Synthesis of magnetic poly(styrene-methacrylic acid) spheres prepared by miniemulsion polymerization

R. Betancourt Galindo - O. S. Rodríguez Fernández - L. A. Garċía Cerda

Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna Hermosillo No. 140, C.P. 25253, Saltillo, Coahuila, México

Abstract
Magnetic poly(styrene-methacrylic acid), P(St-MAA), spheres were synthesized by miniemulsion polymerization in the presence of a ferrofluid. Magnetite (Fe₃O₄) nanoparticles obtained by the coprecipitation method, with an average diameter of 14 nm, were used as a magnetic source. A kerosene-based magnetite ferrofluid was mixed with styrene (St) and methacrylic acid (MAA) monomers in the presence of hexadecane as a co-surfactant; sodium dodecil sulphate (SDS) and potassium persulphate (KPS) were used as a surfactant and an initiator, respectively, for a subsequent polymerization. The morphology and properties of the magnetic spheres were studied by TGA, SEM and VSM. The magnetic P(St-MAA) spheres are uniform in shape and size and have diameters less than 150 nm. Magnetization data suggest a superparamagnetic behaviour and a maximum magnetization of 0.22 emu/g. Figs 7, Refs 11.