A Physical Entangling Strategy for Simultaneous Interior and Exterior Modification of Metal-Organic Framework with Polymers

A new strategy uses a common feature of metal-organic frameworks (MOFs), namely porosity rather than functionality, to achieve simultaneous interior and exterior modification of a MOF with polymers. We demonstrate that an anhydride-terminated polyimide oligomer can be covalently grafted to the amine-functionalized methacrylate polymer backbone residing underneath the MOF surface and physically entangled within the 3D nanochannels. The MOF particles were evenly coated with a thin layer of polyimide brushes on the surface thereby exhibiting increased dispersibility in solvent media as well as in polymer matrix. The MOF pores were decorated with aliphatic amine groups to endow the MOF with higher CO2 affinity at low pressure. The polyimide-grafted surface allowed MOF particles to interact favorably with the polyimide matrix, producing defect-free MMM with drastically improved CO2 permeability and maintaining the inherent CO2/N-2 and CO2/CH4 selectivity of the neat polymeric membrane.