A Transferrable Coarse-Grained Force Field for Simulations of Polyethers and Polyether Blends

We developed a transferable coarse-grained (CG) force field to cover polyethers and polyether blends in this work. On the basis of the perturbation theory of liquids and high-temperature expansion, we examined the theoretical foundation of using a temperature-dependent function to represent the nonbonded interactions. Using a mapping rule that balances molecular representation with the degree of coarse-graining, we defined seven CG beads that represent common polyethers. A hybrid parametrization workflow combining bottom-up and top-down approaches was applied to derive the force field parameters. The large ratio between the number of training data and the number of adjustable parameters enables the resulting force field to accurately predict many polymer properties, including cohesive energies, structural parameters, glass-transition temperatures, and surface tensions. In addition, the force field is capable of simulating polyether blends using modified Lorentz-Berthelot combination rules. As a preliminary application, we have investigated the phase behavior of three polyether blends. For immiscible polymers, two glass transitions are identified, which are shown to be correlated to the chain dynamics of each component.