Synthesis and characterization of poly[acrylamide-co-(sodium 4-styrenesulfonate)] via inverse microemulsion polymerization

An anionic polyelectrolyte based on acrylamide (Am) and sodium 4-styrenesulfonate (SSS) was synthesized via the inverse microemulsion polymerization technique. The hydrophilic - lipophilic balance (HLB) values of the surfactant and the composition of the inverse microemulsion system were determined using pseudoternary phase diagrams. The reactivity ratios of Am and SSS in inverse microemulsion polymerization were calculated using the Kelen-Tudos method. The optimum HLB value of the surfactant for the inverse microemulsion system was 8.58. The composition of the inverse microemulsion system was surfactants (25 wt%), cyclohexane (59 wt%) and aqueous solution of monomers (16 wt%). Am (r(1)) and SSS (r(2)) reactivity ratios were 0.61 and 1.99, respectively. Monomer reactivity ratios of Am and SSS determined in the present study differ from those reported for solution radical copolymerization. This indicates that the difference in microenvironment in solution and microemulsion plays an important role in governing the reactivity ratios of the monomers. (C) 2009 Society of Chemical Industry