Primary and secondary bonds in field induced aggregation of electric double layered magnetic particles.

Magnetic filaments able to survive on removal of the magnetic field have led to new applications in biotechnology and microfluidics. In this work, the stability of linear field induced aggregates composed of electric double layered magnetic particles has been studied in the framework of the DLVO theory. A suitable system of differential equations is proposed in order to determine how the percentage of bonds formed in a primary or a secondary energy minimum depends on the exposure time to the magnetic field. The theoretical predictions were compared with experimental data obtained by means of dynamic light scattering. The aggregation experiments were performed at different electrolyte concentrations and exposure times to the magnetic field. Fitting the experimental results according to the proposed theory allowed us to determine the rate at which bonds formed in a secondary energy minimum turn into stable bonds.