Synthesis and characterization of Fe3O4/PPy/P(MAA-co-AAm) trilayered composite microspheres with electric, magnetic and pH response characteristics

The synthesis of functionalized electromagnetic polymer microspheres with a trilayer core-shell structure has been successfully achieved by a process involving (1) preparation of superparamagnetic Fe3O4 nanoparticles through a co-precipitation approach; (2) coating of polypyrrole (PPy) on the surface of Fe3O4 nanoparticles in the presence of pyrrole and FeCl3 via a common ion effect; and (3) fabrication of poly(methacrylic acid-co-acrylamide), P(MAA-co-AAm), on the basis of Fe3O4/PPy electromagnetic cores by a miniemulsion polymerization route. The morphological and structural investigations by different characterization techniques prove that the microspheres show well-shaped spheres and good thermal stability, and there exists certain interaction among Fe3O4, PPy and P(MAA-co-AAm) chains. The examinations of the magnetic properties conducted by a vibrating sample magnetometer indicate that the electromagnetism microspheres are superparamagnetic. The saturation magnetization of Fe3O4/PPy nanocomposites is increased from 27.9 to 32.52 emu g(-1) with increasing the Fe3O4 content, and Fe3O4/PPy/P(MAA-co-AAm) composite microspheres hold the minimal saturation magnetization of 5.27 emu g(-1). The electrical conductivities of these microspheres range from 10(-9) to 10(-3)S cm(-1) depending on the compositional proportion of the PPy conducting polymer. The core-shell trilayer electromagnetic polymer microsphere displays controllable electrical and magnetic properties, as well as pH response, and is expected to have specific drug targeted delivery and separation applications. (C) 2009 Elsevier B.V. All rights reserved.