The Effect of Coated- ${\rm Fe}_{3}{\rm O}_{4}$ Nanoparticles on Magnetic Properties of Ferrogels Produced by Diffusion Route

In this paper, we report a novel, nontoxic and environmentally friendly diffusion route to obtain superparamagnetic poly(vinyl alcohol) (PVA)/polyacrylic acid (PAA) coated- Fe₃O₄ ferrogels (D-PAA). Magnetic properties of these D-PAA ferrogels were compared with regular ones produced with noncoated magnetite nanoparticles (D-NC). Their morphological features were studied by SEM-FEG. Absorption tests were performed in order to assess diffusion of nanoparticles into the PVA-polymeric matrix. D-PAA samples exhibit better dispersion of the nanoparticles within polymeric matrix in comparison with D-NC samples. The effective diffusion coefficients (D_eff) obtained, as well as the nature of the functional groups in question, suggests interactions between the PAA and PVA in D-PAA samples. In D-NC samples is presumed that the iron atoms in the surface of the nanoparticles act as Lewis acids and coordinates with molecules that donate lone-pair electrons. The results suggest a reduction in the magnetic interaction for the coated nanoparticles case, due to the improvement of the dispersion of the nanoparticles into the polymeric matrix.