The viscoelasticity of aqueous micellar solutions of two oxyethylene/oxybutylene block copolymers (E
92B
18 andB
20E
510) has been investigated using a torsional resonator operated at 26 kHz. For both systems considered, valuesof the dynamic viscosity (
![](/isubscribe/journals/langd5/22/i16/eqn/la0607860e10001.gif)
) point to partial draining of the micellar corona induced by the high-frequency oscillatoryfield. At low effective volume fractions, values of the elastic modulus (
![](/isubscribe/journals/langd5/22/i16/eqn/la0607860e10002.gif)
) indicate that the repulsive interactionsbetween micelles can be modeled by a power law function
u(
r)
![](/images/entities/prop.gif)
1/
r![](/images/gifchars/nu.gif)
with exponents close to 13
and 6 for copolymersE
92B
18 and B
20E
510 respectively. At a critical copolymer concentration (
c*) plots of log(
![](/isubscribe/journals/langd5/22/i16/eqn/la0607860e10003.gif)
) against log(
c) deviate fromthe straight lines established at low concentrations, implying that the systems undergo ergodic/nonergodic transitions.