We have carried out extensive high-level quantum chemistry studies of the geometry, charge distribution, conformational energies, and hydrogen-bonding energies of model compounds for a family of Estane thermoplastic urethanes (TPUs). Upon the basis of these studies, we have parametrized a classical potential for use in atomistic simulations of Estane TPUs that can also be applied directly or with minor extensions to a wide variety of polyesters and polyurethanes.