Associating Polyelectrolytes with Perfluoroalkyl Side Chains: Aggregation in Aqueous Solution, Association with Surfactants, and Comparison with Hydrogenated Analogues

Abstract

Derivatives of poly(sodium acrylate) bearing a few mole percent of perfluoroalkyl side chains were synthesized. Their solution properties were investigated by rheology and compared to those of their hydrogenated analogues. As the hydrogenated modified polymers, these new materials display an associating behavior. In semidilute solution the modified polymer exhibits viscosities of several orders of magnitude higher than the unmodified poly(sodium acrylate). However, this viscosifying effect is more pronounced for the perfluorinated derivatives. By comparing the rheological behaviors we find that a polymer bearing C7F15CH2 side groups is as associative as a polymer containing the same fraction of C13H27 chains. This is in agreement with Ravey and Stébé's1 conclusions concerning surfactant association that a CF2 is equivalent to 1.7CH2 as regards its hydrophobicity. Mixtures of the perfluorinated polymers with their hydrogenated analogues or with hydrogenated surfactants were successively studied. For low modification ratios (≤7 mol %) and at concentration ranges close to the critical aggregation concentration the mixing is not ideal. This is in line with the nonideal behavior displayed by mixtures of perfluorinated and hydrogenated surfactants.