Effect of surfactant on the viscoelastic behavior of semidilute solution of two different families of water-soluble copolymers prepared by solution polymerization

Abstract

The interactions between hydrophobically modified polyacrylamides (HMPAM) and the anionic surfactant SDS (sodium dodecyl sulfate) and/or the cationic surfactant DTAB (dodecyltrimethylammonium bromide) were studied in aqueous solution using steady flows and oscillatory rheological experiments. The structure of the HMPAM used consisted of a telechelic polymer (with hydrophobic groups at the chain ends) and a multisticker polymer (with hydrophobic groups along the polymer chain). The multisticker polymer was prepared with acrylamide and N-hexadecylacrylamide (HDAM), whereas the telechelic polymer was prepared with acrylamide and a hydrophobic initiator that was derived from 4,4′-azobis(4-cyanopentanoic acid) (ACVA) and contained a long linear chain of 16 carbon atoms (ACVA16). In both polymers, the rheological behavior depended strongly on the amount of surfactant added. For the telechelic and multisticker polymers, the terminal relaxation time TR exhibited a maximum when the surfactant concentration was augmented (SDS or DTAB). An increase or decrease in the plateau modulus G0 was observed, depending on the structure of the polymer (telechelic or multisticker).