2022 Annual Meeting
Meniscus Guided Coating and Evaporative Crystallization of Metal Organic Framework Thin Films
Thin-film fabrication of metal organic frameworks (MOFs) has been explored for a range of applications, including separations, catalysis, sensing, and charge transport. However, many fabrication techniques have obstacles, including slow crystallization, control over film thickness, and control over crystallinity. Recently, a meniscus-guided coating technique, called solution shearing, has been shown to create MOF thin films within minutes and with control over the film thickness. The solution-shearing process has multiple discrete and continuous parameters that can be varied, including the metal ion and linker concentrations, solvents, substrate temperature, coating speed, and the number of coating passes. In this work, we overview the various solution shearing investigations performed by the Giri Crystallization Lab at the University of Virginia. We show that solution shearing can rapidly produce continuous, large-area thin films of TCNQ@HKUST-1 and reduce the formation of grain boundaries better than pelletization, allowing for large-area electronics with both charge transport and porosity for applications as sensors and electronics. Additionally, we incorporate an active learning approach into the solution-sheared HKUST-1 thin-film-processing parameters to control the coverage and extend the approach to gain control over the thickness. We extend these principles to show that the highly stable zirconium MOF, UiO-66, can be formed using evaporative crystallization during solution shearing. This is the first instance of UiO-66 crystals being formed using an evaporative crystallization-based flow coating method, and solution shearing shows the promise to be applicable to form large area zirconium-based MOF crystals in a rapid manner. Finally, we explore the synthesis of Polymer-MOF composite films using solution shearing.