Synthesis, rheological and thermal studies of Gum ghatti-cl-poly(acrylic acid) hydrogels containing CoFe2O4 nanoparticles

Abstract

In this work, Gum ghatti-cl-poly(acrylic acid)/CoFe₂O₄ (GGAACF) hydrogels were synthesized using a free radical polymerization technique, with CoFe₂O₄ nanoparticles incorporated via a co-precipitation method using nitrates as precursors. Thermal gravimetric analysis (TGA) revealed that the inclusion of CoFe₂O₄ nanoparticles enhanced the thermal stability of the hydrogels. Swelling studies indicated that the addition of 30 mg of CoFe₂O₄ nanoparticles maximized water retention. Rheological assessments demonstrated non-Newtonian behavior, with flow curves fitted best by the Power Law model. The incorporation of CoFe₂O₄ nanoparticles significantly improved the hydrogel’s elasticity and viscosity, as evidenced by a higher storage modulus (G′) compared to the loss modulus (G″) across all frequencies, indicating the elastic nature of the hydrogels. The decrease in complex viscosity with increasing frequency confirmed the pseudoplastic properties of the hydrogels, attributed to the random alignment of CoFe₂O₄ nanoparticles within the matrix. Tan δ values were below unity at all tested frequencies, underscoring the hydrogels’ strong elastic properties. These findings highlight the effectiveness of rheological analysis in characterizing the viscoelastic behavior of polymer hydrogels, which can be tailored for various applications.