Colloidal Gels: Low‐Density Disordered Solid‐Like States

Trappe, Véronique; Sandkuehler, Peter

doi:10.1002/chin.200433293

Cited by 25 publications

(34 citation statements)

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“…The gel transition can also be reached by increasing the strength of particle-particle "bonds" at a given value of φ (Trappe et al, 2001;Trappe and Sandkühler, 2004). This remarkable feature of flocculated suspensions can be accounted for as a diminution of φ c with the strength of the interaction .…”

Section: Aggregation and Gelationmentioning

confidence: 98%

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Rheology and phase behavior of aggregating emulsions related to droplet-droplet interactions

Berli

2007

Braz. J. Chem. Eng.

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-The present work deals with the relationship between colloidal interactions and physical properties of emulsions, in particular rheology and gel transition. Experimental data on protein-stabilized oil-in-water emulsions are considered. In this system, the excess of protein in the aqueous phase yields reversible droplet aggregation by the mechanism of depletion. Thus both phase and flow behaviors can be controlled by changing protein concentration, ionic strength and temperature. Calculations of the potential of interaction between droplets are carried out in the framework of colloid science. Particular emphasis is placed on the role that droplet-droplet interaction plays in defining the morphology of the aggregates, hence the microstructure and finally, the bulk physical properties. This understanding offers new perspectives in the study of complex food systems.

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Section: Aggregation and Gelationmentioning

confidence: 98%

“…On the basis of the quantitative correlation given by Eq. (4), the diagram in Figure 3 incorporates the effects of ionic strength and temperature as well, thus providing a generalized description of the phase line (see also Trappe and Sandkühler, 2004). …”

Section: Phase Behaviormentioning

confidence: 99%

Rheology and phase behavior of aggregating emulsions related to droplet-droplet interactions

Berli

2007

Braz. J. Chem. Eng.

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“…At low densities, irreversible aggregation leads to fractal gels. At intermediate densities more compact porous structures are observed, whereas a homogeneous glass emerges when the solute occupies more than 50% of the volume (11,10,14,19).It has been proven that when colloidal particles are quenched into the gas-liquid phase separation region, gelation occurs as a consequence of dynamic arrest that interferes with phase separation (15, 18). After the quench, the system is thermodynamically unstable and strong density fluctuations set in, favoring the separation of the fluid into two coexisting phases.…”

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confidence: 99%

“…Colloidal gels find applications in synthetic colloid porous materials (1,2), functionalization of surfaces and films production (3,4), ceramics processing (5,6), protein assemblies (7,8), food science (9,10), and soft matter (11,12). Although they have been known for some time (13,14), it has only recently been understood that the colloidal gels arise as a result of arrested phase separation (15)(16)(17)(18).…”

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Arrested demixing opens route to bigels

Varrato

Michele

Belushkin

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

107

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Understanding and, ultimately, controlling the properties of amorphous materials is one of the key goals of material science. Among the different amorphous structures, a very important role is played by colloidal gels. It has been only recently understood that colloidal gels are the result of the interplay between phase separation and arrest. When short-ranged attractive colloids are quenched into the phase-separating region, density fluctuations are arrested and this results in ramified amorphous space-spanning structures that are capable of sustaining mechanical stress. We present a mechanism of aggregation through arrested demixing in binary colloidal mixtures, which leads to the formation of a yet unexplored class of materials--bigels. This material is obtained by tuning interspecies interactions. Using a computer model, we investigate the phase behavior and the structural properties of these bigels. We show the topological similarities and the geometrical differences between these binary, interpenetrating, arrested structures and their well-known monodisperse counterparts, colloidal gels. Our findings are supported by confocal microscopy experiments performed on mixtures of DNA-coated colloids. The mechanism of bigel formation is a generalization of arrested phase separation and is therefore universal.spinodal decomposition | DNA-coated colloids | programmable interactions | amorphous self-assembly T he properties of a self-assembled material are ultimately controlled by the interactions among its building blocks and by the conditions in which they are prepared. It is by tuning these two properties that different structures can be obtained. Shortranged attractive colloidal systems, for example, can form crystals, two glasses of different origin, or gels. The latter have great technological importance. Colloidal gels find applications in synthetic colloid porous materials (1, 2), functionalization of surfaces and films production (3, 4), ceramics processing (5, 6), protein assemblies (7, 8), food science (9, 10), and soft matter (11, 12). Although they have been known for some time (13,14), it has only recently been understood that the colloidal gels arise as a result of arrested phase separation (15-18).The gels are characterized by a ramified amorphous spacespanning structure that is capable of sustaining mechanical stress. The colloidal density plays a crucial role in the aggregation and therefore in the resulting structure. At low densities, irreversible aggregation leads to fractal gels. At intermediate densities more compact porous structures are observed, whereas a homogeneous glass emerges when the solute occupies more than 50% of the volume (11,10,14,19).It has been proven that when colloidal particles are quenched into the gas-liquid phase separation region, gelation occurs as a consequence of dynamic arrest that interferes with phase separation (15, 18). After the quench, the system is thermodynamically unstable and strong density fluctuations set in, favoring the separation of the fluid into two ...

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Structuring Water by Gelation

Hermansson¹

Food Materials Science

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Gels are of central importance for most semisolid food products. A gel can contain more than 99% water and still retain the characteristics of a solid. The network structure will determine whether the water will be firmly held or whether the gel will also have a major impact on the texture as well as diffusion of water and soluble cheeses, many desserts, sausages etc (see also Chapters 19 and 20). In whole foods, there is often a combination of colloidal structures and fragments of biological tissues or gel structures in combination with particles, emulsion and foam structures. This level of complexity of composite food structures will not be dealt with here. be demonstrated that biopolymer gel structures span a wide range of length scales and that length scale provides important information for the understanding of structure-related properties. Gelation can be approached from different directions, where the molecular approach has to be combined with colloidal models based on depletion mechanisms, classical aggregation-gelation theories or, more recently, mode-coupling theories based on dynamic arrest or jamming (Mezzenga et al. 2005). Incompatibility between biopolymers and gelation can lead to segregative or associative phase separation with mixed gel structures and properties varying according to the distribution of the phases (see Chapter 3).Since several mechanisms often come into play in a gelation process, the relative kinetics will determine the final structure and related properties. Nowadays we have tools that enable us to follow the development of the microstructure directly under the microscope giving insights of great interest to food engineering (see also Chapter 11). Here we will discuss not only structure formation but also structural breakdown. 255 behave more like a sponge, where water is easily squeezed out. The gel structure will compounds. Many food matrixes are based on colloidal gels such as yoghurts,

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Colloidal Gels: Low‐Density Disordered Solid‐Like States

Abstract: Theoretical chemistry Theoretical chemistry Z 0350 Colloidal Gels: Low-Density Disordered Solid-Like States -[58 refs.]. -(TRAPPE, V.; SANDKUEHLER, P.; Curr. Opin. Colloid Interface Sci. 8 (2004) 6, 494-500; Inst. Phys., Univ. Fribourg, CH-1700 Fribourg, Switz.; Eng.) -Lindner 33-293

Cited by 25 publications

References 1 publication

Rheology and phase behavior of aggregating emulsions related to droplet-droplet interactions

Rheology and phase behavior of aggregating emulsions related to droplet-droplet interactions

Arrested demixing opens route to bigels

Structuring Water by Gelation

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