Universal reshaping of arrested colloidal gels via active doping

Area of Science:

• Soft Matter Physics
• Materials Science
• Colloidal Science

Background:

• Colloids with short-range attraction are key building blocks for self-assembled materials.
• A major challenge is the rapid condensation into metastable colloidal gels.
• Controlling self-assembly is crucial for designing advanced materials.

Purpose of the Study:

• To investigate the use of active doping to control colloidal self-assembly.
• To prevent the formation of metastable colloidal gels.
• To guide systems towards thermodynamically favored crystalline structures.

Main Methods:

• Utilized computer simulations to model colloidal systems.
• Introduced a small fraction of purely repulsive self-propelled colloids (active doping).
• Analyzed systems with various anisotropic short-ranged pair interactions in 2D and 3D.

Main Results:

• Active doping successfully prevented metastable gel formation.
• Systems were directed towards their thermodynamically favored crystalline structures.
• A novel microphase of monodisperse finite-size crystallites was stabilized in mixtures of passive and active colloids, independent of interaction type.

Conclusions:

• Active doping provides a simple, robust, and generic pathway for directed colloidal self-assembly.
• This method enhances control over the formation of complex colloidal structures.
• Active forces are pivotal in directing colloidal self-assembly and designing hierarchical structures.