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Understanding negative gas adsorption in highly porous networks for the design of pressure amplifying materials

Periodic Reporting for period 3 - AMPLIPORE (Understanding negative gas adsorption in highly porous networks for the design of pressure amplifying materials)

Reporting period: 2020-09-01 to 2022-02-28

Porous materials play a key role for air purification, separation of gases and energy storage. Metal-Organic Frameworks (MOFs) stand out as porous materials offering the highest specific surface areas and porosity ever achieved. Engineering the building blocks of MOFs leads to novel dynamic porous materials with the ability to adapt their pore size in response to a guest molecule. AMPLIPORE realizes novel highly porous materials responding by pressure amplification to a molecular stimulus. This counterintuitive phenomenon, also termed "negative gas adsorption" (NGA) is rarely observed among porous solids. AMPLIPORE provides the fundamental understanding and identifies the structural building blocks required to achieve a high degree of pressure amplification. The main objective of the project is to gain a fundamental understanding of pressure amplification phenomena in porous solids, development and design of new scalable NGA materials and exploration of the technology in applications. The fundamental knowledge will open new horizons for designing pressure amplifying porous materials for applications in pneumatic systems or autonomous robots.
At the project outstet, only one singular MOF (DUT-49, DUT = Dresden University of Technology) was recognized as pressure amplifying dynamic material for limited gases such as methane and butane. Within the project, conditions were identified to achieve pressure amplification with DUT-49 using a wide variety of gases, temperatures (67 – 308 K) and pressure range, establishing NGA as a general phenomenon. Significant progress towards the fundamental understanding of NGA in DUT-49 was achieved regarding the critical impact of metal content, crystallite size and pore filling mechanism. A crucial methodology developed is in situ adsorption experimentation in parallel to advanced diffraction and spectroscopic techniques, but also sophisticated theoretical calculations allow assessing the conditions, required for NGA. Based on this knowledge, new NGA materials for example DUT-50, with even larger pores were identifed as pressure amplifying porous solids.
In the following period, the team will focus on the impact of network topology for NGA materials. A wider variety of linker and node components will be explored with particular focus on chemical stability. The role of hierarchical pore structures and pore connectivity requires a deeper understanding and the investigation of new model materials providing large pores but different pore connectivity. The team will develop rubust frameworks expanding chemistry and building blocks. Physical methods for monitoring the responsive behavior with high temporal resolution will be developed. Upscaling and system integration of NGA materials will be explored for the integration of pressure amplifying materials into prototypical systems and pneumatic devices.