Size control of polystyrene beads by multistage seeded emulsion polymerization

Citation
Se. Shim et al., Size control of polystyrene beads by multistage seeded emulsion polymerization, J APPL POLY, 71(13), 1999, pp. 2259-2269
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science","Material Science & Engineering
Journal title
JOURNAL OF APPLIED POLYMER SCIENCE
ISSN journal
0021-8995 → ACNP
Volume
71
Issue
13
Year of publication
1999
Pages
2259 - 2269
Database
ISI
SICI code
0021-8995(19990328)71:13<2259:SCOPBB>2.0.ZU;2-U
Abstract
Micron-sized monodisperse crosslinked polystyrene (PS) beads have been prep ared by a multistage emulsion polymerization using styrene monomer, divinyl benzene crosslinking agent, and potassium persulfate initiator in the absen ce of emulsifier. In the first stage of the reaction, the lower the reactio n temperature, the larger the bead size obtained. In the later stages of th e reaction, the particle size is increased with the initiator concentration and monomer content. Particle nucleation of the preexisting polymer seed o f 0.7-0.8 mu m in diameter is prepared at 60 degrees C, then the monodisper se crosslinked PS beads > 2 mu m are synthesized up to the third stage of t he reaction. As the particle size grows, the number of free radicals in the growing particles increases, and the conversion of the next stage is conti nuously increased. The reaction mechanism is suggested that the continuous polymerization be conducted due to the diffusion of monomer into the preexi sting particles to induce spherical beads in the later stages of the reacti on. Otherwise, phase separation or the formation of protrusion by the captu re of free radicals will be taking place. (C) 1999 John Wiley & Sons, Inc.