While the aging of polymer glasses puts a burden on the long-term functionality of products made out of them, a bottom-up (i.e., molecular-level based) understanding of the parallel aging mechanisms acting is still missing. Since aging mechanisms affect the polymer at the molecular scale, investigation of the change in macroscale properties using atomistically-detailed molecular simulations can provide crucial insights into the processes of physical and chemical aging (e.g., exposure of polymers to aggressive chemicals), as well as UV-induced degradation. By introducing a two-level approach to the treatment of aging, i.e., discerning between individual low-level events and collective phenomena, we have set up a unified description of the time-evolution of a physically aging specimen exposed to reactive chemicals. The first results have been encouraging, i.e., the prediction, from atomistic simulations, of the time-scales of the subglass relaxations of polystyrene and the calculation of diffusivity of reactant polymers within a polymer matrix. However, the goals of incorporating chemical reactions and irradiation-induced degradation are still challenging.

Acknowledgments: Financial support by the Dutch Polymer Institute (DPI), project no. 745ft14 and no. 820.