As a microreactor

hollow microspheres could be used to load magnetic nanoparticles.Asymmetric hollow polymeric microspheres with micropores of 14.9 nm

alkyl bromine groups on exterior wall and carboxyl groups on interior wall were produced through three steps: (a) synthesis of the coreshell microparticles with copolymer of maleic anhydride (MAn) and divinyl benzene (DVB) as the shell

and copolymer of maleic anhydride (MAn) and vinylacetate (VAc) as the core; (b) surface bromizing of the coreshell microparticles by reaction with dibromoethane; (c) etching of the cores with acetone

and followed by the hydrolyzing of the anhydride groups on interior wall.Fe3O4 magnetic nanoparticles were loaded into the cavity of prepared hollow polymeric microspheres by two steps: first

Fe2+ and Fe3+ were infiltrated into the hollow microspheres and selective adsorbed on the interior wall under the effect of carboxyl groups; secondly

in appropriate condition

coprecipitation were carried out to obtain Fe3O4 magnetic nanoparticles.In addition

influences of parameters relating to the above mentioned reaction

such as the mole ratio of Fe2+ and Fe3+

reaction temperature and reaction time

on the saturation magnetization of the magnetic microspheres were investigated.The results show that

the optimum reaction conditions to the balance of loading selectivity and value of saturation magnetization were as follow: molar ratio of Fe2+ and Fe3+ was 2/3

reaction temperature was 80℃ and reaction time was 1.5 h

for obtained the best value of saturation magnetization 12.34 emu/g.