Ultra-Robust Conductive Hydrogels Enabled by a Gradient Bond-Breaking Pseudo-Drying Strategy.

Area of Science:

• Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Hydrogels are hydrophilic polymer networks with significant biomedical potential.
• Conventional hydrogels face limitations in achieving high strength, modulus, toughness, and fracture resistance.
• Dehydration and low-temperature crystallization further restrict hydrogel applications.

Purpose of the Study:

• To address the limitations of conventional hydrogels by developing a biomimetic gradient bond-breaking strategy.
• To create hydrogels with enhanced mechanical properties, including high strength, modulus, and toughness.
• To explore the potential of these advanced hydrogels in flexible electronics and biosensors.

Main Methods:

• Constructed hydrogels with covalently crosslinked hierarchical reinforcing phases: crystalline domains and aramid nanofibers (ANFs) networks.
• Incorporated a biomimetic gradient bond-breaking mechanism within the aqueous-poor phase.
• Fabricated hydrogels with tunable mechanical properties via controlled fabrication parameters.

Main Results:

• Achieved a modulus of 12.4 MPa, toughness of 73.66 MJ m^-3, and fracture toughness of 268.8 kJ m^-2 at 70% water content.
• Demonstrated fracture-resistant properties comparable to dry-state materials.
• Exhibited broad-temperature stability, high conductivity, and cytocompatibility.

Conclusions:

• The biomimetic gradient bond-breaking strategy successfully enhances hydrogel mechanical properties.
• The developed hydrogels surpass existing PVA-based hydrogels and natural structural materials in performance.
• A low-temperature-operable strain sensor was successfully developed, showcasing the material's practical applications in flexible electronics.