Dynamic Light-Scattering Study of Aggregating and Gelling Colloidal Disks

Nicolai, Taco; Cocard, Stéphane

doi:10.1006/jcis.2001.7930

Cited by 65 publications

(78 citation statements)

References 28 publications

(30 reference statements)

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“…The volume fraction for the liquid-glass transition is given by eff Ϸ 0.5 and thus varies as lg ϳ h / l D ϰ I 1/2 where I is the ionic strength. Following the suggestion of Bonn et al ͓15͔,Levitz et al ͓13͔, by deionizing Laponite indeed found the evidence for a Wigner glass at very low ionic strengths consistent with the proposal of Bonn et al Nicolai and Cocard ͓18,19͔ have studied the aging at low concentrations of Laponite with added salt in the ergodic regime of aging. They observed that the scattered intensity increased with the waiting time.…”

Section: Introductionsupporting

confidence: 75%

Multiple nonergodic disordered states in Laponite suspensions: A phase diagram

et al. 2008

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We study the time evolution of different Laponite suspensions from a low-viscosity ergodic state to a viscoelastic nonergodic state over a wide range of volume fractions and salt contents. We find that the evolution of nonergodicity parameter ͑Debye-Waller factor͒ splits into two branches for all the samples, which correspond to two distinct dynamically arrested states. At moderately high salt concentrations, on the other hand, a third nonergodic state appears that is different from the above two nonergodic states. Measurement of the conductivity of Laponite solutions in pure water shows that the contribution of counterions in the ionic strength is considerable and their role should be taken into account in interpretations of aging dynamics and the phase diagram. Based on these data and available data in the literature, we propose a ͑nonequilibrium͒ phase diagram for Laponite suspensions.

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Section: Introductionsupporting

confidence: 75%

Multiple nonergodic disordered states in Laponite suspensions: A phase diagram

et al. 2008

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“…A fast relaxation mode in the dynamic scattering data has been frequently reported in relation to the liquid-glass transition, the glassy state and also for polymer coated clays 6,8,66 . In the present study on rigid and non-permeable gibbsite platelets, an essentially singleexponential fast mode in the VU intensity autocorrelation function is found also in the isotropic phase.…”

Section: Discussionmentioning

confidence: 99%

Dynamics of charged gibbsite platelets in the isotropic phase

et al. 2012

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We report on depolarized and non-depolarized dynamic light scattering, static light scattering, and steady shear viscosity measurements on interacting charge-stabilized gibbsite platelets suspended in dimethyl sulfoxide (DMSO). The average collective and (long-time) translational self-diffusion coefficients, and the rotational diffusion coefficient, have been measured as functions of the platelet volume fraction φ , up to the isotropic-liquid crystal (I/LC) transition. The non-depolarized intensity autocorrelation function, measured at low scattering wavenumbers, consists of a fast and a slowly decaying mode which we interpret as the orientationally averaged collective and translational self-diffusion coefficients, respectively. Both the rotational and the long-time self-diffusion coefficients decrease very strongly, by more than two orders of magnitude, in going from the very dilute limit to the I/LC transition concentration. A similarly strong decrease, with increasing φ , is observed for the inverse zero-strain limiting steady shear viscosity. With increasing φ , increasingly strong shear-thinning is observed, accompanied by a shrinking of the low shear-rate Newtonian plateau. The measured diffusion coefficients are interpreted theoretically in terms of a simple model of effective charged spheres interacting by a screened Coulomb potential, with hydrodynamic interactions included. The disk-like particle shape, and the measured particle radius and thickness polydispersities, enter into the model calculations via the scattering amplitudes. The interaction-induced enhancement of the collective diffusion coefficient by more than a factor of 20 at larger φ is well captured in the effective sphere model, whereas the strong declines both of the experimental translational and rotational self-diffusion coefficients are underestimated.

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“…A markedly different model recently proposed by Nicolai et al invokes aggregation in order to explain the process of gelation [30,31,32]. Weak attraction may lead to a slow aggregation of the particles even at low ionic strength.…”

Section: Introductionmentioning

confidence: 99%

Effective interaction of charged platelets in aqueous solution: Investigations of colloid laponite suspensions by static light scattering and small-angle x-ray scattering

Harnau

Rosenfeldt

et al. 2005

Phys. Rev. E

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We study dilute aqueous solutions of charged disk-like mineral particles (Laponite) by a combination of static light scattering (SLS) and small-angle x-ray scattering (SAXS). Laponite solutions are known to form gels above a certain critical concentration that must be described as non-equilibrium states. Here we focus on the investigation by SLS and SAXS at concentrations below gelation (c < 0.016 g/L) and at low concentrations of added salt (0.001 and 0.005 mM). Thus, we have obtained the scattering function of single Laponite platelets as well as the structure factor describing their interaction at finite concentration. A detailed analysis of the combined sets of data proves that the solutions are in a well-defined equilibrium state. Moreover, this analysis demonstrates the internal consistency and accuracy of the scattering functions obtained at finite concentrations. We find that Laponite particles interact through an effective pair potential that is attractive on short range but repulsive on longer range. This finding demonstrates that Laponite solutions exhibit only a limited stability at the concentration of added salt used herein. Raising the ionic strength to 0.005 mM already leads to slow flocculation as is evidenced from the enhanced scattering intensity at smallest scattering angles. All data strongly suggest that the gelation occurring at higher concentration is related to aggregation.

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Dynamic Light-Scattering Study of Aggregating and Gelling Colloidal Disks

Cited by 65 publications

References 28 publications

Multiple nonergodic disordered states in Laponite suspensions: A phase diagram

Multiple nonergodic disordered states in Laponite suspensions: A phase diagram

Dynamics of charged gibbsite platelets in the isotropic phase

Effective interaction of charged platelets in aqueous solution: Investigations of colloid laponite suspensions by static light scattering and small-angle x-ray scattering

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