Structure of colloidal gels at intermediate concentrations: the role of competing interactions

Capellmann, R. F.; Valadez-Pérez, Néstor E.; Simon, Benedikt; Egelhaaf, Stefan U.; Laurati, Marco; Castañeda-Priego, Ramón

doi:10.1039/c6sm01822j

Cited by 20 publications

(14 citation statements)

References 64 publications

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“…At low polymer concentrations, c p /c * p 0.10, all colloidal systems are in the fluid state. When c p /c * p 0.15, the system starts reaching one of the following states: fluid-crystal coexistence, gas-liquid separation and gelation; this is a common behavior for different systems with short-ranged attractions, even at higher colloidal concentrations [33], and coincides with the reported with simulations (Fig. 1a).…”

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confidence: 88%

Reversible Aggregation and Colloidal Cluster Morphology: The Importance of the Extended Law of Corresponding States

2018

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Cluster morphology of spherical particles interacting with a short-range attraction has been extensively studied due to its relevance to many applications, such as the large-scale structure in amorphous materials, phase separation, protein aggregation, and organelle formation in cells. Although it was widely accepted that the range of the attraction solely controls the fractal dimension of clusters, recent experimental results challenged this concept by also showing the importance of the strength of attraction. Using Monte Carlo simulations, we conclusively demonstrate that it is possible to reduce the dependence of the cluster morphology to a single variable, namely, the reduced second virial coefficient, B_{2}^{*}, linking the local properties of colloidal systems to the extended law of corresponding states. Furthermore, the cluster size distribution exhibits two well-defined regimes: one identified for small clusters, whose fractal dimension, d_{f}, does not depend on the details of the attraction, i.e., small clusters have the same d_{f}, and another related to large clusters, whose morphology depends exclusively on B_{2}^{*}, i.e., d_{f} of large aggregates follows a master curve, which is only a function of B_{2}^{*}. This physical scenario is confirmed with the reanalysis of experimental results on colloidal-polymer mixtures.

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confidence: 88%

Reversible Aggregation and Colloidal Cluster Morphology: The Importance of the Extended Law of Corresponding States

2018

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“…Suspensions in the intermediate volume fraction regime (0.1 φ 0.5) are relevant to understanding the role of spinodal decomposition and arrested phase separation in gel formation and are an area of active investigation [3,[5][6][7][8][9][10][11][12][13]. For example, the percolated particle network in the final gel state at intermediate concentrations has been measured, directly or indirectly, via experimental methods such as confocal microscopy [14][15][16][17], ultra-small-angle x-ray-scattering [18] and rheology [11,[19][20][21] and also simulated using molecular dynamics (MD) [22][23][24][25]. Far less studied are the formation and dissolution processes in gels; thermo-reversible colloidal gels are ideal for such investigations because particle interactions can be finely and abruptly tuned via sudden temperature changes.…”

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confidence: 99%

Dynamic Scaling of Colloidal Gel Formation at Intermediate Concentrations

et al. 2017

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We have examined the formation and dissolution of gels composed of intermediate volume-fraction nanoparticles with temperature-dependent short-range attractions using small-angle x-ray scattering, x-ray photon correlation spectroscopy, and rheology to obtain nanoscale and macroscale sensitivity to structure and dynamics. Gel formation after temperature quenches to the vicinity of the rheologically determined gel temperature, T_{gel}, was characterized via the slowdown of dynamics and changes in microstructure observed in the intensity autocorrelation functions and structure factor, respectively, as a function of quench depth (ΔT=T_{quench}-T_{gel}), wave vector, and formation time t_{f}. We find the wave-vector-dependent dynamics, microstructure, and rheology at a particular ΔT and t_{f} map to those at other ΔTs and t_{f}s via an effective scaling temperature, T_{s}. A single T_{s} applies to a broad range of ΔT and t_{f} but does depend on the particle size. The rate of formation implied by the scaling is a far stronger function of ΔT than expected from the attraction strength between colloids. We interpret this strong temperature dependence in terms of cooperative bonding required to form stable gels via energetically favored, local structures.

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“…One of the most important challenges in Colloidal Soft Matter Physics is to understand the mechanisms that give rise to the non-equilibrium states of matter. Although there have been important contributions in the particular case of colloidal gels and glasses [27][28][29][92][93][94][95][96][97][98], it has not yet been possible to understand and establish the relationship between these states of matter [28,99], or even more, it is important to explore the possibility of introducing a universal definition of gel [29] and, in addition, it is necessary to quantify the effects that the gravitational field has on the formation of non-equilibrium states [100]. As mentioned above, it is also interesting to study the effective potentials between macromolecules near the gelation or vitrification boundary.…”

Section: Colloidal Soft Matter Out Of Equilibriummentioning

confidence: 99%

Colloidal Soft Matter Physics

Castañeda-Priego

2021

Rev. Mex. Fís.

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Colloidal soft matter is a class of materials that exhibit rich equilibrium and non-equilibrium 0thermodynamic properties, it self-assembles (spontaneously or driven externally) to form a large diversity of structures, and its constituents display an interesting and complex transport behavior. In this contribution, we review the essential aspects and the modern challenges of Colloidal SoftMatter Physics. Our main goal is to provide a balanced discussion of the various facets of this highly multidisciplinary field, including experiments, theoretical approximations and models for molecular simulations, so that readers with various backgrounds could get both the basics and a broader, more detailed physical picture of the field. To this end, we first put emphasis on the colloidal physics, which allows us to understand the main driving (molecular and thermodynamic) forces between colloids that give rise to a wide range of physical phenomena. We also draw attention to some particular problems and areas of opportunity in Colloidal Soft Matter Physics that represent promising perspectives for future investigations.

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Structure of colloidal gels at intermediate concentrations: the role of competing interactions

Cited by 20 publications

References 64 publications

Reversible Aggregation and Colloidal Cluster Morphology: The Importance of the Extended Law of Corresponding States

Reversible Aggregation and Colloidal Cluster Morphology: The Importance of the Extended Law of Corresponding States

Dynamic Scaling of Colloidal Gel Formation at Intermediate Concentrations

Colloidal Soft Matter Physics

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