Development of Transferable Nonbonded Interactions between Coarse-Grained Hydrocarbon and Water Models

Interactions between water and hydrocarbons play a significant role in chemical, physical, and biological processes. Here, we present a set of force-field (FF) parameters that define the interactions between coarse-grained (CG) hydrocarbon models ( An , Y. J. Phys. Chem. B , 2018 , 122 , 7143 - 7153 ) and one-site water model ( Bejagam , K. K. J. Phys. Chem. B , 2018 , 122 , 1958 - 1971 ) developed in our recent work. The nonbonded FF interactions between various hydrocarbon beads and the water beads are represented by the 12-6 Lennard-Jones potential. The FF parameters were optimized to reproduce the experimentally measured Gibbs hydration free energies of selected hydrocarbon models (decane and hexadecane with 2:1 mapping scheme and nonane and pentadecane with 3:1 mapping scheme) and the interfacial tensions of decane and nonane models at 300 K. The predicted values of Gibbs hydration free energies of CG decane, hexadecane, nonane, and pentadecane models by the optimized FF parameters were within 8, 12, 11, and 4% of their corresponding experimental values, respectively. These new optimized FF parameters were transferable when used to calculate the Gibbs hydration free energies of different hydrocarbons ranging from pentane to heptadecane at 300 K (minimum error ∼0.5%, and maximum error ∼40.8%). Furthermore, the interfacial tensions of the CG hydrocarbon models calculated by using these new FF parameters showed good agreement with their corresponding experimental values at 300 K. Homogeneous mixtures of CG water and hydrocarbon models were able to exhibit the phase segregation during 1 μs. These new nonbonded interaction parameters were expected to be utilized in modeling the interactions between water and polymer backbones represented with hydrocarbon beads.