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Crystallization and gelation in colloidal systems with short-ranged attractive interactions
Andrea Fortini1, Eduardo Sanz, Marjolein Dijkstra
1Debye Institute for NanoMaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 13, 2008
Summary
We explored how attractive colloids crystallize, finding a sweet spot for faster crystal formation. This process involves dense liquid formation before crystal nucleation, with cluster fluids and gels appearing at different concentrations.
Area of Science:
- Colloid science
- Materials science
- Statistical mechanics
Background:
- Understanding phase transitions in colloidal systems is crucial for materials design.
- Nonequilibrium dynamics can significantly alter equilibrium phase behavior.
Purpose of the Study:
- To investigate the interplay between equilibrium and nonequilibrium phase diagrams in attractive colloidal systems.
- To identify conditions favoring enhanced crystallization and understand the underlying mechanisms.
Main Methods:
- Monte Carlo simulations
- Brownian dynamics simulations
Main Results:
- A window of enhanced crystallization was identified, limited by dynamics at high interaction strength and nucleation barriers at low interaction strength.
- A two-stage crystallization process was observed, involving dense liquid formation followed by crystal nucleation.
- At low packing fractions, a fluid of clusters was found, while higher fractions exhibited a percolating network (gelation) due to arrested phase separation.
- Cluster properties varied with interaction energy: crystalline at low energy, glassy at high energy.
Conclusions:
- The metastable gas-liquid binodal enhances crystallization through a two-stage process.
- Gelation arises from arrested phase separation, driven by crystallization or dynamics slowing.
- Colloid cluster morphology and dynamics are strongly dependent on interaction energy and packing fraction.
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