DelRe Christopher, Hong Hyukhun, Wenny Malia B, Erdosy Daniel P, Cho Joy, Lee Byeongdu, Mason Jarad A
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States.
X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States.
J Am Chem Soc. 2023 Sep 13;145(36):19982-19988. doi: 10.1021/jacs.3c06627. Epub 2023 Sep 1.
Aqueous dispersions of microporous nanocrystals with dry, gas-accessible pores─referred to as "microporous water"─enable high densities of gas molecules to be transported through water. For many applications of microporous water, generalizable strategies are required to functionalize the external surface of microporous particles to control their dispersibility, stability, and interactions with other solution-phase components─including catalysts, proteins, and cells─while retaining as much of their internal pore volume as possible. Here, we establish design principles for the noncovalent surface functionalization of hydrophobic metal-organic frameworks with amphiphilic polymers that render the particles dispersible in water and enhance their hydrolytic stability. Specifically, we show that block co-polymers with persistence lengths that exceed the micropore aperture size of zeolitic imidazolate frameworks (ZIFs) can dramatically enhance ZIF particle dispersibility and stability while preserving porosity and >80% of the theoretical O carrying capacity. Moreover, enhancements in hydrolytic stability are greatest when the polymer can form strong bonds to exposed metal sites on the external particle surface. More broadly, our insights provide guidelines for controlling the interface between polymers and metal-organic framework particles in aqueous environments to augment the properties of microporous water.
具有干燥、可通气孔隙的微孔纳米晶体的水分散体——被称为“微孔水”——能使高密度的气体分子通过水进行传输。对于微孔水的许多应用而言，需要通用策略来对微孔颗粒的外表面进行功能化，以控制其分散性、稳定性以及与其他溶液相成分（包括催化剂、蛋白质和细胞）的相互作用，同时尽可能保留其内部孔隙体积。在此，我们确立了用两亲聚合物对疏水金属有机框架进行非共价表面功能化的设计原则，这些聚合物能使颗粒分散于水中并增强其水解稳定性。具体而言，我们表明，持久长度超过沸石咪唑酯框架（ZIFs）微孔孔径大小的嵌段共聚物，能显著提高ZIF颗粒的分散性和稳定性，同时保留孔隙率以及超过80%的理论载氧能力。此外，当聚合物能与颗粒外表面暴露的金属位点形成强键时，水解稳定性的增强最为显著。更广泛地说，我们的见解为控制水性环境中聚合物与金属有机框架颗粒之间的界面提供了指导，以增强微孔水的性能。
