Mechanism of Water Intrusion into Flexible ZIF-8: Liquid Is Not Vapor

• Published in: Nano letters 2023-06, Vol.23 (12), p.5430-5436
• Main Authors: Amayuelas, Eder, Tortora, Marco, Bartolomé, Luis, Littlefair, Josh David, Paulo, Gonçalo, Le Donne, Andrea, Trump, Benjamin, Yakovenko, Andrey Andreevich, Chorążewski, Mirosław, Giacomello, Alberto, Zajdel, Paweł, Meloni, Simone, Grosu, Yaroslav
• Format: Article
• Language: English
• Subjects: hydrophobic surfaces; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; intrusion mechanism; Letter; MOFs; molecular dynamics; synchrotron radiation
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.3c00235

Zeolitic Imidazolate Frameworks (ZIF) find application in storage and dissipation of mechanical energy. Their distinctive properties linked to their (sub)­nanometer size and hydrophobicity allow for water intrusion only under high hydrostatic pressure. Here we focus on the popular ZIF-8 material investigating the intrusion mechanism in its nanoscale cages, which is the key to its rational exploitation in target applications. In this work, we used a joint experimental/theoretical approach combining in operando synchrotron experiments during high-pressure intrusion experiments, molecular dynamics simulations, and stochastic models to reveal that water intrusion into ZIF-8 occurs by a cascade filling of connected cages rather than a condensation process as previously assumed. The reported results allowed us to establish structure/function relations in this prototypical microporous material, representing an important step to devise design rules to synthesize porous media.