Observations of orientational ordering in aqueous suspensions of a nano-layered silicate

Fossum, Jon Otto; Gudding, E.; Fonseca, Davi de Miranda; Méheust, Yves; DiMasi, Elaine; Gog, T.; Venkataraman, C.

doi:10.1016/j.energy.2004.04.008

Cited by 36 publications

(28 citation statements)

References 23 publications

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“…Those findings are consistent with visual observations (Fossum et al, 2005), including observations through crossed polarizers: a birefringent region, coinciding with the region exhibiting orientational order (as inferred from the wide-angle X-ray scattering study), was observed. More recently, the existence of an isotropic-to-nematic transition in these systems has been corroborated by MRI studies of anisotropic water self-diffusion (de Azevedo et al, 2007).…”

Section: Introductionsupporting

confidence: 80%

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Phase behavior of platelet-shaped nanosilicate colloids in saline solutions – a small-angle X-ray scattering study

et al. 2007

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A study of polydisperse suspensions of fluorohectorite clay in saline solutions is presented. The suspended clay colloids consist of stacks of nanosilicate sheets several tenths of a nanometre thick. They are polydisperse both with respect to the number of stacked nanolayers and with respect to their extension along the sheets. Due to this polydispersity, a spontaneous gravity-induced vertical segregation occurs in the sample tubes and results in the presence of up to four different phases on top of each other. Precise characterization of the phase diagram of the samples as a function of salt concentration and vertical position in the tubes, based on small-angle X-ray scattering data, is presented. The vertical positions of the phase boundaries were monitored by analyzing the eccentricity of elliptic fits to iso-intensity cuts of the scattering images. The intensity profiles along the two principal directions of scattering display two power-law behaviors with a smooth transition between them and show the absence of positional order in all phases.

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Section: Introductionsupporting

confidence: 80%

“…When Fig. 5 is compared to the two previous estimates of the diagrams, one from visual observation, the other one from WAXS data [see DiMasi et al (2001) and Fossum et al (2005)], it is evident that the main features are consistent. The anisotropic gel found here is the nematic gel phase as identified from WAXS data.…”

Section: Resultsmentioning

confidence: 98%

Phase behavior of platelet-shaped nanosilicate colloids in saline solutions – a small-angle X-ray scattering study

et al. 2007

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“…These observations provided, in part, the experimental stimulus for the theory put forward by Onsager [1]. However, it took more than half a century before further experimental evidence for liquid crystal phase equilibria in suspensions of plate-like particles was obtained [5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Structure of the repulsive gel/glass in suspensions of charged colloidal platelets

Mourad

Byelov

Petukhov

et al. 2008

J. Phys.: Condens. Matter

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Rheological, optical and structural properties of colloidal suspensions of charge-stabilized gibbsite platelets across the sol-gel transition region are investigated. In this work we focus on samples with a low salt content (10 −4 M). While at a gibbsite concentration of 300 g l −1 , a nematic-columnar phase separation is observed, an arrested state with a nematic signature and highly elastic response has been observed for a concentration of 400 g l −1 . A temporal evolution of the structure of the arrested state, which leads to stronger interparticle correlations, has been observed on a timescale of 20 months. The results suggest that the arrested state develops into a glass with a columnar nematic structure.

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“…In recent years, nematic (Liu et al 2003;van der Beek & Lekkerkerker 2003Fossum et al 2005), columnar (Brown et al 1998;) and lamellar (Wang et al 2005) liquid crystal phases have been observed in suspensions of synthetic, charged, plate-like particles. These mineral liquid crystals (Gabriel & Davidson 2000;Davidson & Gabriel 2005) are quite promising as they have the potential of enhanced electrical, optical and magnetic properties and thermal stability compared to organic liquid crystal materials.…”

Section: Introductionmentioning

confidence: 99%

Gelation versus liquid crystal phase transitions in suspensions of plate-like particles

Mourad

Wijnhoven

Zand

et al. 2006

Phil. Trans. R. Soc. A.

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Gelation is a common effect in aqueous suspensions of charged colloidal clay platelets at concentrations as low as 1 wt%. However, in systems of charged gibbsite [Al(OH) 3 ] platelets, gelation can be delayed to concentrations as high as 50 wt% depending on the ionic strength. We investigated the phase behaviour of this system approaching the state of gelation in the delicate region between attractive and repulsive states that originate from competition between Coulomb repulsion and van der Waals attraction. As a function of the ionic strength, isotropic-nematic, nematic-columnar and isotropiccolumnar phase separations were observed. Moreover, compression by gravitational forces allowed us to observe phase separation that is arrested by gelation in the homogeneous suspensions.

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Observations of orientational ordering in aqueous suspensions of a nano-layered silicate

Cited by 36 publications

References 23 publications

Phase behavior of platelet-shaped nanosilicate colloids in saline solutions – a small-angle X-ray scattering study

Phase behavior of platelet-shaped nanosilicate colloids in saline solutions – a small-angle X-ray scattering study

Structure of the repulsive gel/glass in suspensions of charged colloidal platelets

Gelation versus liquid crystal phase transitions in suspensions of plate-like particles

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