Reprogramming Photoresponsive Liquid Crystalline Elastomer via Force-Directed Evaporation

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Robotics

Background:

• Thermoresponsive liquid crystalline elastomers (LCEs) enable remote and spatio-temporal control of actuation when incorporating photothermal agents.
• Current methods fix light responsiveness and actuation behaviors during initial network formation, limiting post-synthesis modifications.

Purpose of the Study:

• To develop a method for programming photoresponsive LCEs after their synthesis.
• To enable reprogramming of actuation modes and photoresponsiveness in LCEs.
• To achieve complex, spatio-selective actuations and adapt LCEs for 3D printing applications.

Main Methods:

• Utilized a force-directed evaporation technique for post-synthesis programming of LCEs.
• Introduced and removed photothermal agents via swelling cross-linked LCEs in specific solutions.
• Redefined molecular order by re-evaporating solvent under imposed force, erasing previous alignment.

Main Results:

• Successfully demonstrated the ability to introduce and erase photoresponsiveness in fully cross-linked LCEs.
• Showcased simultaneous programming/reprogramming of actuation mode and responsiveness.
• Extended the approach to 3D printed LCEs for creating geometrically complex shape-changing devices.

Conclusions:

• The developed 'one stone, two birds' strategy allows for versatile post-synthesis control over LCE properties.
• This method enables dynamic reprogramming of LCEs for tunable actuation and responsiveness.
• The approach is compatible with 3D printing, opening avenues for advanced soft robotic applications.