Hydrothermal Conditioning of Physical Hydrogels Prepared from a Midblock-Sulfonated Multiblock Copolymer

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Nanostructured amphiphilic macromolecules are crucial for ion and water transport in energy and environmental technologies.
• Thermoplastic elastomers form stable hydrogel networks upon self-assembly in polar liquids.

Purpose of the Study:

• Investigate swelling kinetics and temperature-dependent water uptake in midblock-sulfonated thermoplastic elastomers.
• Correlate nanostructural changes with macroscopic swelling to understand structure-property relationships.

Main Methods:

• Synchrotron small-angle X-ray scattering (SAXS) for real-time water sorption kinetics.
• Gravimetric measurements to determine swelling capacity.
• Analysis of copolymer films prepared with different casting solvents.

Main Results:

• Real-time water-sorption kinetics were elucidated, correlating nanostructure evolution with swelling.
• An unexpected transition in equilibrium swelling capacity was observed around 50 °C.
• Hydrothermal conditioning above this transition enabled retained superabsorbent swelling at ambient temperature.

Conclusions:

• Fundamental structure-property behavior was established for sulfonated thermoplastic elastomers.
• The discovered thermal transition offers a method to control and retain superabsorbent properties.
• These findings are significant for advanced energy and environmental applications.