Tunable Sponge-Like Hierarchically Porous Hydrogels with Simultaneously Enhanced Diffusivity and Mechanical...

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Matter Physics

Background:

• Crosslinked polymers and gels are vital for applications like soft robotics, energy storage, and drug delivery.
• Their performance is often limited by slow diffusion and a trade-off between mechanical properties and swelling behavior.
• Existing methods to improve diffusion in hydrogels often compromise their mechanical integrity.

Purpose of the Study:

• To develop a universal method to overcome the swelling-mechanical property trade-off in hydrogels.
• To enhance mass transport and volume-changing abilities for practical applications.
• To demonstrate a novel approach for fabricating high-performance hydrogels.

Main Methods:

• Utilized cononsolvency photopolymerization to synthesize hydrogels.
• Investigated poly(N-isopropylacrylamide) as an exemplary system.
• Extended the technique to other polymer systems like poly(N-tertbutylacrylamide-co-polyacrylamide) and polyacrylamide.

Main Results:

• Achieved a unique open porous network with continuous microchannels in hydrogels.
• Demonstrated record-high volumetric (de)swelling speeds, significantly faster than conventional hydrogels.
• Observed simultaneous improvements in Young's modulus and toughness compared to hydrogels made in pure solvents.
• Validated cononsolvency as a generic phenomenon driven by competitive adsorption.

Conclusions:

• Cononsolvency photopolymerization offers a universal approach to enhance hydrogel performance.
• The developed hydrogels exhibit superior swelling kinetics and mechanical properties.
• This advancement enables new possibilities for hydrogel applications, including in-air operation and 3D printing.