Abstract
The effect of phenol solubilization on the behavior of (ethylene oxide)(78)-propylene oxide)(30)-(propylene oxide)(78) (EO78-PO30-EO78) tri-block copolymer, Pluronic F68 (F68), in aqueous suspensions was investigated by rheology. We have shown that for the ternary F68/water/phenol mixture, the rheological properties and the conformational changes of F68 depended strongly on the amounts of phenol. The 20% F68 suspensions begin with a Newtonian behavior for small amounts of phenol and lose this behavior to become a non-Newtonian liquid plastic with increasing phenol concentrations (50% phenol); then the suspension became Newtonian again for 75% and 100% phenol. The results are attributed to the addition of phenol resulting in a sphere-to-rod micellar transition.