Hydration Lubrication Mechanism of Light-Cured Polyethylene Glycol Diacrylate and 2-Acrylamido-2-methylpropanesulfonic Acid Hydrogels: Experimental and Molecular Dynamics Simulations

This study prepared a composite hydrogel using polyethylene glycol diacrylate (PEGDA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as raw materials, aiming to investigate the relationship between its hydration lubrication mechanism and friction behavior. By adjusting the mass fractions of PEGDA and AMPS, the hydrogel's mechanical properties were matched to those of articular cartilage, achieving a compressive modulus of 3.63 MPa. Friction tests revealed that the hydrogel exhibited a low coefficient of friction, consistently maintained within the range of 0.01-0.03 under various frequencies and load conditions, while demonstrating excellent lubrication stability throughout 7200 cycles of testing. Wetting and swelling tests demonstrate that AMPS effectively enhances the hydrogel's hydrophilicity while suppressing swelling, simultaneously increasing the bound water content within the system. Molecular dynamics simulations validate the excellent compatibility between PEGDA and AMPS. Constrained shear simulations reveal the hydrated lubrication layer's crucial role in mitigating shear stress, dispersing heat dissipation, and maintaining lubrication stability.