  Photon correlation spectroscopy and rheological measurements are performed to
investigate the microscopic dynamics and mechanical responses of aqueous
solutions of triblock copolymers and aqueous mixtures of triblock copolymers
and anionic surfactants. Increasing the concentration of triblock copolymers
results in a sharp increase in the magnitude of the complex moduli
characterising the samples. This is understood in terms of the changes in the
aggregation and packing behaviours of the copolymers and the constraints
imposed upon their dynamics due to increased close packing. The addition of
suitable quantities of an anionic surfactant to a strongly elastic copolymer
solution results in a decrease in the complex moduli of the samples by several
decades. It is argued that the shape anisotropy and size polydispersity of the
micelles comprising mixtures cause dramatic changes in the packing behaviour,
resulting in sample unjamming and the observed decrease in complex moduli.
Finally, a phase diagram is constructed in the temperature-surfactant
concentration plane to summarise the jamming-unjamming behaviour of aggregates
constituting triblock copolymer-anionic surfactant mixtures.
