Formations of polyvinyltoluene microlatexes in quaternary oil in water cetyltrimethylammonium bromide microemulsions

Abstract

Polymerization of vinyltoluene (VT) in quaternary microemulsions containing cetyltrimethylammonium bromide (CTAB) as the cationic surfactant is studied using laser Raman spectroscopy (LRS) and dilatometry. The influences of water soluble (potassium peroxodisulphate, ammonium peroxodisulphate) and oil soluble (azobisisobutyronitrile, benzoyl peroxide) initiators, monomer, surfactant, cosurfactants (n-alcohol and bifunctional alcohols) and temperature on the rates of polymerization (R _p), energy of activation (Ea), particle diameter (D), number of polymer particles (N _p), molecular weight of polyvinyltoluene (M _v) and number of polymer chains per latex particle (N _pc) are investigated. The dependencies of the kinetic and latex size parameters on the initiators and cosurfactants are discussed in terms of the efficiency of the initiators in initiating the polymerization and on the interfacial partitioning behavior of various cosurfactants. The polymerization mechanism seems to follow Smith Ewart Case II hypothesis with two distinct rate regions. Final polymer microlatexes are found to lie within 10–50 nm as observed by transmission electron microscopy (TEM). Molecular weights are in the range of (1 to 5)×10⁶. Each latex particle contains one to three polymer chains.