PEG macromonomer having one methacryloyl end group for per polymer chain was selected as reaction stabilizer. The distribution of molecular weight of the macromonomer was less than 1.1 based on the GPC analysis. Poly(acrylonitrile/styrene) particles with sub-micron sizes were prepared by dispersion copolymerization of acrylonitrile with styrene by using 2,2-azobisisobutyronitrile(AIBN) as a free radical initiator in the presence of PEG macromonomer in V(ethanol)∶V(water)=7∶3 mixed solvents at 60 ℃ for 24 h. The particles having narrow size-distribution were obtained and studied by transmission electron microscopy(TEM) and laser light scattering(LLS). The surfaces of the particles have unusual structures(strawberry form or wheel form shows) which can be control by changing molecular weight of PEG macromonomer and other reaction conditions. The structure of the freeze-dried particles was investigated by X-ray diffraction(XRD) system and showed a distinct diffraction peak at 2θ=22.6°, indicating that the particles are crystallized.
