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Phase behavior and crystallization kinetics of poly-12-hydroxystearic-coated polymethylmethacrylate colloids
S Auer1, W C K Poon, D Frenkel
1FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
Summary
Polymethylmethacrylate (PMMA) colloids, coated with poly-12-hydroxystearic (PHSA), exhibit softer interactions than hard spheres. This softness significantly accelerates their crystallization rate, offering new insights into colloidal systems.
Area of Science:
- Colloid Science
- Materials Science
- Physical Chemistry
Background:
- Polymethylmethacrylate (PMMA) colloids stabilized by poly-12-hydroxystearic (PHSA) are common model hard spheres.
- The PHSA coating introduces softness to particle interactions, deviating from ideal hard-sphere behavior.
Purpose of the Study:
- To numerically investigate the impact of PHSA coating on the phase behavior and crystallization kinetics of PMMA colloids.
- To reconcile experimental freezing data with theoretical models by considering the PHSA layer's influence.
Main Methods:
- Numerical simulations of PMMA colloids with PHSA coatings.
- Utilizing parameters derived from surface-force measurements on coated mica surfaces.
- Comparison with experimental data on freezing and crystallization.
Main Results:
- A larger PHSA layer thickness than previously reported is needed to match experimental freezing data.
- The discrepancy suggests potential slight charging of the PMMA particles.
- Crystallization rates for these slightly soft particles are approximately two orders of magnitude higher than for hard spheres.
Conclusions:
- The PHSA coating significantly affects the phase behavior and crystallization kinetics of PMMA colloids.
- The model requires adjustments (e.g., considering particle charge) to accurately represent experimental observations.
- Soft-sphere behavior in colloids can dramatically enhance crystallization rates.