Micellar spheres in a high frequency oscillatory field.
The viscoelasticity of aqueous micellar solutions of two oxyethylene/oxybutylene block copolymers (E(92)B(18) and B(20)E(510)) has been investigated using a torsional resonator operated at 26 kHz. For both systems considered, values of the dynamic viscosity (eta'(infinity)) point to partial draining of the micellar corona induced by the high-frequency oscillatory field. At low effective volume fractions, values of the elastic modulus (G'(infinity)) indicate that the repulsive interactions between micelles can be modeled by a power law function u(r) proportional to 1/r(nu) with exponents close to 13 and 6 for copolymers E(92)B(18) and B(20)E(510) respectively. At a critical copolymer concentration (c*) plots of log(G'(infinity)) against log(c) deviate from the straight lines established at low concentrations, implying that the systems undergo ergodic/nonergodic transitions.
Kelarakis
Antonis
A
Physikalishe Chemie I, Universität Bayreuth, Universitätsstrasse 30, 95440 Bayreuth, Germany. ak385@cornell.edu
Crassous
Jérôme J
JJ
Ballauff
Matthias
M
Yang
Zhuo
Z
Booth
Colin
C