Facile synthesis of poly(acrylonitrile-co-styrene) microspheres depending on the self-stabilized precipitation polymerization

Polyacrylonitrile (PAN) microspheres are widely used in various fields due to their excellent chemical stability, mechanical strength and tunable structure. In this paper, poly(AN-co-St) microspheres were prepared by self-stabilized precipitation (2SP) polymerization due to its good controllability and easy operability. Due to the significant influence of the solvent on precipitation polymerization, ethyl acetate was selected as the solvent resulting in the good sphericity and size controllability of poly(AN-co-St) microspheres. When the solubility parameter of the solvent system was altered, the morphology of the poly(AN-co-St) microspheres changed from a spherical shape to a floral pattern. The average particle size of these poly(AN-co-St) microspheres could be easily controlled within the range of 0.4–1.0 µm. In addition, the 2SP polymerization attained a maximum yield of 97% at a monomer concentration of 25 wt%. Moreover, because of no addition of the stabilizer in the process of the 2SP polymerization, the poly(AN-co-St) microspheres are much clear. The effect of initiator concentration and crosslinker concentration on poly (AN-co-St) microspheres were also investigated. The benefits of employing the 2SP polymerization technique include excellent sphericity and homogeneity of the microspheres, high production efficiency, the ability to control particle size and straightforward operational procedures, which make the 2SP polymerization highly promising for synthesizing PAN microspheres.