Preparation and Characterization of Monodisperse Magnetic Carbon Microspheres with Controllable Shell Thickness and High Water Solubility

Core-shell magnetic carbon microspheres with good monodispersity and uniformity were obtained. Good monodispersity was achieved by adding a dispersant in the solvothermal synthesis of magnetic core, as the criterion for good dispersibility was set up through dynamic light scattering (DLS). The excellent dispersing agent (Poly (4-styrenesulfonic acid-co-maleic acid, SS: MA = 3:1) sodium salt, PSSMA) has been selected among three dispersants, which greatly improves the dispersibility of the magnetic core in the coating environment, thereby obtaining a core-shell structure with uniform coating and monodispersity. Carbon shell was gained by deposit coating process of resorcinol formaldehyde resin (RF) onto the magnetic core and then subsequent carbonization under N atmosphere. At the same time, the carbon shell thickness can be adjusted up to 70 nm by adjusting the RF shell thickness which is tunable ranging from 30 to120 nm.