Preparation of monodisperse polystyrene spheres in aqueous alcohol system

The aqueous methanol/ethanol/n-propyl systems have been exploited as dispersion medium in emulsion polymerizing of polystyrene (PS) using sodium lauryl sulfate and potassium persulfate as emulsifier and initiator, respectively. The diameter of PS spheres synthesized in aqueous methanol/ethanol/n-propyl dispersion media is 80 nm–1.15 Am/150 nm–1.3 Am/260 nm–1.65 Am. The replacement of water dispersion medium with alcohol dispersion medium can lift the upper limit of PS spheres size from 1 to 1.65 Am. A seeded growth technique based on aqueous alcohol dispersion media was developed to improve spheric-shape and monodispersity as well as increasing PS spheres size. In this technique, the styrene added for the growth of seeds is diluted with four times volume absolute alcohol, which makes the swelling process of styrene in seed (which is necessary in the conventional two-step seed growth technique) unnecessary and consequently reduces dramatically the synthesis time. D 2003 Elsevier Science B.V. All rights reserved.