The isothermal phase diagram for the system sodium dodecyle sulfonate/n-butanol/20% styrene/water has been determined at 40℃. The polymerization of styrene in O/W, W/O, and BC microemulsions was investigated by using the water-soluble potassium persulfate and oil- soluble azo-bis-isobutyronitrile (AIBN) as initiators. The relationship between the conversion rate of styrene, the molecular weight of polystyrene and the water content of the system was obtained, and the effect of microemulsion structures on the polymerization of styrene was also discussed. With the microscope, the feature of polystyrene particles was observed and the diameter was 20～60nm. At the same time, in order to analyze the polymerization of styrene, the solubilization site of styrene in microemulsion drops was studied by ^1H NMR spectra.

Key words: POLYMERIZATION, STYRENE, MICROEMUSION, PROTON MAGNETIC RESONANCE SPECTROMETRY, PHASE EQUILIBRIUM, POLYSTYRENE, DISSOLVING