Programming Homogeneous Hydrogels Using Directional Ion Transport toward Rapid 3D Reconfiguration.

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Robotics

Background:

• Environmentally adaptive hydrogels reconfigure under stimuli, useful for sensing and robotics.
• Achieving programmable 3D morphing in homogeneous hydrogels with constant stimuli is challenging.

Purpose of the Study:

• Develop supramolecular poly(amic acid) salt (PAAS) hydrogels capable of predictable 3D structure formation.
• Utilize directional ion transport inspired by starfish for programmable shape-morphing.

Main Methods:

• Synthesized PAAS hydrogels via aqueous polymerization of s-BPDA and PDA with imidazole-based bases.
• Applied thermal treatment at 50 °C to form hydrogels with high-density carboxylates.
• Induced 3D shape-morphing using seawater stimulation for asymmetric cross-linking and swelling/contraction.

Main Results:

• Achieved programmable 3D shape-morphing in homogeneous hydrogels using a single stimulus (seawater).
• Demonstrated dynamic supramolecular networks enabling reconfigurability and reconstruction of complex 3D architectures.
• Exhibited exceptional stability with low swelling ratios (<50%), high tensile strength (up to 2.1 MPa), and rapid 180° deformations (within 70 s).

Conclusions:

• Successfully programmed 3D morphologies of homogeneous hydrogels using directional ion transport.
• Highlighted the potential of these PAAS hydrogels for advancing shape-morphing engineering in soft robotics and intelligent sensing.
• Showcased the reconfigurable nature and stability of the developed hydrogels for advanced material applications.