Monodispersed polystyrene (PS) microspheres were synthesized by the precipitation polymerization of styrene in low toxic ethanol/water mixed solvent using K2S2O8/NaHSO3 as initiators at 25 ℃.This work aimed at providing a new method of low-temperature preparation of monodispersed PS microspheres without cross-linker.Several reaction conditions

including reaction times

weight contents of initiators

and volume ratios of ethanol and water

were investigated in order to determine the effects of polymerization process on PS microspheres.The monomer conversion

and the size and yield of PS microspheres increased with reaction time and kept constantly after 12 h.With the increase of initiator content

the monomer conversion

and the size and yield of PS microspheres were increased

but the size distribution was nonuniform.When the weight contents of initiators K2S2O8and NaHSO3

relative to that of styrene

were no more than 2.0% and 1.3%

respectively

PS microspheres were monodispersed.When the volume content of water in ethanol/water mixed solvent changed from 10% to 40%

the monomer conversion

and the yield of PS microspheres were increased

and monodispersed PS microspheres can be obtained.However

when the volume content of water was more than 40%

these performances would be decreased with wide microsphere distribution.When the stirring speed was changed from 600 r/min to 1200 r/min

PS microspheres had a little difference in size

yield and monomer conversion.The formation mechanism of PS microspheres was studied.