Self-Assembly of Model Triblock Janus Colloidal Particles in Two Dimensions

Area of Science:

• Soft Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Triblock Janus particles exhibit complex self-assembly behaviors.
• Understanding nucleation and crystallization mechanisms is crucial for designing novel materials.
• Previous detailed models provide a basis for simplified simulations.

Purpose of the Study:

• To develop a simplified model for studying triblock Janus particle nucleation and self-assembly.
• To investigate the mechanism of nucleation and crystal growth.
• To compare simulation results with experimental data and existing models.

Main Methods:

• Development of a simplified two-dimensional effective-solvent model.
• Grand-canonical molecular dynamics simulations to calculate vapor-liquid equilibria and critical temperatures.
• Metadynamics simulations to investigate phase equilibria, nucleation mechanisms, and free energy barriers.

Main Results:

• A two-step nucleation mechanism was identified: fluid densification into a disordered cluster, followed by reorientation to form a crystalline nucleus.
• Crystal growth follows a two-step process: melting of less stable crystallites and recrystallization onto more stable ones.
• Softer potentials in the model favor the stabilization of open lattices like the kagome lattice.

Conclusions:

• The simplified model accurately reproduces experimental observations and previous simulation results for triblock Janus particle self-assembly.
• The developed model provides a computationally efficient approach to study nucleation and phase transitions in Janus particles.
• Softer potentials are more effective in stabilizing open crystalline structures compared to denser ones.