Dynamics and Rheology of <i>cis</i>-1,4-Polybutadiene melts through Systematic Bottom-up Coarse-grained Simulations

Due to the broad range of time and length scales involved, the simulation of high molecular weight polymer melts is not straightforward.
Here we present the results of coarse-grained (CG) simulations for the dynamics and linear viscoelastic properties of cis-1,4-polybutadiene (cPB) melts. The CG model is parametrized based on an atomistic model.
At the CG level, atoms of one monomer of cPB are mapped into one CG bead. The model is a moderately CG presentation of cPB which preserves its chemical identity. Also, the nonbonded interactions of the model are hard enough to prevent chain crossings and preserving entanglement effects. The CG potentials are derived by matching local structural distributions of the CG model to those of
the atomistic model through iterative Boltzmann inversion. For matching CG and atomistic dynamics, the CG time is scaled by a time scaling factor, which compensates its lower monomeric friction coefficient. Time scaling factor is chain length dependent, however, it converges to a constant value for large chains. cPB chains of various lengths, covering the range from the unentangled to the moderately entangled regime are studied. The simulation results are compared with the experimental data.