Ferrite Synthesis In Microstructured Media: Template Effects And Magnetic Properties

Inverse micelles and organogels provide novel environments to synthesize ferrite particles. The fluid microstructure provides a template for the synthesis. Our experiments with ferrite synthesis in inverse micelles indicate the formation of superparamagnetic nanoparticles. Of interest is the encapsulation of these particles in polymer microspheres. The encapsulation is done using simple polymer precipitation in the micellar nonsolvent. The process results in a polymer-ferrite composite exhibiting supermagnetism. Low temperature spin glass properties of the composite are characterized through SQUID measurements. These composites have a superparamagnetic blocking temperature of 16 K and follow Curie-Weiss law at temperatures above 60 K with the fitted parameters: C = 0.941 emu/g K, theta=-287 K, and TIP=0.0001 emu/g. Since the polymer used is polyphenol, a highly functionalizable material, the composite is well suited for applications in magnetic bioseparations and magnetic coatings. (C) 1997 American Institute of Physics.