Background

Metal Organic Frameworks (MOFs) have great potential in applications such as gas storage and separation, hydrogen fuel cells, catalysis, carbon capture and drug delivery / biomedical imaging. However handling and fabrication of MOF components can be a challenge as most MOFs exist in powder form and have to be either compressed into pellets, embedded in a polymer matrix or coated onto a scaffold structure. These approaches either require handling of nanoscale powders with the health and safety challenges this brings, additional manufacturing or processing steps or in the case of embedding in a polymer matrix loss of porosity / adsorbtion capacity. The University of Exeter’s technology addresses these challenges by combining MOF’s with 3D printable polymers in such a way that the majority of the MOF adsorbtion capacity is retained but with the benefit of being easily able to fabric complex structures with pore sizes ranging from the macro to nano scale.

Technology Overview

University of Exeter have developed a range of MOF‑polymer materials that can be used in additive manufacturing to produce complex structures. In these materials the MOF crystals are nucleated on the surface of the polymer granules preserving the inherent porosity of the MOFs. When the polymer granules are fused by selective laser sintering during additive manufacturing the MOF’s remain substantially on the surface of the polymer structure. The effectiveness of this technique has been demonstrated by nucleating ZIF‑67 on the surface of PA2200 (polyamide 12) and then 3D printing a porous cubic structure , . The even distribution and exposure of ZIF‑67 crystals on the surface can be seen in . The 3D printed porous structure was found to have a CO₂ adsorbtion capacity approximately 5x greater than alternative MOF‑polymer blends such as HKUST‑1/PA12 where the MOF is incorporated as a filler material. The fabrication technique has also been found to work for a range of polymer materials including polyaryletherketones (PAEKs) and polyoelfins as well as polyamides and with a range of different MOFs.

The technology is currently at TRL 3‑4 with proof of concept demonstrated in the laboratory. 3D MOF‑polymer materials have been manufactured at a kilogram scale but the methodology is easily scalable to production volumes.

Benefits

The key benefits of the technology are:

• Enables MOFs to benefit from the greater design flexibility of 3D printing without the loss of porosity / adsorbtion capacity resulting from physical blends / incorporation as a filler
• Improved health and safety through reduced nanoscale powder handling as the MOF crystals are strongly bound to the polymer surface
• Ability to directly fabricate complex 3D structures with functional surfaces without the need for subsequent surface treatment

Applications

The technology has the potential to be applied in a wide range of applications including:

• Gas storage & separation
• Carbon capture
• Hydrogen fuel cells
• Catalyst supports
• Filtration

Opportunity

The University of Exeter intends to further explore the range of materials and applications that this technology can enable.

The University of Exeter believe these materials may be particularly suited to high value applications in the gas storage and separation, hydrogen fuel cell and filtration markets, and would welcome feedback about any challenges or unmet needs these sectors have.

The University of Exeter Ewould also be keen to understand any potential barriers to adoption of new materials and technologies within these markets.