Actuating Liquid Crystals Rapidly and Reversibly by Using Chemical Catalysis.

Area of Science:

• Materials Science
• Chemical Engineering
• Soft Matter Physics

Background:

• Microtubules and motor proteins drive microscale actuation in living materials and reconstituted systems.
• Harnessing chemical energy is key for organizing soft matter, such as liquid crystals (LCs).
• Existing LC actuation methods are often fragile and difficult for technological applications.

Purpose of the Study:

• To develop a rapid and reversible method for controlling LC orientation at room temperature.
• To investigate the use of catalytic gas-surface reactions for microactuation.
• To explore the potential of chemical energy for functional LC actuation.

Main Methods:

• Utilized reactions between gaseous hydrogen (H2) and oxygen (O2) catalyzed by Palladium-Gold (Pd/Au) surfaces.
• Employed surface chemical analysis and computational chemistry to study reaction mechanisms.
• Demonstrated proof-of-concept microactuation of beads using the developed system.

Main Results:

• Achieved sub-second, reversible changes in LC orientation (perpendicular to planar) via H2/O2 reactions.
• Confirmed that H2 adsorption on Pd/Au surfaces drives LC reorientation.
• Showcased reversible LC orientation changes upon O2 exposure, restoring the initial state.
• Identified the influence of surface composition and reaction kinetics on LC dynamics.

Conclusions:

• Chemical energy and catalysis can be effectively used for reversible microscale actuation of functional LCs.
• The developed Pd/Au catalyzed H2/O2 reaction system offers a robust approach for LC control.
• This work provides new strategies for translating soft matter actuation to technological contexts.