Formulation and Characterization of Ferrogels Based on Agar Gum and Octenyl Succinic Anhydride (OSA) Starch

Physicochemical and rheological analyses are carried out on ferrogels based on Agar gum in combination with octenyl succinic anhydride (OSA) starch in the presence of magnetic nanoparticles (MNPs) coated with a stabilizing agent (PNiPAAm). The objective of this work is to prepare nanocapsules of MNPs coated with OSA starch present in a rigid network of Agar to obtain a nanocomposite gel (ferrogel). It is found that the effect of MNPs on the properties of ferrogels has a direct relationship with PNiPAAm/OSA starch interactions. The results obtained show that the ferrogels have stable thermal properties and a high melting point (99.7 °C) for high concentrations of MNPs (0.1%). The rheological properties show that this concentration (0.1%) has a negative effect on the crosslinking of Agar, therefore a drop in viscosity. In addition, it is shown that each pore comprises three populations of MNPs (primary: 3–4 nm, secondary: 6–9 nm, and clusters: ≥12 nm). Moreover, it is found that MNPs are coated with OSA starch. In addition, the prepared materials possess at low concentration of MNPs an interesting stiffness and uniform surface morphology with a minimum of clusters leading to stable systems that can be used as biomaterials in nanomedecine.