Flower‐Like SiO2‐Coated Polymer/Fe3O4 Composite Microspheres of Super‐Paramagnetic Properties: Preparation via A Polymeric Microgel Template Method

Abstract

N‐isopropylacrylamide (NIPAM) and acrylic acid (AA) copolymer microgels P(NIPAM ‐co‐AA) with different amount of AA were prepared by using a reverse suspension polymerization technique. The polymeric microgels were used firstly as micro‐containers to include Fe3O4 nanoparticles and then as micro‐reactors to control the hydrolysis of tetraethyl orthosilicate (TEOS). In this way, various super‐paramagnetic composite microspheres (P(NIPAM‐AA)/Fe3O4/SiO2) with different morphologies were prepared. It was demonstrated that the morphologies of the composite microspheres could be tailored to a certain extent by either varying the ratio of the two monomer units in the template microgels or the amount of SiO2 deposited. The sensitivity of the composite microspheres to an external magnetic field was determined by the amount of Fe3O4 included. The magnetic responsibility of the composite microspheres, and the ease of modifying the surfaces may make the microspheres of important use in the mild separation of bioactive materials, loading of active materials, and radiation and shock absorption, etc.