Computationally Assisted Assessment of the Metal-Organic Framework/Polymer Compatibility in Composites Integrating a Rigid Polymer

Density functional theory (DFT) calculations and subsequent classical molecular dynamics (MD) simulations are combined to build and further characterize the interface structure of three binary metal-organic framework (MOF)/polymer composite materials made of ultra-small pore MOFs with distinct surface morphologies, namely, MIL-69, ftw-MOF-ABTC, and ftw-MOF-BPTC, and the 6-FDA-DAM polymer. It is found that the three composites exhibit percolated or independent microvoids of different degrees of interconnectivity, sizes, and positions at the MOF/polymer interface that contribute to decrease the polymer surface coverage, a signature of a relatively poor adhesion between the two components. The ftw-MOF-BPTC-based composite, however, shows a partial penetration of the polymer in the MOF first pore layer, hinting a slightly higher affinity between the MOF and the polymer. These results suggest that even when considering MOFs surfaces with drastically different morphologies, finding a highly compatible MOF/polymer pair for rigid polymers remains challenging.