Bond rupture between colloidal particles with a depletion interaction

Whitaker, Kathryn A.; Furst, Eric M.

doi:10.1122/1.4947043

Cited by 9 publications

(7 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In low-ionic-strength aqueous suspensions, electrostatic repulsion [32] gives rise to a potential barrier which limits the formation of solid-solid interparticle contacts. A shallow secondary minimum then permits the formation of weak interparticle bonds, that can be broken using optical traps [33,34]. In Supplementary Note 2 and Video we show that here, in contrast:…”

Section: Aging Without Microstructural Evolutionmentioning

confidence: 77%

“…significantly faster than other processes (diffusion, sedimentation). Indeed, typically, solid-solid contacts between micron-sized colloidal particles involve adhesion energies in the thousand kT [32] range, hence cannot be opened by thermal activation at room temperature [33,34]. So, at moderate or high packing fractions, such suspensions rapidly freeze into thermally irreversible structures.…”

Section: Contact-driven Agingmentioning

confidence: 99%

See 1 more Smart Citation

Contact and macroscopic ageing in colloidal suspensions

et al. 2020

Self Cite

View full text Add to dashboard Cite

The aging behaviour of dense suspensions or pastes at rest is almost exclusively attributed to structural dynamics. Here, we identify another aging process, contactcontrolled aging, consisting in the progressive stiffening of solid-solid contacts, after their initial formation rapidly arrests the microstructure. By combining rheometry, confocal microscopy, and particle-scale mechanical tests using laser tweezers, we demonstrate that this process governs the shear modulus aging of dense aqueous silica and polymer latex suspensions at moderate ionic strengths. We further show that contact-controlled aging becomes relevant as soon as Coulombic interactions are sufficiently screened out that the formation of solid-solid contacts is not limited by activation barriers. Given that this condition only requires moderate ion concentrations, contact-controlled aging should be generic in a wide class of materials, such as cements, soils, or 3D inks, thus questioning our understanding of aging dynamics in these systems.

show abstract

Section: Aging Without Microstructural Evolutionmentioning

confidence: 77%

Section: Contact-driven Agingmentioning

confidence: 99%

Contact and macroscopic ageing in colloidal suspensions

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…The shear and shear gradient-induced structures observed in Figure are correlated with the gel rheology. As with many colloidal gel systems, the thermoresponsive nanoemulsions exhibit yield stress and shear-thinning behavior, which can be described by the Herschel–Bulkley fluid model, σ = σ 0 + m γ ̇ n , where σ is the shear stress, σ 0 is the yield stress, m is the power law viscosity, n is the shear-thinning exponent, and γ ̇ is the shear rate. ,,− Empirically determined yield stress values and the range of shear stresses for r / R = 0.76–1.00 are outlined in Table . All shear stresses encountered in this study are above the gel’s yield stress; therefore, the observed behavior is fluid-like.…”

Section: Resultsmentioning

confidence: 99%

Migration and Morphology of Colloidal Gel Clusters in Cylindrical Channel Flow

Smith

Hsiao

2021

Langmuir

View full text Add to dashboard Cite

We report the cluster-level structural parameters of colloidal thermogelling nanoemulsions in channel flow as a function of attractive interactions and local shear stress. The spatiotemporal evolution of the gel microstructure is obtained by directly visualizing the dispersed phase near the edge of a cylindrical channel. We observe the flow of the nanoemulsion gels in a range of radial positions (r) and shear stresses between 70 and 220 Pa, finding that the r-dependent cluster sizes are due to a balance between shear forces that yield bonds and attractive interactions that rebuild the inter-colloid bonds. In addition, the largest clusters appear to be affected by confinement and accumulate toward the central axis of the channel, resulting in a volume fraction gradient. Cluster size and volume fraction variabilities are most prominent when the attractive interactions are the strongest. Specifically, a distinct transition from sparse, fluidized clusters near the walls to concentrated, large clusters toward the center is observed. These two structural states coincide with a velocity-based transition from higher shear rates near the walls to lower shear rates toward the center of the channel. We find a compounding effect where larger gel clusters, formed under strong attractions and low shear stresses, are susceptible to shear-induced migration that intensifies r-dependent heterogeneity and deviations in the flow behavior from predictive models.

show abstract

“…To date, no computational model has been used to investigate the role of hydrodynamic interactions in the mechanical response of arrested colloidal gels. and there is thus a need for a hydrodynamic theory to explain the observed relaxation modes [23,28]. Notably, Hurd et al [29] developed a systematic transport theory for normal modes in a harmonic lattice of colloidal particles immersed in a viscous medium and obtained predictions of the relaxation spectrum for dilute colloidal crystals.…”

Section: Introductionmentioning

confidence: 99%

“…Several experiments [5,22] have found that models neglecting hydrodynamic coupling fail to reproduce measured dynamics and friction coefficients. There is a need for a hydrodynamic theory to explain the observed relaxation modes [18,23]. Hurd et al [24] developed a systematic transport theory for normal-modes in a harmonic lattice of colloidal particles immersed in a viscous medium and obtained results for dilute colloidal crystals.…”

mentioning

confidence: 99%

Normal modes of weak colloidal gels

Varga

Swan

2018

Phys. Rev. E

View full text Add to dashboard Cite

The normal modes and relaxation rates of weak colloidal gels are investigated in calculations using different models of the hydrodynamic interactions between suspended particles. The relaxation spectrum is computed for freely draining, Rotne-Prager-Yamakawa, and accelerated Stokesian dynamics approximations of the hydrodynamic mobility in a normal mode analysis of a harmonic network representing several colloidal gels. We find that the density of states and spatial structure of the normal modes are fundamentally altered by long-ranged hydrodynamic coupling among the particles. Short-ranged coupling due to hydrodynamic lubrication affects only the relaxation rates of short-wavelength modes. Hydrodynamic models accounting for long-ranged coupling exhibit a microscopic relaxation rate for each normal mode, λ that scales as l −2 , where l is the spatial correlation length of the normal mode. For the freely draining approximation, which neglects long-ranged coupling, the microscopic relaxation rate scales as l −γ , where γ varies between three and two with increasing particle volume fraction. A simple phenomenological model of the internal elastic response to normal mode fluctuations is developed, which shows that long-ranged hydrodynamic interactions play a central role in the viscoelasticity of the gel network. Dynamic simulations of hard spheres that gel in response to short-ranged depletion attractions are used to test the applicability of the density of states predictions. For particle concentrations up to 30% by volume, the power law decay of the relaxation modulus in simulations accounting for long-ranged hydrodynamic interactions agrees with predictions generated by the density of states of the corresponding harmonic networks as well as experimental measurements. For higher volume fractions, excluded volume interactions dominate the stress response, and the prediction from the harmonic network density of states fails. Analogous to the Zimm model in polymer physics, our results indicate that long-ranged hydrodynamic interactions play a crucial role in determining the microscopic dynamics and macroscopic properties of weak colloidal gels.

show abstract

Bond rupture between colloidal particles with a depletion interaction

Cited by 9 publications

References 64 publications

Contact and macroscopic ageing in colloidal suspensions

Contact and macroscopic ageing in colloidal suspensions

Migration and Morphology of Colloidal Gel Clusters in Cylindrical Channel Flow

Normal modes of weak colloidal gels

Contact Info

Product

Resources

About