A transient network of telechelic polymers and microspheres: structure andrheology

We study the structure and dynamics of a transient network composed of drop lets of microemulsion connected by telechelic polymers. The polymer induces a bridging attraction between droplets without changing their shape. A vis coelastic behaviour is induced in the initially liquid solution, characteri zed in the linear regime by a stretched-exponential stress relaxation. We a nalyse this relaxation in the light of classical theories of transient netw orks. The rob of the elastic reorganizations in the deformed network is emp hasized. In the non-linear regime,a fast relaxation dynamics is followed by a second one having the same rate as that in the linear regime. This behav iour, in step strain experiments, should induce a non-monotonic behaviour i n the elastic component of the stress for a constant shear rate. However, w e obtain in this case a singularity in the how curve very different from th e one observed in other systems, that we interpret in terms of fracture beh aviour.