Supercritical fluid mediated synthesis of poly(2-hydroxyethyl methacrylate)/Fe3O4 hybrid nanocomposite

► A magnetic polymer nanocomposite (Fe3O4-g-PHEMA) was successfully synthesized via in-situ dispersion polymerization in supercritical carbon dioxide. ► The Fe3O4 nanoparticles were well dispersed in the polymer matrix. ► The resulting nanocomposites have an excellent superparamagnetic property, which is favorable for their bio-applications. ► This new environmentally benign green synthetic route offers advantages of avoiding the use of organic solvents as well as easy separation of solvent.