3D printed ABS-MOF composite materials and their gas storage properties

Abstract

Metal organic framework materials (MOFs) have been primarily recognized for their ability to promote selective storage of gas molecules. In their as-synthesized (powdered) form, MOFs are not easily processed for use in end-devices where their properties are to be exploited. We have produced composites in which either ZIF-8 or HKUST-1 have been incorporated into acrylonitrile butadiene styrene (ABS). These composites were then 3D printed using a conventional, commercially available 3D printer. Although many MOFs suffer from instability in humid environments, each of the MOF’s in our study maintains its structure within the ABS composite even upon soaking in water. Moreover, the MOFs maintain their nitrogen adsorption capacities within the composites. Spectroscopic, thermophysical analysis, gas adsorption isotherms, and gas adsorption and desorption studies for ABS-ZIF-8 composites reveal an ideal system that behaves as a 9:1 linear combination of ABS and ZIF-8. The same analysis for ABS-HKUST-1, however, reveals a more complex system where the composite significantly reduced gas adsorption capacity at 77 K and slower adsorption and desorption profiles at room temperature. Our thermo-physical analysis indicates that these changes are likely due to the HKUST-1 altering the structural and, therefore, gas adsorption and diffusion properties of the ABS by inducing stronger polymer-polymer interactions. Nonetheless, at room temperature the HKUST-1 composite displays a higher nitrogen adsorption capacity than the ZIF-8 composite. The retention of MOF gas adsorption properties within the composite is promising in that these materials can be optimized (MOF, polymer, and 3D printed geometry) for a number of applications including gas storage, filtering, sensing, and catalysis.