Magnetite colloidal stability

Mori and Kawaguchi reported the preparation of magnetic polystyrene particles containing 30 wt% of magnetite. Magnetic polystyrene particles of 300 nm were produced and easily separated when persulphate, KPS or APS initiator was used. Conversely, due to high colloidal stability, the latex prepared by oil-soluble initiator (for instance AIBN) was not easy to separate, and the magnetite nanoparticles were located on the surface of the polystyrene latex. A mixture of initiators resulted in intermediate properties compared to individual systems [170]. 

Gomez-Lopera, S.A. Arias, J.L. Gallardo, V. Delgado, A.V. (2006), Colloidal stability of magnetite / poly (lactic add) core/ shell nanoparticles, Langmuir 22 2816-2821. 

If the nanometer particles consist of ferri or ferromagnetic nm-particles such as magnetite or iron, the prepared magnetic sols show — besides the high colloidal stability — a superparamagnetic behavior no hysteresis in the magnetization curve. 

The colloidal stability of 10 nm particles of magnetite dispersed in aqueous carriers can be calculated by superposition of the individual interparticle interaction energies including the Bom repulsion and the induced magnetic attraction. 

The deagglomeration model is well established for the repulsive force demonstrated as pressure P between two surfaces at a distance D, covered by grafted polymers with a chain length 5, the distance between the chains on the particle surface V, the Boltzmann constant kB, and the temperature T. Indeed, this theory can be applied for the deagglomeration and colloidal stability of magnetite particles in polymer solutions [15],... 

The magnetite particles so produced were stabilized by protective colloids such as gelatin for use in magnetic domain observations. These precipitated magnetite particles are used for production of magnetic fluids, as we describe later. 

Kinetics of Formation, Magnetic Moment, and Stability of Colloidal Magnetite... 

L. Vayssieres, C. Chaneac, E. Tronc, and J. P. JoUvet. Size tailoring of magnetite particles formed by aqueous precipitation An example of thermodynamic stability of nanometric oxide particles. J. Colloid Interface Sci., 205 205-212, 1998... 

Fig. 20 Examples of composite core-shell colloids without (a) and with (b) PMMA outer shell. The particle core consists of polymerized MPTMS-droplets stabilized by magnetite (a). Adapted from [147] with permission of Wiley-VCH...

The stable colloidal dispersion of iron oxide nanoparticles in a liquid carrier medium is known as magnetic ferrofluid. The iron oxides mostly used are magnetite Fe304 and maghemite y-Fe203. The carrier medium can be chosen to be aqueous or organic, depending on the application. The stability of the ferrolluids is the main... 

Modification of the magnetite surface with meso-2,3-dimercaptosuccinic acid (DMSA) is one of the variants to solve the problems of colloidal system stability in aqueous medium, the material biocompatibility, the immobilization of necessary compounds through thiol and carboxyl functional surface groups. 

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