Hydrophilic dual‐responsive magnetite/PMAA core/shell microspheres with high magnetic susceptibility and ph sensitivity via distillation‐precipitation polymerization

TLDR: In this article, a facile and effective approach to preparation of dual-responsive magnetic core/shell composite microspheres was reported, where the magnetite(Fe3O4)/poly(methacrylic acid) (PMAA) composite micro spheres were synthesized through encapsulat- ing c-methACryloxypropyltrimethoxysilane (MPS)-modified magnetite colloid nanocrystal clusters (MCNCs) with cross- linked PMAA shell.

Abstract: A facile and effective approach to preparation of dual-responsive magnetic core/shell composite microspheres is reported. The magnetite(Fe3O4)/poly(methacrylic acid) (PMAA) composite microspheres were synthesized through encapsulat- ing c-methacryloxypropyltrimethoxysilane (MPS)-modified magnetite colloid nanocrystal clusters (MCNCs) with cross- linked PMAA shell. First, the 200-nm-sized MCNCs were fabri- cated through solvothermal reaction, and then the MCNCs were modified with MPS to form active vinyl groups on the surface of MCNCs, and finally, a pH-responsive shell of PMAA was coated onto the surface of MCNCs by distillation-precipita- tion polymerization. The transmission electron microscopy (TEM) and vibrating sample magnetometer characterization showed that the obtained composite microspheres had well- defined core/shell structure and high saturation magnetization value (35 emu/g). The experimental results indicated that the thickness and degree of crosslinking of PMAA shell could be well-controlled. The pH-induced change in size exhibited by the core/shell microspheres reflected the PMAA shell contained large amount of carboxyl groups. The carboxyl groups and high saturation magnetization make these microspheres have a great potential in biomolecule separation and drug carriers. Moreover, we also demonstrated that other magnetic poly- meric microspheres, such as Fe3O4/PAA, Fe3O4/PAM, and Fe3O4/PNIPAM, could be synthesized by this approach. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 2725-2733, 2011