Synthesis and characterization of PVA ferrogels obtained through a one-pot freezing�Cthawing procedure

Polyvinyl alcohol (PVA) ferrogels were easily obtained through a one-pot technique that involves co-precipitation of iron salts in the presence of a PVA solution, followed by freezing?Cthawing cycles of the resulting nanoparticles (NPs) dispersions. The protecting effect of PVA enabled the synthesis of small magnetic NPs that did not agglomerate in the initial solution allowing the synthesis of well-dispersed ferrogels by physical cross-linking. Physical properties of the physically cross-linked ferrogels, as swelling ability, melting temperature, and crystallinity, were barely affected by the presence of NPs, presenting similar or improved values when compared with chemically cross-linked systems. Ferrogels showed superparamagnetic properties at room temperature that combined with the absence of toxic residues arising from cross-linking agents make them ideal candidates for their use in biomedical applications (artificial muscles, drug delivery, and sensors among others).