Predicting optimal chain lengths in atomistic simulations of solvated polymers

Currently, clear guidance is not available for determining the minimum practical chain lengths needed for achieving reasonable convergence when performing atomistic simulations of common synthetic polymers. Here, we analyze a collection of polymers, including polypropylene (PP), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethylene glycol (PEG), poly(methyl methacrylate) (PMMA), polystyrene (PS), and polyvinyl chloride (PVC), with chain lengths varying from 5 to 240 repeat units. We exclusively focus on solvated polymer systems, and we report the convergence of several characteristic properties, such as radial distribution functions (RDFs), surface area per repeat unit (SASA/N), ratio of mean squared end-to-end distance to mean squared radius of gyration (⟨R2⟩⟨Rg2⟩), and surface electrostatic potential distributions. Based on these data, we propose a general relationship for identifying minimum practical chain lengths for performing atomistic simulations of solvated linear synthetic polymers, which is based on the SASA/N.