Synthesis and comprehensive rheological investigation of gum acacia-grafted-poly(N,N-dimethylacrylamide) hydrogel incorporated with CoFe2O4 nanofillers

Abstract The advancement of nanocomposite hydrogels with superior mechanical robustness, tunable swelling, and rheological performance is pivotal for next-generation biomedical and industrial systems. In this work, a novel gum acacia-grafted poly(N,N-dimethylacrylamide) (GA-g-PDMAAm) hydrogel reinforced with cobalt ferrite (CF/CoFe₂O₄) nanofillers was synthesized via free-radical graft copolymerization. CoFe₂O₄ nanoparticles (average crystallite size: 8.32 nm, calcined) were fabricated through chemical co-precipitation and homogeneously embedded into the hydrogel network, imparting enhanced structural integrity, magnetic responsiveness, and thermal stability. FTIR, XRD, FE-SEM, and TGA analyses confirmed efficient grafting, crystalline dispersion, and improved thermal resistance, with weight loss at 450 °C reduced from 72.24 to 59.58% and an onset degradation temperature near 150 °C. Rheological studies revealed shear-thinning pseudoplasticity, storage modulus (G′) dominance over loss modulus (G″) across 0.1–100 rad s⁻ 1 , and damping factors (tan δ) below 0.3, indicating elastic-dominated behavior. Thermal sweeps showed modulus stability up to 35 °C, particularly in high CoFe₂O₄-loaded networks. Mechanical testing identified GADMACF-10 as exhibiting maximal shear stress under 25% strain, while swelling capacity increased from 9.78 g g⁻ 1 to 13.85 g g⁻ 1 (~ 41.6% enhancement) at optimal filler loading (GADMACF-50). These findings position GA-g-PDMAAm/CoFe₂O₄ nanocomposites as multifunctional, mechanically resilient, and highly absorbent materials suited for wound healing, drug delivery, and tissue engineering applications.