ATOMISTICALLY MODELING THE CHEMICAL-POTENTIAL OF SMALL MOLECULES IN DENSE POLYMER MICROSTRUCTURES .1. METHOD

A method is presented to estimate the excess chemical potential of sol utes in dense polymer microstructures with a combination of the thermo dynamic-integration approach and Widom's particle insertion from MD ru ns under constant NVT conditions on an atomistic level. The results ob tained for pure water systems show good agreement with other calculate d values and with experimental data. The calculated excess chemical po tential of water dissolved in a wet polyamide(6) (PA-6) matrix is comp ared with the corresponding value of pure water. This gives a qualitat ive estimation of the equilibrium water content of amorphous PA-6.