Characterization of the dynamics of interfaces and of interface-dominated systems via spectroscopy and microscopy techniques

Cristofolini, Luigi; Orsi, Davide; Isa, Lucio

doi:10.1016/j.cocis.2018.06.001

Cited by 17 publications

(8 citation statements)

References 136 publications

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“…Although a large number of experimental techniques can be used to study translational diffusion, very few can measure precisely the interfacial diffusion with a high spatial/temporal resolution. Here we chose fluorescence correlation spectroscopy (FCS) that is very well suited for such a task. − This is because the concept of FCS is based on monitoring the fluorescence fluctuations originating from fluorescent species diffusing in and out of a very small (<1 μm 3 ) confocal volume (Figure b). In a representative experiment, the confocal volume was first scanned across the water/alkane interface with adsorbed nanoparticles to find its precise location at the position of the maximum detected fluorescence (Figure c).…”

Section: Resultsmentioning

confidence: 99%

Brownian Diffusion of Individual Janus Nanoparticles at Water/Oil Interfaces

et al. 2020

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Janus nanoparticles could exhibit a higher interfacial activity and adsorb stronger to fluid interfaces than homogeneous nanoparticles of similar sizes. However, little is known about the interfacial diffusion of Janus nanoparticles and how it compares to that of homogeneous ones. Here, we employed fluorescence correlation spectroscopy to study the lateral diffusion of ligand-grafted Janus nanoparticles adsorbed at water/oil interfaces. We found that the diffusion was significantly slower than that of homogeneous nanoparticles. We carried out dissipative particle dynamic simulations to study the mechanism of interfacial slowdown. Good agreement between experimental and simulation results has been obtained only provided that the flexibility of ligands grafted on the nanoparticle surface was taken into account. The polymeric ligands were deformed and oriented at an interface so that the effective radius of Janus nanoparticles is larger than the nominal one obtained by measuring the diffusion in bulk solution. These findings highlight further the critical importance of the ligands grafted on Janus nanoparticles for applications involving nanoparticle adsorption at an interface, such as oil recovery or two-dimensional self-assembly.

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Section: Resultsmentioning

confidence: 99%

Brownian Diffusion of Individual Janus Nanoparticles at Water/Oil Interfaces

et al. 2020

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“…The hydrodynamics interactions can appear coupled to some additional processes associated with the initial velocity of the colloids, resulting from a time-dependent velocity field due to the particle motion. This type of motion presents a characteristic time associated with the transverse diffusion coefficient [30,106,107].…”

Section: Dynamics Of Colloids Trapped At Fluid Interfacesmentioning

confidence: 99%

“…Thus, it is possible to assume that the motion of a colloid can be described as a diffusion process affected for the interactions with neighboring colloids. Information about the dynamics of trapped particles can be obtained by analyzing the trajectories of colloids at the interface, which gives information on the mean square displacement (MSD, ∆r 2 (t) ), which is related to the diffusion coefficient, D, and the characteristic length of the translational motion [30,89,90,107,108],…”

Section: Dynamics Of Colloids Trapped At Fluid Interfacesmentioning

confidence: 99%

“…where α is a scale exponent and d represent the number of dimensions. Considering a low interfacial coverage, linear dependence of the MSD would be expected on time, with the diffusion coefficient obtained from the slope of the representation defined by Equation (9) [30,107]. The increase of the coverage leads the system to a more complex dynamic, with the following two clear thresholds: (i) short times and (ii) long times.…”

Section: Dynamics Of Colloids Trapped At Fluid Interfacesmentioning

confidence: 99%

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Colloids at Fluid Interfaces

Maestro

Guzmán

2019

Processes

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Over the last two decades, understanding of the attachment of colloids to fluid interfaces has attracted the interest of researchers from different fields. This is explained by considering the ubiquity of colloidal and interfacial systems in nature and technology. However, to date, the control and tuning of the assembly of colloids at fluid interfaces remain a challenge. This review discusses some of the most fundamental aspects governing the organization of colloidal objects at fluid interfaces, paying special attention to spherical particles. This requires a description of different physicochemical aspects, from the driving force involved in the assembly to its thermodynamic description, and from the interactions involved in the assembly to the dynamics and rheological behavior of particle-laden interfaces.

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“…Only few experimental studies have quantified the location of microgels at liquid-liquid interfaces by introducing the concept of two contact angles on lens-like shape particles. 24,25 This however rises the question if due to the solvent penetrability the definition of any contact angle has any sense in such systems. 11,14 Anyhow, it is evident that alternative approaches are required to understand particle conformations at interfaces.…”

Section: Introductionmentioning

confidence: 99%

Deformability and solvent penetration in soft nanoparticles at liquid-liquid interfaces

Arismendi‐Arrieta

Moreno

2020

Journal of Colloid and Interface Science

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Soft nanoparticles hold promise as smart emulsifiers due to their high degree of deformability, permeability and stimuli responsive properties. By means of large-scale simulations we investigate the structural properties of nanogels at liquid-liquid (A-B) interfaces and the miscibility of the liquids inside the nanogels, covering the whole range of interfacial strength from the limit of single-liquid to the case of stiff interfaces. To study the role of the internal architecture and deformability of the nanogel we simulate a realistic disordered and an ideal regular network, for a broad range of cross-linking degrees. Unlike in previous investigations on liquid miscibility, excluded volume interactions are considered for both the monomers and the explicit solvent particles. The nanogel permeability is analysed by using an unbiased grid representation that accounts for the surface fluctuations and adds to the density profiles the exact number of liquid particles inside the nanogel. The better packing efficiency of the regular network leads 1 arXiv:1911.06725v1 [cond-mat.soft] 15 Nov 2019to higher values of the total liquid uptake and the invasive capacity (A-particles in B-side and viceversa) than in the disordered network, though differences vanish in the limit of rigid interfaces. Uptake and invasion are optimized at a cross-linking degree that depends on the interfacial strength, tending to ∼ 15 − 20 for moderate and stiff interfaces. As the interfacial strength increases, the miscibility inside the nanogel is enhanced by a factor of up to 5 with respect to the bare interface, with the disordered networks providing a better mixing than their ideal counterparts. The emerging scenario reported here provides general guidelines for tuning the shape, uptake, invasive, and mixing capacities of nanogels adsorbed at liquid-liquid interfaces.

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Characterization of the dynamics of interfaces and of interface-dominated systems via spectroscopy and microscopy techniques

Cited by 17 publications

References 136 publications

Brownian Diffusion of Individual Janus Nanoparticles at Water/Oil Interfaces

Brownian Diffusion of Individual Janus Nanoparticles at Water/Oil Interfaces

Colloids at Fluid Interfaces

Deformability and solvent penetration in soft nanoparticles at liquid-liquid interfaces

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