: 99%

Drag on a spherical particle at the air–liquid interface: Interplay between compressibility, Marangoni flow, and surface viscosities

et al. 2021

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We investigate the flow of viscous interfaces carrying an insoluble surface active material, using numerical methods to shed light on the complex interplay between Marangoni stresses, compressibility, and surface shear and dilatational viscosities. We find quantitative relations between the drag on a particle and interfacial properties as they are required in microrheology, i.e., going beyond the asymptotic limits. To this end, we move a spherical particle probe at constant tangential velocity, symmetrically immersed at either the incompressible or compressible interface, in the presence and absence of surfactants, for a wide range of system parameters. A full three-dimensional finite element calculation is used to reveal the intimate coupling between the bulk and interfacial flows and the subtle effects of the different physical effects on the mixed-type velocity field that affects the drag coefficient, both in the bulk and at the interface. For an inviscid interface, the directed motion of the particle leads to a gradient in the concentration of the surface active species, which in turn drives a Marangoni flow in the opposite direction, giving rise to a force exerted on the particle. We show that the drag coefficient at incompressible interfaces is independent of the origin of the incompressibility (dilatational viscosity, Marangoni effects or a combination of both) and that its higher value can not only be related to the Marangoni effects, as suggested earlier. In confined flows, we show how the interface shear viscosity suppresses the vortex at the interface, generates a uniform flow, and consequently increases the interface compressibility and the Marangoni force on the particle. We mention available experimental data and provide analytical approximations for the drag coefficient that can be used to extract surface viscosities.

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Dynamics in Ultrathin Films: Particle Tracking Microrheology of Langmuir Monolayers

Cited by 17 publications

References 37 publications

Interfacial microrheology: Particle tracking and related techniques

Interfacial microrheology: Particle tracking and related techniques

Precise Self-Positioning of Colloidal Particles on Liquid Emulsion Droplets

Drag on a spherical particle at the air–liquid interface: Interplay between compressibility, Marangoni flow, and surface viscosities

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