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Abstract
A gravitational field-flow fractionation (GrFFF) was employed to study the influence of various reaction parameters in emulsion polymerization on size distribution of polymeric latex beads. Micron-sized polystyrene (PS) latex beads were synthesized by conventional emulsion polymerization. The reaction parameters such as the stirring rate (rpm), reaction time, concentration of azobisisobutyronitrile (AIBN) and polyvinylpyrrolidone (PVP), were systematically varied. Then the PS beads were analyzed by GrFFF for size determination. It was found that the mean diameter and the size distribution of the PS latex beads change as some of the reaction parameters change. No clear trends were observed in the mean diameter and the coefficient of variation (CV) with the stirring rate in the range of 60 to 300 rpm, or with the reaction time in the range of 13 to 24 hrs. A clear trend of increase in the mean diameter with the AIBN concentration was observed, suggesting the particle size can be controlled by varying the AIBN concentration without affecting the size distribution much. It was also found that the mean diameter tends to decrease as the PVP concentration increases while the CV tends to increase. Results obtained from GrFFF were compared with those obtained from photon-correlation spectroscopy (PCS) and optical microscopy (OM).
ACKNOWLEDGMENTS
Some of authors were financially supported by the 2nd stage BK21 project. This work was supported by the Korea Foundation for International Cooperation of Science & Technology (KICOS) through a grant provided by the Korean Ministry of Science & Technology (MOST) in K20713000009-07B0100-00910.
Notes
a mean diameter.
b CV of mass-based size distribution.
c mean diameter.
d CV of number-based size distribution.