Programmable actuation of liquid crystal elastomers via"living" exchange reaction

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Robotics

Background:

• Liquid crystal elastomers (LCEs) are crucial soft actuators and opto-mechanical materials.
• Mesogen orientation dictates LCE properties, but current alignment methods are complex or limited.
• Dynamic covalent bonds offer potential for material programmability.

Purpose of the Study:

• To synthesize an LCE with dynamic disulfide bonds for facile mechanical programming.
• To investigate the room-temperature "living" exchange reaction of disulfide bonds in bulk polymers.
• To demonstrate erasable and reprogrammable mesogen alignment and shape memory effects in LCEs.

Main Methods:

• Synthesis of LCEs incorporating dynamic disulfide bonds.
• Room-temperature mechanical programming via disulfide bond exchange reaction.
• Characterization of mesogen orientation, dynamic behavior, and shape memory properties.

Main Results:

• A novel LCE with dynamic disulfide bonds was successfully synthesized.
• A facile, catalyst-free, room-temperature mechanical programming method was established.
• The "living" exchange reaction of disulfide bonds at room temperature in bulk polymer was revealed, attributed to prolonged radical lifetimes.
• Erasable and reprogrammable mesogen orientation and shape memory effects were demonstrated.

Conclusions:

• The developed LCE offers a versatile platform for programmable soft actuators.
• The "living" disulfide bond exchange reaction provides a new mechanism for dynamic polymer network manipulation.
• This approach overcomes limitations of existing LCE programming methods, enabling advanced deployable devices.