Anion-Induced Reversible Actuation of Squaramide-Crosslinked Polymer Gels

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polymer networks can be designed for specific responses.
• Supramolecular interactions offer tunable control over material properties.

Purpose of the Study:

• To investigate supramolecular anion binding to squaramide crosslinkers in poly(N,N-dimethylacrylamide) gels.
• To explore the resulting swelling behavior and chemically driven actuation.

Main Methods:

• Synthesis of poly(N,N-dimethylacrylamide) gel networks with squaramide crosslinkers.
• Volume swelling ratio measurements.
• Proton Nuclear Magnetic Resonance (¹H NMR) and UV-Vis titrations.
• Fabrication of soft actuators from rod-shaped gels.

Main Results:

• Gel swelling is dependent on anion type and concentration.
• Anion binding affinity correlates with swelling behavior.
• Reversible bending actuation was achieved in response to anion concentration changes.
• Actuation was accompanied by a distinct green coloration.

Conclusions:

• Supramolecular anion binding is an effective strategy to control polymer gel swelling and induce actuation.
• This work presents a novel approach for creating chemically responsive soft actuators.
• The findings open new avenues for designing advanced functional materials.