Gelation of micellar block polyelectrolytes: Evidence of glassy behavior in an attractive system

We present small-angle neutron scattering and rheology for micellar solutions of polystyrene-poly(acrylic acid) block copolymers that can be regarded as attractive colloids. These systems form gels at,high effective micellar volume fractions (phi > 0.64) that are suggestive of disordered colloidal glasses. At the gel point, the solution rheology follows the scaling predicted by classical percolation theory, with G' similar to G" similar to omega(Delta). We argue that this scaling could be due either to formation of a percolated network or to a pretransitional glassy phase.