A comparative study of polyethylene oxide (PEO) using different coarse-graining methods

Polyethylene oxide (PEO) holds significant importance in the field of batteries due to its high processability, intrinsic properties, and potential for high ionic conductivity. Achieving simulation at different scales is crucial for gaining a comprehensive understanding of its properties and thus improving them. In this context, we conducted a comparative study on the molecular physical structure, thermodynamic, and dynamic properties of PEO using three distinct coarse-grained (CG) procedures and all-atom (AA) simulations. The three CG simulation procedures involved modeling with MARTINI forcefield, SPICA forcefield, and an IBI derived potential from AA simulations. The AA simulation has been performed using the class 2 pcff+ forcefield. The ensuing simulated densities align significantly with the literature data, indicating the reliability of our approach. The solubility parameter from the AA simulation closely corresponds to literature reported values. MARTINI and SPICA yield almost similar solubility parameters, consistent with the similar density predicted by both the forcefields. Notably, SPICA forcefield closely reproduces the intermolecular structure of atomistic systems, as evidenced by radial distribution function (RDF). It also comprehensively replicates the distribution of radius of gyration (Rg) and the end-to-end distance (Re) of the atomistic samples. IBI ranks second to SPICA in emulating the structural properties of the atomistic systems, such as Rg, Re, and RDF. However, IBI falls short in accurately representing the solubility parameter of the amorphous PEO samples, while MARTINI does not provide an accurate representation of the structural properties of the systems. The use of SPICA forcefield results in enhanced dynamics of the systems in comparison with IBI and MARTINI.