Construction of a highly coarse-grained model for cis-polybutadiene with slip-springs for rheological properties*

We present a method to use dynamical observables from atomist and Lennard-Jones beads spring simulations to construct a highly coarse-grained model via a top-down parameter matching.
As a result of the coarse-graining the nonbonded interactions are soft in this model, hence we represent entanglements via slip-springs.

Parameter passing for the equilibrium static properties is well understood.
For dynamic properties, this is more challenging as the system exhibit a spectrum of relaxation times.
Our model allows a decoupled tuning of both effects, such that we can match both, the time scales and the average number of fluctuating slip-springs to mimic entanglement effects.
The matching is performed for shorter chains and successfully transferred to higher molecular weights.

Our model allows simulations with molecular weights up to 100 000 g/mol for up to 100 µs with an implementation based on HOOMD-blue for GPU hardware.
This enables measurements of the stress autocorrelation function G(t) to predict rheological properties.