On-demand photo-controlled motion enabled by solvent-driven mesogen alignment switch

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Robotics

Background:

• Azobenzene mesogens are key photo-responsive materials for soft robots due to trans-cis isomerization.
• Mesogen alignment in polymer networks dictates photo-actuation but is typically fixed after initial processing.
• Limited diversity in actuation modes arises from the difficulty in altering pre-determined mesogen alignment.

Purpose of the Study:

• To introduce a facile solvent treatment method for reversibly altering mesogen alignment in polymer networks.
• To enable tunable and diverse photo-actuation behaviors in azobenzene-based materials.
• To demonstrate novel applications of photo-responsive membranes in liquid environments.

Main Methods:

• Preparation of azobenzene-containing polymer membranes.
• Application of a novel solvent treatment to induce reversible changes in mesogen alignment.
• UV-vis irradiation to induce and observe photo-actuation behavior.
• Demonstration of a photo-driven membrane for liquid-phase applications.

Main Results:

• The solvent treatment effectively and reversibly changed the alignment of azobenzene mesogens within the polymer network.
• The treated membranes exhibited reversible photo-actuation under UV-vis irradiation.
• Successful demonstration of a photo-driven membrane capable of floating and sinking in a liquid medium.

Conclusions:

• A facile solvent treatment approach allows for reversible control over mesogen alignment, enhancing photo-actuation diversity.
• This method is significant for designing and fabricating novel azobenzene actuators for liquid-phase applications.
• The study opens new avenues for developing advanced soft robotic systems and responsive materials.