Role of MOF surface defects on the microscopic structure of MOF/polymer interfaces: A computational study of the ZIF-8/PIMs systems

- Molecular Dynamics coupled with quantum calculations to model MOF/polymer interfaces.
- Prediction of the interactions between MOFs and polymers at the interfaces.
- Understanding of the compatibility between MOF and polymers in the presence of defects at the MOF surface.

The influence of defects at the metal-organic framework (MOF) surface on the microscopic structure of a MOF/polymer composite has been studied by a computational methodology that combines density functional theory calculations with force field-based molecular dynamics simulations. This has been applied to composites formed by ZIF-8 and two different polymers of intrinsic microporosity: PIM-1 and PIM-EA-TB. Analysis of the MOF/polymer interactions, surface coverage, polymer conformation/stiffness and a full characterization of the interfacial voids are provided. We found that, although the nature of the MOF/polymer interactions changes in the presence of defects, the coverage and conformation of the polymer as well as the morphology of the “interfacial microvoids” remain practically unchanged from a microscopic point of view. These results suggest that there is no microscopic evidence that defective MOF surfaces drastically change the geometry of the MOF/polymer interface and the strength of the physisorption-type interactions in play.

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