Metal-organic cages (MOCs) are discrete coordination cages composed of metal ions connected by organic ligands. The modularity and inherent porosity of MOCs make them attractive materials for applications in gas storage and separation, though they often suffer from a lack of processability. We, therefore, sought to develop a hybrid polymer-MOC (polyMOC) material with accessible permanent porosity that could enable more favorable mechanical properties. We utilized a Radical Addition-Fragmentation Transfer (RAFT) polymerization due to its ability to control the molecular weight and polydispersity of chains, which permits the synthesis of block copolymers and polymers with more complex architectures. We developed a procedure using a RAFT polymer ligand, free isophthalic acid, and copper (II) nitrate trihydrate to form novel polymer-Cu₂₄(m-bdc)₂₄ cage hybrids. The crystallinity of the polymers was measured via PXRD, and we determined that simply varying ratios of free ligand to polymer-bound ligand provided a facile method for tuning the crystallinity of the polymers. ¹H NMR of digested materials and IR spectroscopy further confirmed the successful incorporation of the polymer ligand in the material, which was verified according to the stoichiometric ratios implemented during synthesis. Atomic Force Microscopy (AFM) will be used to compare the morphology of the polymer-Cu₂₄(m-bdc)₂₄ cage hybrids. This research lays a foundation for the development of bulk copper and rhodium polyMOC materials, including the addition of multiple polymer blocks for processable polyMOC materials for future applications in gas storage and separation.

Matthew Pearson

Massachusetts Institute of Technology

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