Magnetic studies of iron oxide nanoparticles coated with oleic acid and Pluronic® block copolymer -: art. no. 10Q905

We have prepared and studied iron-oxide nanoparticles coated with oleic acid (OA) and Pluronic (R) polymer. The mean diameter of the iron-oxide nanoparticles was 9.3(+/-)0.8 nm. Saturation magnetization values measured at 10 K varied from 66.1(+/- 0.7) emu/g to 98.7(+/- 0.5) emu/g. At 300 K the loops showed negligible coercive field. The peaks in zero-field-cooled susceptibility decreased from 280 to 168 K with increasing OA concentration up to 10.6 wt %, and remained nearly constant for higher concentrations. This suggests that incomplete coverage of the OA allows small, interacting agglomerates to form. (c) 2005 American Institute of Physics.