Evidence for diffusion-controlled recombination kinetics in model wormlike micelles

We study the recombination kinetics and stress relaxation in a generic reversible polymer model, which is believed to resemble a wormlike micellar system. We find evidence that, at high concentrations, the recombination kinetics in this model cannot be described by a mean-field approach, but is diffusion-controlled and dominated by self-recombination events. We observe that the long-time stress relaxation of unentangled chains is proportional to √1/texp[-t/Τ_relax], with a relaxation time given by Τ_relax = (t_h^2/3Τ _{〈 L 〉}^1/3 where t_h is the average diffusion time to a different chain end, and Τ_{〈 L 〉} is the characteristic relaxation time of a system of "dead" polymers of length equal to the average micellar length. A recombination activation barrier is needed to drive the system towards mean-field behaviour. This, in its turn, is often required in order to realistically model the rheology and dynamics of wormlike micelles.