Rheology of attractive emulsions

Datta, Sujit S.; Gerrard, Dustin D.; Rhodes, Travers; Mason, Thomas G.; Weitz, David A.

doi:10.1103/physreve.84.041404

Cited by 121 publications

(125 citation statements)

References 24 publications

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“…Furthermore, by including the more accurate microscopic picture, the predictions of P(f) and G 0 p (f) for disordered colloidal emulsions can be rened, and predictions of the yield shear stress s y (f) could also be obtained. 20 Exploring the implications of this model in relation to aging and dynamical heterogeneity effects, 25 large-amplitude pre-shearing conditions, 28 frequency-dependent and strain-rate dependent rheology, 29 attractive interactions, 30 and polydispersity in the distribution of droplet radii remains on the frontier.…”

Section: Resultsmentioning

confidence: 99%

Crossover between entropic and interfacial elasticity and osmotic pressure in uniform disordered emulsions

Mason

Scheffold

2014

Soft Matter

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Section: Resultsmentioning

confidence: 99%

Crossover between entropic and interfacial elasticity and osmotic pressure in uniform disordered emulsions

Mason

Scheffold

2014

Soft Matter

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“…In parallel, systematic experiments are necessary at these packing fractions in order to further test our findings. While there have been recent experiments probing static properties of jammed attractive assemblies [31] or their shear moduli [32], more detailed rheological studies of these dense fragile networks are necessary.…”

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confidence: 99%

Impact of Attractive Interactions on the Rheology of Dense Athermal Particles

2014

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Using numerical simulations, the rheological response of an athermal assembly of soft particles with tunable attractive interactions is studied in the vicinity of jamming. At small attractions, a fragile solid develops and a finite yield stress is measured. Moreover, the measured flow curves have unstable regimes, which lead to persistent shearbanding. These features are rationalized by establishing a link between the rheology and the inter-particle connectivity, which also provides a minimal model to describe the flow curves.PACS numbers: 83.10. Rs,83.60.Wc,66.20.Cy In nature, soft disordered solids occur in different forms (eg. gels, emulsions, colloids, foams, grains etc) across a wide range of packing fractions φ, which is made possible by the tuning of particle interactions. The flow properties of these soft materials have been harnessed for various applications, e.g. in the food or the chemical industry. Thus, understanding the role of particle interactions and the corresponding mechanisms which lead to observed rheological behaviour is an important recurrent theme.For non-Brownian suspensions of frictionless repulsive spheres, it is observed that ramping up the packing fraction results in the occurrence of jamming at φ = φ J [1, 2]. The rheological signature of the onset of jamming is the development of a finite yield stress at φ J [3]. For Brownian suspensions of such particles, it has been shown that a yield stress exists at φ < φ J , due to the presence of thermal vibrations [4]. A similar systematic investigation of how the jamming paradigm is changing upon the introduction of attractive particle interactions is still missing. It is known that at smaller φ, such systems do exhibit finite yield stress [5,9,19,24]; but, a quantitative bridge with the jamming scenario needs to be developed.Such studies are also needed since shear-banding, the phenomenon of spatially inhomogeneous flows observed in many soft yield-stress fluids [6, 7], has often been attributed to attractive interactions [8,9]. In general, persistent occurrence of shear-bands has been linked to nonmontonic constitutive laws leading to flow instabilities [6, 10] (e.g. in micelles [11]). It is not known how interparticle attractions could result in such instabilities.Conceptually, one can imagine the steady flowing state to be a regime where there is a continuous competition between the rupturing induced by shear and processes that try to restore local structure. Theoretical models suggest that non-monotonic flow curves can occur due to long-lived local fluidizations when the post-rupture restructuring takes a very long time [12][13][14]. However, experiments and numerical simulations have shown that for φ > φ J , no such instabilities occur in the flow curve for either repulsive or attractive systems [15][16][17][18]. The question now arises whether for φ < φ J , a short-ranged attraction which introduces a new lengthscale for structure formation leads to longer restoration timescales and if this is indeed the origin of a shear banding ...

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“…In particular, softness of the interactions and the particles has been shown to dramatically alter nonergodic-to-ergodic transitions leading to multiple glassy states [Stiakakis et al (2002); Stiakakis et al (2005); Bartsch (2002, 2003); Datta et al (2011);Truzzolillo et al (2011Truzzolillo et al ( , 2013a; Wiemann et al (2012)]. In our work, we employed multiarm star polymers as model soft colloids encompassing the two main macroscopic response features of entropically interacting soft particles, namely, squeezing and interpenetration [Bonnecaze and Cloitre (2010); Vlassopoulos and Fytas (2010)].…”

Section: Introductionmentioning

confidence: 99%

Depletion gels from dense soft colloids: Rheology and thermoreversible melting

Truzzolillo¹,

Vlassopoulos²,

Munam³

et al. 2014

Journal of Rheology

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SynopsisUpon addition of small nonadsorbing linear polymers, colloidal glasses composed of large hard spheres melt and eventually revitrify into the so-called attractive glass regime. We show that, when replacing the hard spheres by star polymers representing model soft particles, a reentrant gel is formed. This is the result of compression and depletion of the stars due to the action of the osmotic pressure from the linear homopolymers. The viscoelastic properties of the soft dense gel were studied with emphasis on the shear-induced yielding process, which involved localized breaking of elements with a size of the order of the correlation length. Based on these results, a phenomenological attempt was made at describing the universal rheological features of colloid/nonadsorbing polymer mixtures of varying softness. The star gel was found to undergo thermoreversible melting, despite the fact that conventional hard-sphere depletion gels are invariant to heating. This phenomenon is attributed to the hybrid internal microstructure of the stars, akin to a dry-to-wet brush transition, and is characterized by slow kinetics, on the time scale of the osmotic gel formation process. These results may be useful in finding generic features in colloidal gelation, as well as in the molecular design of new soft composite materials. V C 2014 The Society of Rheology. [http://dx

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Rheology of attractive emulsions

Cited by 121 publications

References 24 publications

Crossover between entropic and interfacial elasticity and osmotic pressure in uniform disordered emulsions

Crossover between entropic and interfacial elasticity and osmotic pressure in uniform disordered emulsions

Impact of Attractive Interactions on the Rheology of Dense Athermal Particles

Depletion gels from dense soft colloids: Rheology and thermoreversible melting

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