Molecular dynamics simulation study of nonconcatenated ring polymers in a melt. I. Statics

Molecular dynamics simulations were conducted to investigate the structural properties of melts of nonconcatenated ring polymers and compared to melts of linear polymers. The longest rings were composed of N = 1600 monomers per chain which corresponds to roughly 57 entanglement lengths for comparable linear polymers. For the rings, the radius of gyration squared, < R-g(2)>, was found to scale as N-4/5 for an intermediate regime and N-2/3 for the larger rings indicating an overall conformation of a crumpled globule. However, almost all beads of the rings are surface beads interacting with beads of other rings, a result also in agreement with a primitive path analysis performed in the next paper [J. D. Halverson, W. Lee, G. S. Grest, A. Y. Grosberg, and K. Kremer, J. Chem. Phys. 134, 204905 (2011)]. Details of the internal conformational properties of the ring and linear polymers as well as their packing are analyzed and compared to current theoretical models. (C) 2011 American Institute of Physics. [doi:10.1063/1.3587137]