Unveiling the Compression Mechanical Properties of AMPS-APTAC-DMAAm Terpolymeric Hydrogels

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomedical Engineering

Background:

• Polyampholyte hydrogels show potential for load-bearing biomedical uses.
• Understanding the relationship between hydrogel composition and mechanical properties is crucial for optimizing their performance.

Purpose of the Study:

• To investigate the influence of initial monomer concentration and a neutral comonomer (DMAAm) on the swelling and mechanical behavior of AMPS-APTAC hydrogel networks.
• To determine how varying monomer concentration, crosslinker density, and DMAAm fraction impacts hydrogel stiffness, strength, and toughness.

Main Methods:

• Terpolymeric AMPS-APTAC-DMAAm hydrogels were synthesized with varying monomer concentrations (1-2 M), crosslinker (MBAAm) levels (1-5 mol%), and DMAAm fractions (0-0.16).
• Swelling in water and unconfined compression tests were performed to evaluate mechanical properties, including Young's modulus, fracture stress, fracture strain, and toughness.

Main Results:

• Increased monomer concentration led to denser networks, reduced swelling, and enhanced stiffness.
• The inclusion of DMAAm significantly improved gel strength and toughness through reversible associative interactions.
• Specific compositions demonstrated high performance: C2M1 hydrogel had E=35.4 kPa, σf=0.8 MPa, εf=82%, W=65.6 kJ·m⁻³; gels with DMAAm (z=0.06) reached σf=4.28 MPa and W=196.0 kJ·m⁻³; (z=0.16) showed E=103.0 kPa, σf=2.34 MPa, W=191.6 kJ·m⁻³.

Conclusions:

• Initial monomer concentration and DMAAm-mediated associations are independent design parameters for tuning AMPS-APTAC polyampholyte hydrogels.
• These findings provide a basis for optimizing hydrogel properties for specific load-bearing biomedical applications.