Viscosity studies of pluronic F127 in aqueous solution

Abstract

The viscosities of the triblock copolymer F127 [(poly(ethylene oxide))₁06-(poly(propylene oxide))₇0-(poly(ethylene oxide))₁06] in water and the corresponding pluronic F127/water/SDS (sodium dodecyl sulphate) system have been studied as a function of concentration and temperature. The results are discussed in terms of the solution microstructures and transitions between the dissociated state at low temperatures and an associated state at high temperatures. Above 35 °C, the system is consistent with hard sphere dispersions. As the temperature is lowered below 35 °C, the viscosity data indicate a progressive weakening of the structure. This is consistent with a critical micellisation temperature in the region 20 to 30 °C, and a critical micellisation concentration in the region 25 to 50 °C of ca. 1.0 g/L. Addition of SDS (sodium dodecyl sulphate) leads to micellar softening and micellar dissociation at higher SDS concentrations. Data from dynamic light scattering support the viscosity observations.

Acknowledgements We would like to gratefully acknowledge the Daiwa Anglo-Japanese Foundation for support of this collaboration. We also appreciate stimulating discussions with Dr. D.C. Hone, Mr. M. Wright and Dr. M. Silbert.