Study On Preparation Of Functionalized Magnetic Polymer Microsphere And Morphology Manipulation

Functional magnetic polymer latex (MPL) , as a novel kind of material, enjoys both the properties of polymer material which can be modified or functionalized easily and magnetic material which can be controlled with the help of the external magnetic field. Thus, MPLs have found increasingly wide applications in the biomedical field, such as separation and purification of bio-molecules, probes for DNA/RNA hybridization and identification, targeted drug delivery, protein and nucleic acid detection, MRI contrast agent, and hyperthermia etc.While, in all these applications, where MPLs function as carriers or signal label for detection , the surface modification and morphology control of MPLs are as crucial as their monodisperse, high magnetite content properties to achieve better performance in the application procedures. Due to the clear importance of these properties, more and more researchers have shifted their interest from the preparation technology of the MPLs merely to the pursuit of surface modification and morphology control of MPLs, in order to achieve better performance in the application procedures and a get deeper insight of the relationships between the properties of MPLs and their interaction with bio-molecules. In this paper, we focused on the preparation of fuctionalized magnetic polymer microspheres and their morphology manipulation. And we divided our work into two parts. 1) We prepared the magnetic polymer latexes (MPLs) with epoxy-groups introduced via a modified mini-emulsion polymerization route as described. The epoxy-group content on the surface could be controlled by seed-emulsion followed and characterized by FTIR and Zeta Potential measurements. We also developed a novel approach to achieve manipulation of the morphology of the MPLs based on kinetic control of the polymerization system. MPLs with different morphologies were obtained ranging from core-shell micro-structures, dispersed micro-structures to asymmetric micro-structure which were characterized by TEM, DLS and TGA. The mechanisms of the contribution of kinetic factors such as polymerization rate, reaction time and temperature contributing to the forming of the different morphologies were also investigated.2) We also prepared the monodisperse superparamagnetic polymer latexes with high magnetite content by seed emulsion copolymerzation. In the system, 0.7-0.8μm Fe3O4 magnetic aggregation emulsion was severd as seeds and polymeric monomers of styrene and divinylbenzene were used as polymeric monomers to swell the seeds before the polymerization. The influence of the swelling time on the morphology and magnetic content of the composite microspheres was also investigated. The obtained microspheres were 0.7~1μm uniformed in size , superparamagnetic and with the magnetic content of 29 wt%~47 wt%, which were extensively characterized by transmission electron microscopy (TEM) , thermogravimetric analysis (TGA), fourier transform infrared spectrometer (FTIR) and vibrating sample magnetometer (VSM). After being functionalized with carboxyl group by a two-step seed emulsion, the superparamagnetic polymer latexes microspheres were applied into the bio-detection and got well performance.