Solubility of water in polymers—atomistic simulations

The combination of the thermodynamic-integration approach and Widom's particle-insertion method is shown to be appropriate to determine the excess chemical potential of water in dense, amorphous polymer microstructures from MD simulation at an atomistically detailed level. The two-step method is applied to bisphenol-A–polycarbonate (BPA–PC) and polyvinylalcohol (PVA). The results are compared to previously published calculations on water sorption of various polyamides and show the applicability of the two-step method for the calculation of the excess chemical potential of water in a variety of polymer materials to obtain an estimate of their water sorption behavior.