Facile in Situ Polymer Functionalization Approach for Constructing Water-Resistant Metal–Organic Frameworks

Metal–organic frameworks (MOFs) have been widely investigated for their use in separation, such as gas adsorption or biotechnology. However, numerous MOFs are unstable in aqueous environment or humid conditions, significantly hindering their practical application. While current methods for enhancing MOF water stability can largely decrease the pore structural parameters, herein, we proposed a strategy of in situ trace polymer functionalization for enhancing the MOF stability and demonstrated that the water stability of four common MOFs can be enhanced greatly by incorporating hydrophobic PSfCOOH molecules into the framework through a one-step synthesis. A series of investigations into the local chemical structure and bonding environment suggest that the enhanced water stability arises from the construction of hydrophobic microenvironments and the steric hindrance around the metal sites. The prepared Cu-BTC-PSfCOOH remained intact after being immersed in water for even 10 days, preserving 90% of its original pore structural parameter, such as Brunauer–Emmett–Teller (BET) surface areas. Moreover, 88% of the initial BET surface areas can be maintained after one-day immersion in 6 M HCl solution. The strategy is also demonstrated to be efficient in enhancing the water stability of three other typical MOFs, showing good universality in constructing water-resistant MOFs.