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Reactivity, swelling and aggregation of mixed-size silicate nanoplatelets
M Segad1, B Cabane, Bo Jönsson
1Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. MSegadMeehdi@lbl.gov M.Segad@gmail.com.
Nanoscale
|September 18, 2015
Summary
Montmorillonite platelet size influences swelling and tactoid formation in solutions. Smaller platelets (around 30 nm) prevent tactoid formation, affecting aggregation and swelling behavior.
Area of Science:
- Materials Science
- Colloid Science
- Clay Mineralogy
Background:
- Montmorillonite is crucial for technical uses, but its microstructure and inter-platelet forces are poorly understood.
- Platelet size variation in natural montmorillonite impacts swelling behavior in aqueous and salt solutions.
Purpose of the Study:
- Investigate the influence of montmorillonite platelet size on tactoid formation and swelling.
- Characterize the role of divalent counterions in tactoid formation and stability.
Main Methods:
- Analysis of montmorillonite from various natural sources.
- Observation of swelling behavior in water and salt solutions with varying divalent ion concentrations.
- Microstructural analysis focusing on tactoid formation and platelet aggregation.
Main Results:
- Tactoid formation, characterized by parallel platelet aggregation, is dependent on platelet size and divalent counterions.
- Very small montmorillonite nanoplatelets (∼30 nm) do not form tactoids, regardless of origin or ion concentration.
- The presence of small nanoplatelets in mixed-size systems hinders tactoid formation, reduces aggregation, and enhances swelling.
Conclusions:
- Montmorillonite tactoid formation and dissociation are reversible processes influenced by platelet size and ionic environment.
- Platelet size is a critical factor controlling montmorillonite microstructure, aggregation, and swelling properties.
- Understanding these relationships is key for optimizing montmorillonite in technical applications.
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