Polymerizable microemulsions: some criteria to achieve an optimal formulation

Two types of water-soluble polymers have been prepared via a microemulsion polymerization route: (i) copolymers of acrylamide with sodium-2-acrylamido -2-methylpropanesulfonate and (ii) copolymers of acrylamide and sodium acry late hydrophobically modified with an amphiphilic monomer. The formulation of the polymerizable microemulsions was optimized by using cohesive energy ratio (CER) and hydrophile-lipophile balance (HLB) concepts. In addition, t he role played by the nature of the surfactants and the monomers was thorou ghly investigated. The best formulation was obtained for high HLB values (8 -11), in favor of microemulsions with a bicontinuous structure. The process was shown to yield remarkably stable, clear microlatexes of moderate parti cle size containing up to 25% high molecular weight polymer in the medium, in contrast to inverse latexes prepared by using classical emulsions which are unstable and turbid. These materials are of great interest for industri al applications. (C) 1999 Elsevier Science B.V. All rights reserved.