The synthesis and rheological characteristics of colloidal systems containing functional magnetic nanoparticles

Functional magnetic nanoparticles were synthesized by homogeneous nucleation from the solution of metal salts in the presence of functional oligoperoxide surfactants (FOS). FOS addition causes the decrease of the quantity of large particles and agglomerates. The presence of radical forming sites on the magnetic colloid surface provides the possibility of carrying out of grafted polymerization in a wide temperature range in the media of various polarities. As a result of homogeneous nucleation of the particles in the presence of oligomer surfactants the extremes of the particle size, dynamic viscosity and maximal value of FOS sorption are observed at the same FOS concentration in the solution. The dependences of dynamic viscosity of magnetic colloid suspensions modified by various amount of FOS on shear stress witness the formation of multi-layer functional shell with different orientation of polar functional groups and their different remoteness from the surface. The formation of new polymeric chains tethered to the colloid surface leads to breaking particle assemblies and provides both the aggregative and sedimentation stabilization of the magnetic fluids formed and targeted affinity to biological substrates. (c) 2004 Elsevier B.V. All rights reserved.