Synthesis and morphology of an iron oxide/polystyrene/poly(isopropy acrylamide-co-methacrylic acid) thermosensitive magnetic composite latex with potassium persulfate as the initiator

In this work, an iron oxide (Fe3O4)/polystyrene (PS)/poly(N-isopropylacryl amide-co-methacrylic acid) [P(NIPAAM-MAA)] thermosensitive magnetic composite latex was synthesized by the method of two-stage emulsion polymerization. The Fe3O4 Particles were prepared by a traditional coprecipitation method and then surface-treated with either a PAA oligomer or lauric acid to form a stable ferrofluid. The first stage for the synthesis of the thermosensitive magnetic composite latex was to synthesize PS in the presence of a ferrofluid. by emulsion polymerization to form Fe3O4/PS composite latex particles. Following the first stage of reaction, the second stage of polymerization was carried out with N-isopropylacryl amide and methacrylic acid as monomers and with Fe3O4/PS latex as seeds. The Fe3O4/PS/[P(NIPAAM-MAA)] thermosensitive magnetic particles were thus obtained. The effects of the ferrofluids on the reaction kinetics, morphology, and particle size of the latex were discussed. A reaction mechanism was proposed in accordance with the morphology observation of the latex particles. The thermosensitive property of the thermosensitive magnetic composite latex was also studied. (c) 2007 Wiley Periodicals, Inc.