(384a) Understanding Flow Coating Based Large Area MOF Thin Films Formation Using in-Situ Scattering Techniques

Porous coordination polymers, including metal-organic frameworks, hold incredible potential to impact numerous technologies. The wide breath of applications include charge and ion transport membranes, separation membranes, hydrogen and natural gas storage, drug delivery, sensors, ‘self-cleaning’ surfaces, etc. However, the current technological impact of these materials is muted due to the lack of understanding of fundamental theories behind MOF crystallization and thin film formation. Many potential applications require MOFs to be created as thin films, such as membranes for batteries and fuel cells, separation membranes etc., since increased thickness creates barriers to mass and charge transfer.

We will show that the investigation of MOF crystallization, guided by a combination of chemistry, fluid dynamics, and crystallization theories, will allow us to discover new design rules to create rapid, uniform and high quality thin films. Using evaporative crystallization during flow coating, large area, pinhole free thin films of multiple prototypical MOFs can be created. In addition, the use of nucleation zones can be utilized to control the placement and patterning of HKUST-1 and UiO-66 is possible. Finally, a combination of in-situ grazing incidence X-ray scattering and diffraction combined with reaction kinetics modelling will be used to explain the intricacies of MOF thin film crystallization during flow coating. We show that MOF thin film nucleation occurs in two steps, first with the formation of an amorphous scattering cluster which is then followed by the crystallization as a thin film.