Computational confirmation of scaling predictions for equilibrium polymers

We report the results of extensive dynamic Monte Carlo simulations of systems of self-assembled Equilibrium Polymers without rings in good solvent. Confirming recent theoretical predictions, the mean chain length is found to scale as < L > = L* (phi/phi*)(alpha)proportional to phi(alpha) exp[delta E] with exponents alpha(d) = delta d = 1/(1 + gamma) approximate to 0.46 and alpha(s) = [1 + (gamma - 1)/(upsilon d - 1)]/2 approximate to 0.60, delta(s) = 1/2 in the dilute and semi-dilute limits, respectively. The average size of the micelles, as measured by the end-to-end distance and the radius of gyration, follows a very similar crossover scaling to that of conventional quenched polymer chains. In the semi-dilute regime, the chain size distribution is found to be exponential, crossing over to a Schultz-Zimm-type distribution in the dilute limit. The very large size of our simulations (which involve mean chain lengths up to 5000, even at high polymer densities) allows also an accurate determination of the self-avoiding walk susceptibility exponent gamma = 1.165 +/- 0.01.