Journal of Applied Polymer Science, Vol.60, No.3, 293-304, 1996
Influences of Initiators and Cosurfactants on Microemulsion Polymerization of Vinyltoluene
Influences of various cosurfactants (CS) (n-alcohols and bifunctional alcohols) and initiators (hydrophilic potassiumperoxodisulphate; ammoniumperoxodisulphate and hydrophobic azobisisobutyronitrile; benzoylperoxide) on the polymerization of vinyltoluene-sodium dodecylsulphate-water-CS microemulsions (oil/water mu Es) are studied with respect to the rates of polymerization, molecular weight of polymer, number, and size of polymer particles and energy of activation (E(a)). Laser Raman spectroscopy and dilatometry are employed to study the kinetics. Smith Ewart Case II hypothesis seems to be followed in the vinyltoluene mu E polymerization. Stable polymer microlatices with high molecular weights (>10(6)) are obtained and particle sizes are found to lie within 10-50 nm as observed from the transmission electron microscopy (TEM) photographs. E(a) values varied with different cosurfactants and were found to be comparable with other monomers. Studies of the effects of pH, salt (Na2SO4), and inhibitor (hydroquinone) on the microemulsion polymerization showed that optimum pH = 7.0. Higher rates were seen in the absence of salt, and chain transfers to inhibitors take place.
Keywords:IN-WATER MICROEMULSIONS;METHYL-METHACRYLATE;INVERSE MICROEMULSIONS;EMULSION POLYMERIZATIONS;LATEX-PARTICLES;FREE-RADICALS;STYRENE;SPECTROSCOPY;RAMAN;SIZE