St-BA-AOS copolymer emulsion was synthesized via the preemulsified emulsion polymerization, with styrene (St), butyl acrylate (BA), and sodium alpha-olefin sulfonate (AOS) as the polymerizable emulsifier. Semi-continuous method of the polymerization was determined by measuring the reactivity ratios of AOS and two monomers. The influences of the feeding method, the reaction temperature, time and AOS amount on the emulsion polymerization were investigated, then the most suitable polymerizing conditions were obtained. The analysis of the profiles of IR, NMR, DSC and Laser particle size demonstrated that the copolymerization occurred among St, BA and AOS to generate P(St-BA-AOS) successfully, and hydrophilic sulfonic acid groups containing the copolymer were conducive to emulsion stability. Based on the study, the influences of the dosages of AOS on the latex solid content and average particle size were discussed. The result showed that with the increase of AOS amount, the latex solid content increased and average particle size of latex reduced, e.g., at the 2% mass amount of AOS 45.01% of the latex solid content, 74 nm of average diameter, 0.08 of particle size distribution and 23.17 ℃ of T_g were obtained. The results of TEM showed that the copolymer emulsion with smaller particle size and more uniform size distribution could be obtained by using polymerizable emulsifier AOS instead of the same amount of sodium lauryl sulfate.

Key words: emulsion polymerization, polymerizable emulsifier, sodium alpha-olefin sulfonate, acrylate