Dynamical monte carlo study of equilibrium polymers. II. The role of rings

We investigate by means of a number of different dynamical Monte Carlo simu lation methods the self-assembly of equilibrium polymers in dilute, semidil ute and concentrated solutions under good-solvent conditions. In our simula tions, both linear chains and closed loops compete for the monomers, expand ing on earlier work in which loop formation was disallowed. Our findings sh ow that the conformational properties of the linear chains, as well as the shape of their size distribution function, are not altered by the formation of rings. Rings only seem to deplete material from the solution available to the linear chains. In agreement with scaling theory, the rings obey an a lgebraic size distribution, whereas the linear chains conform to a Schultz- Zimm type of distribution in dilute solution, and to an exponential distrib ution in semidilute and concentrated solution. A diagram presenting differe nt states of aggregation, including monomer-, ring-, and chain-dominated re gimes, is given. The relevance of our work in the context of experiment is discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)50740-5].