Microparticles of Poly(methacrylic acid)-Gadolinium Ion Complex and Their Magnetic Force Microscopic Images

Modified poly(methacrylic acid) microparticles complexed with gadolinium(III) (Gd³⁺) ions were prepared in 100 nm. The emulsion terpolymerization of methacrylic acid, ethyl acrylate, and allyl methacrylate and the following complexation with Gd⁸⁺ ions yielded the polymer particles with different Gd³⁺ ion contents. Potentiometric titration of the complexation of the particle with Gd³⁺ ions indicated the formation of a very stable tris-carboxylate coordinate complex with the Gd ³⁺ ion. Electron spin resonance and IR spectra of the complexed particles were dependent on the Gd³⁺ ion content and the coordination environment in each particle. The microparticles dispersed on a mica substrate were subjected to atomic force microscopy (ATM), followed by magnetic force microscopy (MFM). AFM showed 100-nm-sized and monodispersed spherical images. The following MFM clearly provided strong magnetic responses exactly on the same particle positions, of which the images were also dependent on the Gd ³⁺ ion content in the particle. 2004 Wiley Periodicals, Inc.