Switching plastic crystals of colloidal rods with electric fields

Area of Science:

• Colloid science
• Materials science
• Soft matter physics

Background:

• Crystalline solids transition to liquids by losing positional and orientational order.
• Intermediate phases like liquid crystals and plastic crystals exhibit unique property combinations.
• Plastic crystals possess long-range positional order and short-range dynamic orientational order.

Purpose of the Study:

• To investigate the formation of three-dimensional plastic crystals and glasses in colloidal systems.
• To explore the influence of particle shape and interactions on phase behavior.
• To demonstrate the switchability of these plastic phases using external fields.

Main Methods:

• Quantitative three-dimensional studies of charged rod-like colloidal particles.
• Controlled manipulation of inter-particle repulsions relative to particle length.
• Application of electric fields to induce phase transitions.

Main Results:

• Formation of three-dimensional plastic crystals and glasses when particle repulsions significantly exceed particle length.
• These plastic phases exhibit long-ranged positional order and short-ranged dynamic orientational order.
• Reversible switching between plastic phases and full crystalline states using an electric field.

Conclusions:

• Charged rod-like colloids can form novel plastic crystalline and glassy states.
• Rotational dynamics play a crucial role in the phase behavior of these systems.
• The demonstrated electric-field switchability suggests potential applications in photonics.