ScienceAsia 24 (1998): 169-192 |doi: 10.2306/scienceasia1513-1874.1998.24.169

SYNTHESES OF SUPER-FINE MONO-DISPERSED PARTICLES OF POLY(STYRENE-CO-METHYL METHACRYLATE) BY DISPERSION COPOLYMERIZATION

SUDA KIATKAMJORNWONG^a,* AND ARUNSRI ANANTAPHIPHAT^b

ABSTRACT: Poly(styrene-CO-methylmethacrylate) particles with a spherical shape, smooth surface, and a size range of 0.3-1.5 m with a narrow size distribution were obtained by dispersion copolymerization in ethanol/water media with azo-bisisobutyronitrile initiator and a polymeric dispersant of poly(N-vinylpyrrolidone). Without the dispersant, the copolymers were formed in sheets and lumps. Using the solvent mixture of ethanol and water, the particle size distribution was narrower in a mixture containing 10-30 parts of water. The average particle sizes decreased with increasing the dispersant concentration, polarity or the dispersion medium, or agitation rate. Increases in polymerization temperature or reaction time resulted in an increase in the average particle size. This article elucidates the synthesis techniques for super-ft.ne, monodispersed copolymer formation by the theories of the solubility parameter, and dispersant anchoring.

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a Department of Photographic Science and Printing Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
b Multidisciplinary of Petrochemistry and Polymer, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand.

* Corresponding author.

Received August 14, 1998