ROLE OF POLYMER-POLYMER MONOMER INTERACTIONS IN THE STABILIZATION OF EMULSIFIER-FREE LATEXES

The stability of emulsifier-free latexes of hydrophobic monomers (styr ene, butyl acrylate), hydrophilized by water-soluble (acrylic and meth acrylic acids) or by highly hydrophilic (methyl methacrylate) monomers , has been studied in order to elucidate the role of polymer-polymer a nd polymer-monomer interactions. Polymer-polymer interactions were est imated in terms of the theory of the stability, thus making it possibl e to analyze the contribution of the electrostatic and structural comp onents to the total energy of interaction of polymer particles during their hydrophilization using two methods. The difference in the influe nce of hydrophilizing monomers on the stability of the particles was d iscovered, i.e., improved stability with the addition of monomeric aci d and maximum stability under hydrophilization by methyl methacrylate. These effects were explained by different patterns in the change of t he electrostatic and structural components. When latex is hydrophilize d by acid, a substantial decrease in the structural component, as comp ared to the electrostatic one, is observed, whereas in the case of hyd rophilic monomers the change of the components is commensurable. A sig nificant increase in the amount of coagulum at a high content of methy l methacrylate is associated with a smaller parameter of the monomer-p olymer interaction in comparison with the hydrophobic system that faci litates the swelling of a polymer, enhances the mobility of the disper sed monomer-polymer phase, and accelerates the coalescence of the part icles during polymerization.