From miscibility to aging: Insight and predictions using the segmental interaction energy

In this talk we elevate the practical importance of segmental interaction energies by demonstrating their influence over a very wide span of behavior, from dynamic to thermodynamic. Using a variety of experimental data, alongside equation of state results segmental interaction energies and molecular size, we draw bright lines from thermodynamic characterization to predictions for the glass transition temperature, segmental times associated with alpha relaxation, and both activation energies and relaxation times for the small scale cooperative motions that enable the newly-revealed Slow Arrhenius Process (SAP). The latter is connected to phenomena ranging from dewetting and flow to crystallization, lipid transfer, and aging. We also quantify an exceptionally strong, direct, correlation between e and the thermal expansion coefficient, which broadens the route for thermodynamic characterization to methods such as ellipsometry. Going further, we demonstrate that dynamic measurements, specifically on SAP relaxations, can be used to characterize segmental interactions. We complete the circle by showing that the resulting dynamics-derived segmental interaction energies are effective in making verifiable predictions about polymer miscibility.