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 Gd³⁺ 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 Gd³⁺ 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 (AFM), 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 Gd³⁺ ion content in the particle. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1912–1918, 2004