Aqueous solutions of associative poly(acrylates): Bulk and interfacial properties

Abstract

Hydrophobically modified polyelectrolytes, such as polyacrylic acids (PAA) are widely used as technological viscosifiers. At the same time, they are of great academic interest in view of wide possibilities for fine-tuning of their aqueous solution properties. The latter strongly depend on the quantity of added low-molecular-mass electrolytes and are sensitive to the pH-value of the solution. The present study explores the bulk and interfacial characteristics of aqueous solutions of two polyacrylic acids: PAA150C10 (MW=150000) and PAA150C12 (MW=150000), randomly grafted with 3mol% decyl (C10) and dodecyl (C12) chains. Bulk viscoelastic properties of PAA150C10 and PAA150C12 are explored; dynamic, equilibrium and rheological properties of the adsorption layers at solution/air interface are studied, as well. For the same systems, microscopic foam films are investigated (drainage kinetics, disjoining pressure vs. film thickness isotherms, stability, etc.). The obtained results contain valuable new information which may be related to the interplay of the specific interactions in the particular formulations and to the possible conformation changes of these amphiphilic polymers. The experimental data provide additional evidences for the response of the investigated aqueous systems to well-defined changes in the experimental conditions (pH, addition of low-molecular-mass electrolytes, etc.).