(86c) Predictive Virtual Synthesis and Characterization of Glassy Materials

The characterization of amorphous glassy polymers presents significant challenges due to their irregular and disordered nature. Porous polymers, for example, are commonly characterized experimentally by gas adsorption, from which properties such as surface areas and pore volumes are commonly reported. However, these properties are obtained indirectly through the application of models based on a number of assumptions for the adsorption processes and pore geometry. Molecular simulations are a valuable complementary tool for the characterization of amorphous porous polymers that can provide molecular-level detail of their structures and adsorption phenomena.

In this talk, a general simulation methodology for the predictive modeling of complex amorphous materials is presented. The methodology was applied to a variety of glassy linear polymers, including polycarbonate, polyetherimide, and rigid polymers of intrinsic microporosity (PIMs), as well as organic molecules of intrinsic microporosity (OMIMs). Excellent agreement with experimental data was found for densities, surface areas, and wide-angle X-ray scattering (WAXS), among others. Additionally, the ability of molecular simulations to help analyze and interpret experimental results is illustrated for WAXS and gas adsorption. For example, molecular models of OMIMs were utilized to facilitate the assignment of WAXS features to specific intra- and intermolecular distances within the system and provide valuable information about their packing behavior. Also, the applicability of the commonly used BET theory for PIMs and OMIMs was explored through nitrogen gas adsorption simulations. These examples show how the synergy of molecular simulations and experiments has the possibility to more effectively and efficiently further the understanding and design of glassy amorphous materials.