Programming Orientation in Liquid Crystalline Elastomers Prepared with Intra-Mesogenic Supramolecular Bonds

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Robotics

Background:

• Aligned liquid crystalline elastomers (LCEs) exhibit significant directional stimuli-response, making them promising for robotics, medicine, and photonics.
• Traditional LCE alignment often involves multi-step reactions and mechanical or surface-enforced methods.
• Existing LCEs primarily rely on covalent bonds, limiting their programmability and response magnitude.

Purpose of the Study:

• To develop novel LCEs incorporating intra-mesogenic supramolecular bonds for enhanced properties.
• To investigate a facile preparation method using direct free-radical photopolymerization and mechanical alignment.
• To explore the impact of supramolecular bonds on thermomechanical strain and reprogrammability.

Main Methods:

• Synthesized LCEs via direct free-radical chain transfer photopolymerization of 11-oxybenzoic acid (11OBA) and a diacrylate liquid crystal monomer (C6M).
• Utilized a distinctive mechanical alignment mechanism for processing the synthesized LCEs.
• Investigated the effect of varying 11OBA concentrations on nematic order and thermomechanical strain.

Main Results:

• Incorporation of intra-mesogenic hydrogen bonds significantly increased nematic order achievable through mechanical programming.
• LCEs with higher 11OBA concentrations demonstrated superior thermomechanical strain compared to purely covalently bonded LCEs.
• The developed LCEs exhibited facile reprogramming capabilities, allowing heat-induced return to a polydomain state and reorientation.

Conclusions:

• Supramolecular bonds in LCEs enhance mechanical programming and thermomechanical performance.
• The direct photopolymerization and mechanical alignment method offers a simplified route to high-performance LCEs.
• These reprogrammable LCEs with supramolecular bonds are suitable for advanced applications, particularly as shape-deployable elements.