Dispersion state and rheology of hectorite particles in water over a broad range of salt and particle concentrations

Kimura, Hiroshi; Sakurai, Mikito; Sugiyama, Taiki; Tsuchida, Akira; Okubo, Tsuneo; Masuko, Tōru

doi:10.1007/s00397-011-0532-7

Cited by 24 publications

(4 citation statements)

References 24 publications

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“…On the other hand, bond formation through edge-face, face-face and edge-edge interactions are predicted at varying salt concentrations in a dispersing medium of pH> 7 [28,29]. The coagulation process becomes more complicated with increasing platelet concentration in the presence of salt and a house of cards (HoC) structure is frequently invoked to explain the nature of gel networks [30][31][32][33][34][35]. Surprisingly, the experimental evidence of such predicted microstructures is very limited.…”

Section: Introductionmentioning

confidence: 99%

Effect of electrolytes on the microstructure and yielding of aqueous dispersions of colloidal clay

Ali

Bandyopadhyay

2016

Soft Matter

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Na-montmorillonite is a natural clay mineral and is available in abundance in nature. The aqueous dispersions of charged and anisotropic platelets of this mineral exhibit non-ergodic kinetically arrested states ranging from soft glassy phases dominated by interparticle repulsions to colloidal gels stabilized by salt induced attractive interactions. When the salt concentration in the dispersing medium is varied systematically, viscoelasticity and yield stress of the dispersion show non-monotonic behavior at a critical salt concentration, thus signifying a morphological change in the dispersion microstructures. We directly visualize the microscopic structures of these kinetically arrested phases using cryogenic scanning electron microscopy. We observe the existence of honeycomb-like network morphologies for a wide range of salt concentrations. The transition of the gel morphology, dominated by overlapping coin (OC) and house of cards (HoC) associations of clay particles at low salt concentrations to a new network structure dominated by face-face coagulation of platelets, is observed across the critical salt concentration. We further assess the stability of these gels under gravity using electroacoustics. This study, performed for concentrated clay dispersions for a wide concentration range of externally added salt, is useful in our understanding of many geophysical phenomena that involve the salt induced aggregation of natural clay minerals.

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Section: Introductionmentioning

confidence: 99%

Effect of electrolytes on the microstructure and yielding of aqueous dispersions of colloidal clay

Ali

Bandyopadhyay

2016

Soft Matter

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“…2(b)). At salt concentrations [NaCl] higher than 0.01 M, the shear stress clearly increased as the salt concentration increased and saturated at [NaCl] = 0.1 M. The increase of shear stress would be due to the formation of a house-of-cards structure in the presence of salt, because of weakening of electrostatic repulsive force between the stevensite mineral (Kimura et al, 2011). Surprisingly, the maximum stress-values were lower than those under an electric field larger than 6.0 V/mmDC.…”

Section: Resultsmentioning

confidence: 93%

Changes of viscosity in stevensite aqueous dispersions with application of an electric field of the order of a few V/mm

Kimura

Nakashima

Takahashi

et al. 2015

Applied Clay Science

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“…This fact was confirmed since smaller shear stresses were reported for MMT suspensions at the same solid concentration [29] than HTgel@10. The expansion of the electrical double layer of HT particles prevents the formation of a "house-of-cards" network [30]. Therefore, the individually dispersed suspension make the particles freely flow under stress conditions without forming defined hysteresis loops (0D, 1D, 1M).…”

Section: Rheology and Phmentioning

confidence: 99%

Assessment of Hectorite/Spring Water Hydrogels as Wound Healing Products

García‐Villén

Sánchez-Espejo

Borrego-Sánchez

et al. 2020

The 1st International Electronic Conference on Pharmaceutics

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Wound healing treatments continue to be a medical challenge, since complications usually lead to chronicization and comorbidities. Natural inorganic ingredients such as clays have been demonstrated to exert useful activities in this regard. Hectorite is a smectite clay with desirable rheology due to its layered structure and remarkable swelling capacity. These properties make it an appropriate excipient for semisolid systems. Nonetheless, the biocompatibility of natural hectorite has been scarcely addressed; the majority of studies centered on synthetic or functionalized hectorites. The aim of this study was to prepare and characterize a hectorite/spring water hydrogel. The hectorite clay mineral was subjected to a solid-state characterization, while the hydrogel (HTgel@10) was evaluated in terms of rheology, pH and in vitro biocompatibility and wound healing. Results demonstrated that the hectorite possessed a remarkable purity (84% w/w of hectorite), very similar to that of similar pharmaceutical excipients. HTgel@10 showed a non-Newtonian, viscoplastic to pseudoplastic profile and a stable pH for 12 months. In vitro tests reported that the hectorite and the HTgel@10 were biocompatible (cellular viability ≥ 70%). Specifically, the hectorite used in this study was more biocompatible toward fibroblasts than Veegum® HS. The in vitro wound healing test revealed that HTgel@10 was able to favor the wound closure. Therefore, hectorite/spring water hydrogels could be considered as potential wound healing formulations with remarkable stability and safety.

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Dispersion state and rheology of hectorite particles in water over a broad range of salt and particle concentrations

Cited by 24 publications

References 24 publications

Effect of electrolytes on the microstructure and yielding of aqueous dispersions of colloidal clay

Effect of electrolytes on the microstructure and yielding of aqueous dispersions of colloidal clay

Changes of viscosity in stevensite aqueous dispersions with application of an electric field of the order of a few V/mm

Assessment of Hectorite/Spring Water Hydrogels as Wound Healing Products

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