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

摘要

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 (ACVA_(16)). In both polymers, the rheological behavior depended strongly on the amount of surfactant added. For the telechelic and multisticker polymers, the terminal relaxation time T _R exhibited a maximum when the surfactant concentration was augmented (SDS or DTAB). An increase or decrease in the plateau modulus G _0 was observed, depending on the structure of the polymer (telechelic or multisticker).