Interactions between the nonionic surfactant and polyacrylamide studied bylight scattering and viscometry

Light scattering and viscometric measurements were made on ternary mixtures of high molecular weight polyacrylamide (PAM), and the nonionic surfactant , Triton X-100 (TX-100) in aqueous solution. The binary solutions of polyme r and surfactant in aqueous media were also studied. In the ternary system, the solution viscosity and translational diffusion coefficients were deter mined at 30 degrees C in terms of (a) the surfactant concentration at fixed PAM concentration, (b) the PAM concentration at fixed surfactant concentra tion, and (c) the PAM molecular weight. The surfactant concentration was va ried by five orders of magnitude, the mean diffusion coefficient decreased slightly at first until reaching a minimum and then rose toward an asymptot ic value which was identical to that of a single micelle. Near the cmc, the binding of the surfactant onto a polymer chain induced a slight chain expa nsion, but surprisingly the specific viscosity diminished. DLS shows a comp onent owing to free micelle diffusion at concentrations above 1 mM of TX-10 0. This indicates the saturation point of binding between PAM and TX-100. D ifferent molecular weights of PAM interacted with the surfactant quite simi larly. (C) 1999 Elsevier Science Ltd. All rights reserved.