Dynamics in Ultrathin Films: Particle Tracking Microrheology of Langmuir Monolayers

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

doi:10.2174/187406770701012507

Cited by 8 publications

(15 citation statements)

References 27 publications

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“…As we have shown in a previous work, 45 this condition is fulfilled in our case. One important point that should be stressed here is that the contact angle depends on the solvent used to spread the particles, 45 and the contact angle is a key variable for the hydrodynamic calculations used to estimate the surface shear viscosity from the diffusion coefficient, 43,44,50,51 therefore one has to be very careful when comparing results obtained using different spreading solvents for a given probe particle.…”

Section: Contact Anglesmentioning

confidence: 99%

Surface rheology: macro- and microrheology of poly(tert-butyl acrylate) monolayers

et al. 2011

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We have studied the surface shear viscoelasticity of poly(tert-butyl-acrylate) Langmuir monolayers spread at the air/water interface, by tracking the Brownian motion of tracer particles with different sizes and surface chemical nature, trapped at the same interface. Surface shear moduli have been extracted from the particles mean square displacements (MSD), using different approaches: hydrodynamic calculations of drag coefficients and direct inversion of the MSD by means of the generalized Stokes-Einstein equation. It has been found that these different theoretical approaches lead to comparable values of the shear interfacial viscosity independent of the polymer concentration and molecular weight. In addition, no effect of the size or chemical nature of the probe has been detected. The results have demonstrated the consistency of the microrheological techniques used, and confirm the existence of entanglements in PtBA monolayers, as recently deduced from dilational elasticity and viscosity measurements, [Maestro et al., Soft Matter, 2010, 6, 4407]. An unexpected result was that the interfacial viscosity values obtained from microrheology have been found to be several orders of magnitude lower than the ones obtained with macroscopic interfacial shear rheometers. At the moment there is no clear explanation for this disagreement, although it is not related to the probe size or their chemical nature. Furthermore, this discrepancy is not related to the analysis methodology used, including the calculation of the two-point correlation function used in 3D microrheology when there are heterogeneities present within the range of the probe size.

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Section: Contact Anglesmentioning

confidence: 99%

Surface rheology: macro- and microrheology of poly(tert-butyl acrylate) monolayers

et al. 2011

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“…[16][17][18] CPs embedded in such a planar surface monolayer are essentially immobilized. 19 However, if the crystalline monolayer resides at the surface of a droplet, the spherical topology 5,9 necessarily dictates the presence of a large number of structural defects within the monolayer 20 , which should allow a higher mobility, for a single or a few CPs residing at the surface. Thus, fundamentally new dynamics are expected [21][22][23][24] to take place for CPs bound at such curved crystalline…”

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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“…Figure 8 shows the results obtained for a monolayer of poly(4-hydroxystyrene) onto water. For all the monolayers reported by Bonales et al (2007) and Maestro et al (2011.b) the surface shear viscosity calculated from Danov's theory was lower than that measured with the macroscopic canal surface viscometer. Similar qualitative conclusions were reached at by Sickert et al (2007) for monolayers of fatty acids and phospholipids in the liquid expanded region.…”

Section: Danov's Model For a Sphere In A Compressible Surfactant Layermentioning

confidence: 63%

“…In the case of Langmuir films of polymers, the monolayer could be considered as compressible or incompressible depending on the rate of the polymer dynamics at the interface compared to the velocity of the beads probes. Bonales et al (2007) have calculated the shear viscosity of two polymer Langmuir films using Danov's theory, and compared these values with those obtained by canal viscosimetry. Video Particle tracking and Danov's theory were used by Maestro et al (2011.a) to show the glass transition in Langmuir films.…”

Section: Danov's Model For a Sphere In A Compressible Surfactant Layermentioning

confidence: 99%

Microrheology of Complex Fluids

Bonales¹,

Maestro²,

Rubio³

et al. 2011

Hydrodynamics - Advanced Topics

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Dynamics in Ultrathin Films: Particle Tracking Microrheology of Langmuir Monolayers

Cited by 8 publications

References 27 publications

Surface rheology: macro- and microrheology of poly(tert-butyl acrylate) monolayers

Surface rheology: macro- and microrheology of poly(tert-butyl acrylate) monolayers

Precise Self-Positioning of Colloidal Particles on Liquid Emulsion Droplets

Microrheology of Complex Fluids

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