Probing the Morphology of Laponite Clay Colloids by Atomic Force Microscopy

Balnois, Eric; Durand-Vidal, Serge; Levitz, Pierre

doi:10.1021/la0340908

Cited by 121 publications

(133 citation statements)

References 30 publications

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“…However, it has become possible to visualize directly the Laponite particles by various techniques as AFM or electron microscopy. From these micrographs it is obvious that Laponite exhibits a considerable polydispersity [34,35,36,37]. A second point that is common to many experimental study is the analysis of obvious non-equilibrium states reached after passing the gel line.…”

Section: Introductionmentioning

confidence: 98%

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: Introductionmentioning

confidence: 98%

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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“…is a synthetic hectorite clay with well-controlled dimensions (disc-shaped particles of mean diameter of 30 nm and thickness 1 nm) that does not form the strongly layered structures, which is common in natural clay [13][14][15]. It also presents the high structural regularity and purity.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Elastomeric Polyurethane-Laponite Nanocomposite

Mishra

Chattophadyay

Nando

et al. 2008

Designed Monomers and Polymers

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Polyurethanes (PU) are a group of versatile polymers finding a lot of engineering uses due to their favorable and tunable properties and processing advantages. Although considerable amount of work has been reported on the polyurethane-montmorilonite nanocomposite, there is not much literature available on the polyurethane-laponite clay nanocomposite. In this paper, we report the modification of laponite clay with dodecylamine hydrochloride by an ion-exchange process and in situ preparation of polyurethane-laponite clay nanocomposites. Clay incorporation into the polyurethane matrix increased the storage modulus and this trend continues with an increase in clay loading. Thermal stability of the composites was also increased with the clay loading. It was found that modified clay shows a tendency to be preferentially associated with the soft segment of polyurethane; however, the hard domain ordering gets significantly prejudiced at a lower clay loading. On the other hand, at higher clay loading, a nucleating tendency of clay aggregate was observed. The change in length scale of clay aggregation is demonstrated with SEM fractographs of the PU-clay nanocomposites.

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“…2 ) is a colorless synthetic hectorite prepared via hydrothermal methods which is mainly used as a rheological additive. It consists of very small ( L = 10-40 nm), mostly delaminated tactoids, [ 29 ] that are known to form house-of-card-type structures even in diluted dispersions. [ 30 ] Dedicated to Professor Bernd Harbrecht on the occasion of his 60th birthday.…”

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confidence: 99%