Polymerization of Olefin-Terminated Surfactant Bilayers on Magnetic Fluid Nanoparticles

Abstract

Magnetic fluids consisting of magnetite nanoparticles and a surrounding bilayer of a primary and a secondary fatty acid surfactant were prepared using either 10-undecenoic acid or undecanoic acid for one or both of the surrounding layers. The olefin units were included within the structure as sites for polymerizing the shell components and increasing the stability of the magnetic fluid. In our experiments, we exposed the magnetic fluids to various levels of γ irradiation and observed that the position of the unsaturated fatty acid in the bilayer affected their extent of polymerization, as evidenced by IR and NMR spectroscopies. When 10-undecenoic acid was used solely for the primary layer, γ irradiation resulted in only 50% conversion of the olefinic groups; however, their complete conversion occurred when 10-undecenoic acid was used as both the primary and secondary surfactants of the bilayer. Light scattering measurements showed that this latter magnetic fluid displayed a significant improvement in stab...