  Motivated by the deficiencies of the previous MARTINI models of poly(ethylene
oxide) (PEO), we present a new model featuring a high degree of
transferability. The model is parametrized on (a) a set of 8 free energies of
transfer of dimethoxyethane (PEO dimer) from water to solvents of varying
polarity; (b) the radius of gyration in water at high dilution; and (c)
matching angle and dihedral distributions from atomistic simulations. We
demonstrate that our model behaves well in five different areas of application:
(1) it produces accurate densities and phase behavior or small PEO oligomers
and water mixtures; (2) it yields chain dimensions in good agreement with the
experiment in three different solvents (water, diglyme, and benzene) over a
broad range of molecular weights (1.2 kg/mol to 21 kg/mol); (3) it reproduces
qualitatively the structural features of lipid bilayers containing PEGylated
lipids in the brush and mushroom regime; (4) it is able to reproduce the phase
behavior of several PEO-based nonionic surfactants in water; and (5) it can be
combined with the existing MARTINI PS to model PS/PEO block copolymers.
Overall, the new PEO model outperforms previous models and features a high
degree of transferability.
