Dissociation of thixotropic clay gels

Martin, Céline; Pignon, Frédéric; Piau, Jean‐Michel; Magnin, Albert; Lindner, Peter; Cabane, Bernard

doi:10.1103/physreve.66.021401

Cited by 95 publications

(120 citation statements)

References 38 publications

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“…As a consequence of this, no well-defined phases or phase transitions can be identified anymore. The observations made by Nicolai et al [29] are in agreement with a study of Martin et al [33]. Hence, the origins of the sol-gel transition have not yet been fully clarified despite of more than two decades of research.…”

Section: Introductionsupporting

confidence: 69%

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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Section: Introductionsupporting

confidence: 69%

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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“…The same identical protocol has been strictly followed for the preparation of each sample, fundamental condition to obtain reliable and reproducible results 23 . All our samples after a few minutes reach a constant value of pHC10, as measured in 42,43 . At this pH the rim charges are positive 44 .…”

Section: Discussionmentioning

confidence: 99%

Glass–glass transition during aging of a colloidal clay

et al. 2014

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Colloidal suspensions are characterized by a variety of microscopic interactions, which generate unconventional phase diagrams encompassing fluid, gel and glassy states and offer the possibility to study new phase and/or state transitions. Among these, glass-glass transitions are rare to be found, especially at ambient conditions. Here, through a combination of dilution experiments, X-ray photon correlation spectroscopy, small angle X-ray scattering, rheological measurements and Monte Carlo simulations, we provide evidence of a spontaneous glass-glass transition in a colloidal clay. Two different glassy states are distinguished with evolving waiting time: a first one, dominated by long-range screened Coulombic repulsion (Wigner glass) and a second one, stabilized by orientational attractions (Disconnected House of Cards glass), occurring after a much longer time. These findings may have implications for heterogeneously charged systems out-of-equilibrium and for applications where a fine control of the local order and/or long term stability of the amorphous materials are required.

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“…The polymer adsorption onto RD clay is an issue of great relevance because polymers [4][5][6] are employed to inhibit the aggregation and gelation of suspensions due to the formation of steric barriers the efficiency of which depends both on the concentration and the molecular weight (Mw) of the macromolecule. Furthermore, the coated particles may assume peculiar characteristics generating novel materials like nanocomposites [7][8][9] of clay and polymers.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature

Lisi

Lazzara

Lombardo

et al. 2005

Phys. Chem. Chem. Phys.

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The adsorption thermodynamics of copolymers, based on ethylene oxide (EO) and propylene oxide (PO) units, at the laponite (RD) clay/liquid interface was determined at 298 K. The copolymer nature was tuned at molecular level by changing the hydrophilicity, the architecture and the molecular weight (Mw) keeping constant the EO/ PO ratio. Polyethylene (PEGs) and polypropylene (PPGs) glycols with varying Mw and their mixture were also investigated to discriminate the role of the EO and the PO segments in the adsorption process. Enthalpies of transfer of RD, at fixed concentration, from water to the aqueous macromolecule solutions as functions of the macromolecule molality were determined. They were treated quantitatively by means of a model based on two equilibria: (1) one-to-one binding between the macromolecule and the site on the solid and (2) two-to-one binding following which one macromolecule interacts with another one adsorbed onto the solid. The good agreement between the equilibrium constants obtained from calorimetry and those determined from kinetic experiments confirmed the reliability of the experimental and theoretical approaches. Almost all of the systems investigated are highlighted by the one-to-one binding; the L35 and 10R5 systems present both equilibria. The insights provided by the thermodynamics of adsorption of their homopolymers onto RD were fruitful in obtaining detailed information on the nature of the forces involved between RD and the copolymers. The data obtained in the present work clearly evidenced that for comparable polymer Mw, PPG is more suitable in building up a steric barrier around the RD particles and, indeed, exhibits several advantages and no drawbacks. Moreover, the parent copolymers may properly functionalize the RD surface by exploiting both their high affinity to the solid surface and the ability to self-assemble onto it as L35 and 10R5 clearly showed.

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Dissociation of thixotropic clay gels

Cited by 95 publications

References 38 publications

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

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

Glass–glass transition during aging of a colloidal clay

Adsorption of triblock copolymers and their homopolymers at laponite clay/solution interface. Role played by the copolymer nature

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