Mechanically Strong, Tough, and Shape Deformable Poly(acrylamide-co-vinylimidazole) Hydrogels Based on Cu²⁺...

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Robotics

Background:

• Shape-deformable hydrogels are crucial for soft actuators.
• Enhancing hydrogel mechanical strength and deformability is a key challenge.

Purpose of the Study:

• To develop mechanically robust and shape-deformable poly(acrylamide-co-vinylimidazole) [poly(AAm-co-VI)] hydrogels.
• To investigate the effect of Cu2+ complexation on hydrogel properties and shape deformability.

Main Methods:

• Photoinitiated copolymerization of acrylamide and vinylimidazole.
• Immersing poly(AAm-co-VI) in Cu2+ aqueous solution to form metal-chelate complexes.
• Characterization of mechanical properties (tensile strength, elastic modulus, toughness, fracture energy).
• Controlled application of Cu2+ solution to induce shape deformation.

Main Results:

• The Cu2+-complexed poly(AAm-co-VI) hydrogels exhibited significantly enhanced mechanical properties: tensile strength (7.7 MPa), elastic modulus (15.4 MPa), toughness (23.2 MJ m-3), and fracture energy (22.1 kJ m-2).
• Hydrogel strips demonstrated shape deformability (bending) upon Cu2+ coating.
• Precise control over 1D, 2D, and 3D shape deformation was achieved by tuning Cu2+ concentration, coating time, and region.

Conclusions:

• Cu2+ complexation is an effective strategy to simultaneously enhance hydrogel mechanical strength and introduce shape deformability.
• These mechanically strong, tough, and shape-deformable hydrogels are promising for developing advanced soft actuators.