Ageing behaviour spanning months of NaMt, hectorite and Laponite gels: Surface forces and microstructure – A comprehensive analysis

Leong, Yee-Kwong; Liu, Pengfei; Clode, Peta L.; Liu, Jishan

doi:10.1016/j.colsurfa.2021.127543

Cited by 13 publications

(21 citation statements)

References 78 publications

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“…1−3 The same explanation goes with the structural rejuvenation process during the stepdown in the shear rate. 3 We will present here direct evidence that this is indeed the case. In the aging test, the gels were first presheared to an equilibrium breakdown state and then left to recover undisturbed except at the preset times for the yield stress measurement.…”

Section: ■ Introductionmentioning

confidence: 59%

“…The structure formed during aging at rest and in shear will be different. 3,4,6 The timescale of the structural rejuvenation process is also quite different, in months and years in aging 3,21 and in minutes in shear. 4,6 The EDL interaction energy per unit area W EDL between two perfectly aligned, similarly charged, parallel plates under the weak overlap approximation is given by 28 Ä…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…If this repulsive force gets to become very strong due to a change in orientation (a slight change in the angle of interaction) caused by interactions with mobile neighboring platelets, it can break the bond and move and orient the platelets in position to form a stronger bond. 3 Under certain surface chemistry conditions such as at high salt concentration, even quite well-aligned face−face interaction could lead to bonding. 3 Under some other conditions, particle bonding may not be possible even when face−face or edge−face interaction configurations are highly misaligned, as the energy barrier may still be too high.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Direct Evidence of Electric Double Layer (EDL) Repulsive Force Being Responsible for the Time-Dependent Behavior of Clay Gels in the Structural Rejuvenation Mode

Leong

2024

J. Phys. Chem. B

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A strong EDL repulsive force is needed to accentuate the time-dependent behavior of charge and shape anisotropic clay gels at the stepdown shear rate. This force was strengthened by P2O7 4– adsorption, increasing the negative charge density of the clay particles. At the stepdown shear rate of 10 s–1, it is strong enough to disrupt the flow-aligned structure attained at 1000 s–1 and orient the particles to form more bonds. The resultant outcome is stepdown shear stress increasing with time until these structure disruption and bond formation processes reach an equilibrium state. The number of lower energy approach configurations (−ve face – +ve edge) for bonding is reduced by the strengthened EDL repulsive force, slowing the bonding process. The time to reach the equilibrium stepdown shear stress value increased initially and then decreased and became zero at a high negative charge density where the charge anisotropy of the particles no longer exists. The need of a sufficiently strong EDL repulsive force for the display of time-dependent behavior is true for all clay gels: Laponite, hectorite, NaMnt, sepiolite, and kaolin gels. The untreated NaMnt gel already displayed time-dependent behavior as its EDL repulsive force is sufficiently strong. The same EDL-control time-dependent behavior was obtained if pH was used to vary the negative charge density of the clay particles.

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Section: ■ Introductionmentioning

confidence: 59%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

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Direct Evidence of Electric Double Layer (EDL) Repulsive Force Being Responsible for the Time-Dependent Behavior of Clay Gels in the Structural Rejuvenation Mode

Leong

2024

J. Phys. Chem. B

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“…Furthermore, the electrical double layer, in the presence of salt, is contracted. This decreases the repulsion between the particles to allow them to get closer to each other (Leong et al 2021). These two phenomena lead to a stronger gel.…”

Section: Analysis Of the Model Obtained For The Storage Modulus G ′mentioning

confidence: 97%

Mixture design applied to the rheology of clay gel mixtures

et al. 2022

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We used mixture design to predict rheological parameters, namely the storage and loss modulus $$G'$$ G ′ and $$G''$$ G ′ ′ and the critical stress $$\sigma _{c}$$ σ c , of mixtures of Laponite EP and bentonite clay. Laponite EP is an organically coated laponite displaying unusual rheological behaviour compared to its unmodified form. We examined the effect of salt (magnesium chloride) and of surfactant (Tween 20) varying the pH between 4 and 9. We found reliable complex models with significant higher order terms showing that the rheological behaviour of the gels was not a function of each single compound, but instead the result of multiple interactions. Such interactions had an antagonistic effect on $$G'$$ G ′ and $$G''$$ G ′ ′ . Stronger gels were found at low concentrations of magnesium chloride and Tween 20. The gel stability in response to stress increased with the amount of Tween 20, but decreased with magnesium chloride. Such distinct behaviour may be the result of interactions between the platelet charges and the different components, as well as salting in versus salting out effects. We identified the conditions for which the values of $$G'$$ G ′ were suitable for agrochemical products. The method presented here is a quick and reliable approach to formulate products with targeted rheological properties.

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“…1035,1036 Its swelling behavior in aqueous solution is another interesting characteristic of LAPONITE®. 1037–1040 Concentration and ion strength are determinants for the dispersion, aggregation, and coagulation of LAPONITE® in solution. Small molecules can be accordingly sequestered in the interlayer space, inter-particle space, or surface of LAPONITE® particles, such as steroids, 1041 therapeutic drugs, 1042 and antibiotics.…”

Section: Biomedical Applications Of Silicon-containing Biomaterialsmentioning

confidence: 99%

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

Chen,

Zhang,

Duan

et al. 2024

Chem. Soc. Rev.

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Ageing behaviour spanning months of NaMt, hectorite and Laponite gels: Surface forces and microstructure – A comprehensive analysis

Cited by 13 publications

References 78 publications

Direct Evidence of Electric Double Layer (EDL) Repulsive Force Being Responsible for the Time-Dependent Behavior of Clay Gels in the Structural Rejuvenation Mode

Direct Evidence of Electric Double Layer (EDL) Repulsive Force Being Responsible for the Time-Dependent Behavior of Clay Gels in the Structural Rejuvenation Mode

Mixture design applied to the rheology of clay gel mixtures

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

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