Uniform Growth of Nanocrystalline ZIF-8 on Cellulose Nanocrystals: Useful Template for Microporous Organic Polymers

Zeolitic imidazolate framework (ZIF-8) nanocrystals were uniformly grown on the surface of cellulose nanocrystals (CNCs) to give a hybrid material, ZIF@CNCs. By varying the stoichiometry of the components, it was possible to control the size of the ZIF-8 crystals grown on the CNC surface. Optimized ZIF@CNC (ZIF@CNC-2) was used as a template to synthesize a microporous organic polymer (MOP), ZIF@MOP@CNC. After etching the ZIF-8 with 6 M HCl solution, a MOP material with encapsulated CNCs (MOP@CNC) was formed. Zinc coordination into the porphyrin unit of the MOP yielded the ship-in-a-bottle structure, Zn MOP@CNC, comprised of CNCs encapsulated within the Zn-MOP. In comparison to ZIF@CNC-2, Zn MOP@CNC showed better catalytic activity and chemical stability for CO2 fixation, converting epichlorohydrin to chloroethylene carbonate. This work demonstrates a novel approach to create porous materials through CNC templating.