Hydrophilic magnetic polymer latexes. 2. Encapsulation of adsorbed iron oxide nanoparticles

The encapsulation of seed polymer particles coated by anionic iron oxide na noparticles has been investigated using N-isopropylacrylamide as a main mon omer, N,N-methylene bisacrylamide as a crosslinking agent, itaconic acid as a functional monomer and potassium persulfate as an anionic initiator. The magnetic latexes obtained have been characterized with regard to particle size, iron oxide content and electrophoretic mobility. All these properties have been examined by varying several polymerization parameters: reaction medium, monomer(s) and crosslinking agent concentrations, nature of seed la texes and type of polymerization (batch versus shot process). The magnetic content in the polymer microspheres strongly depends on the polymerization procedure (i.e., encapsulation process) and varies between 6 and 23 wt%, an d monodisperse magnetic polymer particles were obtained.