Following the nucleation pathway from disordered liquid to gyroid mesophase

Area of Science:

• Materials Science
• Soft Matter Physics
• Crystallography

Background:

• Mesophases exhibit intermediate order between liquids and crystals.
• The gyroid mesophase, featuring interpenetrated chiral networks, is valuable for photonics.
• Nucleating the gyroid mesophase from a liquid state is experimentally challenging.

Purpose of the Study:

• To elucidate the reaction coordinate and transition states for gyroid mesophase nucleation from a liquid.
• To identify key molecular descriptors for tracking gyroid formation.
• To provide a foundation for designing additives that facilitate gyroid mesophase formation.

Main Methods:

• Molecular simulations of a mesogenic binary mixture.
• Analysis of transition states and critical nuclei.
• Committor analysis using bond-order parameters.

Main Results:

• Gyroid nuclei at transition states are positionally disordered and non-compact, correlating with low liquid-gyroid interface free energy.
• A combination of bond-order parameters for the minor component effectively describes the liquid-to-gyroid transition.
• Committor analysis indicates that improved reaction coordinates should include ordering of both interpenetrated networks and the major component.

Conclusions:

• This study presents the first investigation into the reaction coordinate and critical nuclei for mesophase formation from an amorphous phase.
• The findings offer a deeper understanding of gyroid nucleation mechanisms.
• The results pave the way for targeted design of additives to control mesophase formation for photonic applications.