High strain-rate response of injectable PAA hydrogel

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Mechanical Engineering

Background:

• Injectable hydrogels show promise for soft tissue replacement due to biocompatibility and tunable properties.
• Applications include osteoarthritis and degenerative disc disease treatment, requiring mechanical resilience under dynamic loading.
• Limited data exists on the dynamic mechanical behavior of injectable hydrogels under impact conditions.

Purpose of the Study:

• To characterize the dynamic mechanical properties of polyacrylic acid (PAA) hydrogels under high strain rates.
• To evaluate the influence of acrylic acid concentration and swelling conditions on hydrogel dynamic response.
• To provide essential data for the design of hydrogels subjected to dynamic loading.

Main Methods:

• Preparation of injectable PAA hydrogels with varying acrylic acid concentrations (3.37%, 6.75%, 13.5%).
• Testing of hydrogel specimens in raw, phosphate-buffered saline (PBS) swollen, and PBS swollen at 37°C conditions.
• Utilizing the split Hopkinson pressure bar technique to determine dynamic responses at strain rates from 100 to 2590 s⁻¹.

Main Results:

• Dynamic bulk moduli ranged from 1.55 to 47.8 MPa.
• Results demonstrated significant dependence of dynamic modulus on acrylic acid concentration.
• Swelling conditions and elevated temperature influenced the hydrogel's dynamic mechanical performance.

Conclusions:

• PAA hydrogels exhibit a wide range of dynamic bulk moduli under high strain rates.
• Mechanical properties are significantly influenced by material composition and environmental conditions.
• This study provides critical insights into the dynamic behavior of injectable hydrogels for soft tissue engineering applications.