Influence of pyrophosphate or polyethylene oxide on the aggregation and gelation of aqueous laponite dispersions

Mongondry, Philippe; Nicolai, Taco; Tassin, Jean-François

doi:10.1016/j.jcis.2004.01.037

Cited by 134 publications

(182 citation statements)

References 12 publications

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“…Eqn (12) in the complete form was employed to fit the 10R5 and L35 data. The K 2 and the DH 2 values were quite uncertain due to the smooth x 2 variation in the interval of m P investigated as a consequence of the low K 2 (it is 1 AE 2 and 0.1 AE 1.4 kg mol À1 for 10R5 and L35, respectively).…”

Section: Modelling Experimental Enthalpiesmentioning

confidence: 99%

“…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%

“…The RD clay has the molecular formula 21 Si 8 (Mg 5.45 Li 0.4 )O 20 (OH) 4 Na 0.7 which is the unitary cell of the disk-like shape clay platelet having a diameter of about 25 nm and a thickness of 1 nm. 22 Each RD dispersion was prepared by gradually adding the necessary amount of powder to a known mass of water under continuous and vigorous stirring.…”

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confidence: 99%

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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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Section: Modelling Experimental Enthalpiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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show abstract

“…Similarly, the rate of gelation increases with solid concentration . The energy barrier caused by electrostatic repulsion between Laponite faces can be reduced by increasing Laponite solid concentration due to the increased ionic strength by counterions (Mongondry et al, 2004). As a result of the competition between electrostatic repulsion and VDW attraction, both nonergodic glass and gel state can be formed in very dilute dispersion with volume fraction of Laponite in the order of about 1% (Tanaka et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Surface chemistry and rheology of Laponite dispersions — Zeta potential, yield stress, ageing, fractal dimension and pyrophosphate

Leong

2015

Applied Clay Science

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“…This process can take up to 120 days for systems at 2 wt% Laponite but occurs much more quickly as Laponite concentration increases. [10] In this study, concentrations of 2.5 and 3.0 wt% were used. We explored several different concentrations of PEO for each Mw, ranging from 1 wt% to the highest concentration under which a homogenous clay-polymer solution could be made.…”

Section: Methodsmentioning

confidence: 99%

Laponite® and Laponite®‐PEO hydrogels with enhanced elasticity in phosphate‐buffered saline

Liu

Bhatia

2015

Polymers for Advanced Techs

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Hydrogels of the synthetic clay Laponite® and Laponite®-poly (ethylene oxide) (PEO) have long been studied as model systems to understand fundamental aspects of colloidal disks and colloid-polymer systems. More recently, these systems have been explored for a variety of biomedical applications. However, there is limited information in the literature on the fundamental properties of Laponite and Laponite-polymer gels at pH < 9. Here, we report the rheological behavior of Laponite and Laponite-PEO systems at biologically relevant conditions (e.g. physiological pH and ionic strength) and examine the effect of phosphate-buffered saline on the properties of the gel. Our results show that the elastic modulus of both Laponite and Laponite-PEO gels increases dramatically, in some cases by one order of magnitude or more, after immersing gels in phosphate-buffered saline. This may be due to an enhanced edge-face interaction between particles in buffered solutions, which would promote a long-lasting network structure of clay particles. These results are relevant to the design of clay-polymer gels and nanocomposites hydrogels for biomaterials applications.

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Influence of pyrophosphate or polyethylene oxide on the aggregation and gelation of aqueous laponite dispersions

Cited by 134 publications

References 12 publications

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

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

Surface chemistry and rheology of Laponite dispersions — Zeta potential, yield stress, ageing, fractal dimension and pyrophosphate

Laponite® and Laponite®‐PEO hydrogels with enhanced elasticity in phosphate‐buffered saline

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