Precipitation polymerization in acetonitrile and 1‐propanol mixture: synthesis of monodisperse poly(styrene‐co‐divinylbenzene) microspheres with clean and smooth surface

Precipitation polymerization of styrene (St)–divinylbenzene (DVB) has been carried out using acetonitrile/1‐propanol mixture as the reaction media and 2,2′‐azobisisobutyronitrile (AIBN) as initiator. Monodisperse micron‐sized poly(St‐co‐DVB) microspheres with clean and smooth surface were synthesized in the absence of any stabilizing agent such as surfactants or steric stabilizers. The effects of various polymerization parameters such as 1‐propanol fraction in the reaction media, initiator and total monomer concentration, DVB content, polymerization time and polymerization temperature on the morphology, particle size and size distribution were investigated. It was found that smoothly shaped stable particles were obtained when less than 70 vol% of 1‐propanol was used in the media. The particle size increased with the AIBN concentration, whereas the change of uniformity was less obvious. Monodisperse microspheres were obtained when the total monomers loading ranged from 0.5 to 3 vol%. The particle diameter ranged from 2.73 to 1.87 µm with an increasing DVB content and the uniformity was enhanced. In addition, the yield of microspheres increased with the increasing total monomer, initiator, and DVB concentration and polymerization time. Copyright © 2010 John Wiley & Sons, Ltd.