Fatigue-Resistant, Notch-Insensitive Zwitterionic Polymer Hydrogels with High Self-Healing Ability

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Achieving robust mechanical properties alongside self-healing capabilities in hydrogels remains a significant challenge.
• Zwitterionic polymers offer unique properties for advanced material development.
• Hydrogels are versatile materials with applications in various fields, but their longevity is often limited by mechanical failure.

Purpose of the Study:

• To synthesize and characterize novel zwitterionic polymer hydrogels with enhanced mechanical strength and self-healing properties.
• To investigate the role of ionic and hydrogen bonds in energy dissipation and network rebuilding.
• To explore the potential of these hydrogels in composite materials for advanced applications.

Main Methods:

• Random copolymerization of sulfobetaine methacrylate (SBMA), diallyldimethylammonium chloride (DAC), and 2-hydroxyethyl methacrylate (HEMA).
• Mechanical testing including fracture stress, fracture strain, and fracture energy measurements.
• Evaluation of self-healing efficiency at room temperature and assessment of fatigue resistance.
• Fabrication and testing of hydrogel/reduced graphene oxide (RGO) aerogel composites for conductivity and strain sensitivity.

Main Results:

• The synthesized zwitterionic hydrogels exhibited high mechanical strength (289-396 KPa fracture stress, 433-864% fracture strain) and fatigue resistance.
• The hydrogel with a 1:1 molar ratio of SBMA:DAC showed the highest self-healing efficiency (96.5% at room temperature for 10 hours) spontaneously.
• The materials demonstrated notch insensitivity with a fracture energy of 12000 J/m².
• Hydrogel/RGO composites displayed good strain sensitivity, reliability, and self-healing ability.

Conclusions:

• The developed zwitterionic polymer hydrogels effectively combine high mechanical strength with spontaneous self-healing properties.
• The interplay of ionic and hydrogen bonds is crucial for the observed energy dissipation and network recovery.
• These advanced hydrogels show promise for applications requiring durable and repairable materials, particularly in conductive composites.