Synthesis of polymerizable anionic surfactants and their emulsion copolymerization with styrene

Two polymerizable ionic surfactants sodium 4-(omega -acryloyloxyalkyl)oxy b enzene sulfonate (SABS-n, n = 8 or 10) have been synthesized and polymerize d. Their critical micelle concentrations (CMC) were determined to be 9.40 x 10(-3) M and 2.02 x 10(-3) M at 25 degreesC for SABS-8 and SABS-10, respec tively. The rate of micellar polymerization of SABS-8 or SABS-10 was found to be proportional to half an order of the concentration of ammonium persul fate (APS) and first order of the surfactant concentration. Their activatio n energies of micellar polymerization were relatively low, that is, 58.2 kJ mol(-1) for SABS-8 and 45.4 kJ mol(-1) for SABS-10. The monomer reactivity ratios for emulsion copolymerization of SABS-8 (M-1) and styrene (M-2) wer e determined to be r(1) = 0.47 and r(2) = 3.91. These emulsion copolymeriza tions produced small latex particles ranging from 16 to 30 nm in diameter. XPS analysis shows that SABS-8 was significantly enriched on the surface of latex particles, for example, 63.4% surface coverage on latex particles by 16 wt % SABS-8 in the feed composition. The surface coverage of about 20% polymerized surfactant on the surface of latex particles was found to be su fficient to stabilize latexes under heating at 70 degreesC for at least one month.