Metal-Ligand Bonds Based Reprogrammable and Re-Processable Supramolecular Liquid Crystal Elastomer Network.

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Matter Physics

Background:

• Dynamic covalent bonds in liquid crystal elastomers (LCEs) enable network rearrangement and reversible actuation but are difficult to recycle.
• Supramolecular interactions offer recyclability but lack stability for programmed alignment under external stimuli.
• A significant challenge lies in creating LCEs with both supramolecular-like exchangeability and covalent bond-level stability.

Purpose of the Study:

• To develop a novel liquid crystal elastomer (LCE) with both network exchangeability and stable programmed alignment.
• To utilize metal-ligand bonds as crosslinking points to achieve these properties.
• To demonstrate the material's potential for fabricating versatile actuators.

Main Methods:

• Synthesized LCEs utilizing metal-ligand bonds as crosslinking points.
• Investigated the dynamic properties of the metal-ligand bonds at different temperatures.
• Demonstrated the ability to repeatedly encode and maintain mesogen alignment.
• Showcased reshaping capabilities via solution casting after complete bond dissociation.

Main Results:

• Metal-ligand crosslinked LCEs exhibit stable mesogen alignment below the bond dissociation temperature.
• The bond exchange rate is sufficiently slow for programming and actuation below dissociation temperature.
• Complete dissociation of metal-ligand bonds at high temperatures allows for complete network dissolution and reshaping.
• The developed LCEs were successfully fabricated into functional actuators.

Conclusions:

• Metal-ligand bonds provide a unique crosslinking strategy for LCEs, balancing stability and recyclability.
• This approach overcomes the limitations of traditional dynamic covalent and supramolecular LCEs.
• The resulting LCEs are highly versatile for creating advanced soft actuators and programmable materials.