Tough and stretchable ionogels by in situ phase separation

Area of Science:

• Materials Science
• Polymer Chemistry
• Electrochemistry

Background:

• Ionogels offer excellent ionic conductivity, stability, and non-volatility, making them suitable for technological devices.
• Existing ionogels often lack sufficient strength and toughness, limiting their practical applications.

Purpose of the Study:

• To develop a simple, one-step method for creating ultra-tough and stretchable ionogels.
• To investigate the in situ microstructure formation and its correlation with mechanical properties.

Main Methods:

• Random copolymerization of acrylamide and acrylic acid in an ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate).
• Utilizing monomers with distinct polymer solubilities to induce in situ phase separation.
• Characterization of mechanical properties, including fracture strength, energy, Young's modulus, and stretchability.

Main Results:

• Achieved ionogels with high fracture strength (12.6 MPa), fracture energy (~24 kJ m⁻²), and Young's modulus (46.5 MPa).
• Demonstrated high stretchability (~600% strain) with self-healing and shape-memory properties.
• In situ phase separation created a polymer-rich phase for energy dissipation and a solvent-rich phase for elasticity.

Conclusions:

• The one-step copolymerization method successfully produced ultra-tough and stretchable ionogels.
• The in situ phase separation is key to achieving enhanced mechanical properties and functionalities.
• This approach provides a versatile strategy for tuning ionogel properties for diverse applications.