CAPILLARY HYDRODYNAMIC FRACTIONATION (CHDF) AS A TOOL FOR MONITORING THE EVOLUTION OF THE PARTICLE-SIZE DISTRIBUTION DURING MINIEMULSION POLYMERIZATION

Styrene miniemulsions were polymerized at 70 degrees C in an automated reaction calorimeter with samples being periodically removed and anal yzed for their particle size distributions by both transmission electr on microscopy (TEM) and capillary hydrodynamic fractionation (CHDF). I t was shown that the average diameters obtained using CHDF and TEM agr eed to within 5%, while the standard deviations obtained agreed to wit hin 14%. Using CHDF, the evolution of the particle size distribution d uring miniemulsion polymerizations was monitored. This technique showe d the increase in the average particle size with increasing conversion , as expected, and also an increase in the standard deviation with inc reasing conversion. These results are consistent with those obtained u sing TEM. (C) 1995 Academic Press, Inc.