Preparation and Characterization of Composite Microspheres with Magnetic and Temperature Dual Stimuli-responsive Properties

Oleic acid-coated Fe3O4 nanoparticles were synthesized by partial reduction coprecipitation method. Magnetic and temperature dual responsive composite microspheres, consisting of superparamagnetic Fe3O4 nanopaticles and thermoresponsive poly(N-isopropylacrylamide-acrylamide) microgel, were prepared by emulsion-free copolymerization. TEM, FTIR and XRD measurements were performed to characterize the structure and morphology of the composite microspheres, vibrating sample magnetometry(VSM) and the dynamic light scattering(DLS) were carried out to characterize the magnetic properties and thermoresponsive properties of the microspheres, respectively. The results show that the resulting composite microspheres possessed a core-shell structure, and the average particle size was 100 nm. Furthermore, it was confirmed that the composite microspheres exhibited magnetic and temperature dual stimuli-responsive properties. The lower critical solution temperature(LCST) of the composite microspheres is about 40 degrees C in water.