Magnetically induced phase condensation in an aqueous dispersion of magnetic nanogels

Abstract

The applicability of aqueous magnetic colloids depends on their colloidal stability under the influence of various factors like external magnetic field and temperature. The magnetically induced phase condensation of magnetic colloids leads to the formation of spindle-like condensed phase drops of highly packed magnetic colloidal particles. The condensed phase drops are aligned parallel to the external magnetic field and may grow up to several microns thickness and tens or even hundreds of microns length. Thus, the magnetically induced phase condensation could be an advantage in magnetic separation applications, whereas in magnetic drug targeting applications it could lead to blood vessel clogging as well as to a significant decrease of the specific surface. We present the results of an experimental study regarding the influence of the external magnetic field and temperature on the magnetically induced phase condensation in an aqueous dispersion of pNIPA magnetic nanogels. A theoretical model was developed for the analysis of the data from forward light scattering experiments. It was found that the volume weight of the condensed phase increases with passing time, with increasing field intensity and temperature decrease. Using the proposed model, the magnetic field intensity dependence of the initial supersaturation of the sample was calculated.