Sommaire:

Shampoos, lubricants, and other complex fluids display a viscoelastic behavior due to the wormlike micellar networks formed by their surfactants. These networks are an instance of "living polymers", a name recalling the continuous breaking and rejoining of the tubular structures formed by the surfactants.

With a a novel coarse-grained model of complex soft matter networks, we show that they can experience a transient equilibration much longer than their local rearrangements. Our large-scale simulations unveil bottlenecks in the local dynamics that lead to the stagnant global equilibration. In agreement with experimental data, timescales for the thermal activation of single scission events of the network strands may be found up to millisceconds. Yet, the need of overcoming topological constraints through a sequence of intermediate unfavorable structures (dangling ends and eventually branches) originates a slower (power-law) global relaxation of the system, which ends after time scales of seconds. This nontrivial time scales should be considered for estimating the Weissenberg and Deborah numbers in experiments of viscoelastic media.

Pour plus d'informations, merci de contacter Walter J.-C.