A temperature (T)-dependent coarse-grained (CG) Hamiltonian of polyethylene glycol/oxide (PEG/PEO) in aqueous solution is reported to be used in implicit-solvent material models in a wide temperature (i.e., solvent quality) range. The T-dependent nonbonded CG interactions are derived from a combined "bottom-up" and "top-down" approach. The pair potentials calculated from atomistic replica-exchange molecular dynamics simulations in combination with the iterative Boltzmann inversion are postrefined by benchmarking to experimental data of the radius of gyration. For better handling and a fully continuous transferability in T-space, the pair potentials are conveniently truncated and mapped to an analytic formula with three structural parameters expressed as explicit continuous functions of T. It is then demonstrated that this model without further adjustments successfully reproduces other experimentally known key thermodynamic properties of semidilute PEG solutions such as the full equation of state (i.e., T-dependent osmotic pressure) for various chain lengths as well as their cloud point (or collapse) temperature.

Department of Physical Chemistry University of Chemistry and Technology Prague Technická 5 CZ 16628 Praha 6 Czech Republic

Institut für Physik Humboldt Universität zu Berlin Newtonstraße 15 D 12489 Berlin Germany

Institut für Weiche Materie und Funktionale Materialen Helmholtz Zentrum Berlin Hahn Meitner Platz 1 D 14109 Berlin Germany

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Weakly hydrated anions bind to polymers but not monomers in aqueous solutions