Responsive P(NIPAM-co-AA) Particle-Functionalized Magnetic Microspheres

Functionalized magnetic microspheres were prepared by anchoring cross-linked core–shell poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AA)) nanoparticles onto silica-coated magnetic microspheres (Fe3O4@SiO2). First, the smaller polystyrene/P(NIPAM-co-AA) core–shell nanoparticles were synthesized through seed emulsion polymerization and adhered to the surface of amino-modified Fe3O4@SiO2 micorspheres, which were made using the modified Stöber method through electrostatic interaction under appropriate preparation conditions. An amidation reaction between the carboxylic and amino groups on the respective surfaces was then catalyzed. Finally, the novel architecture magnetic microspheres with multiresponsive functionalities were obtained, and their polymerization conditions, environmental sensitivity, and magnetic properties were discussed and optimized. The superparamagnetism and temperature/pH dual responsivity and excellent dispersibility of the P(NIPAM-co-AA) functionalized magnetic microspheres provide them with high potential to be used in the fields of controlled drug delivery, bioseparation, and catalysis.