Strong, Ductile MOF-Poly(urethane urea) Composites

Abstract

Metal-organic framework (MOF)-polymer hybrid materials have been investigated for use in personal protective equipment (PPE) for combating chemical threats. However, few of these composite materials have demonstrated the desired processability or balance of strength and ductility suitable for modern textiles. In this work, a poly(urethane urea) (PUU) polymer was synthesized to mimic solution-processable spandex for MOF composites that have combined advantages for both the force the composite can withstand (strength) and the ability of the material to deform under strain (ductility). UiO-66/PUU mixed matrix membranes (MMMs) with up to 50 wt % UiO-66 MOF showed both high strength and ductility. UiO-66 and UiO-66-NH2 MMMs with PUU mechanically outperformed previously studied 50 wt % MOF/poly(vinylidene difluoride) (PVDF) MMMs. Testing of MMMs against the chemical warfare agent simulant dimethyl-4-nitrophenylphosphate (DMNP) revealed that the polymer plays an important role, with UiO-66-NH2/PUU MMM showing the fastest hydrolysis rate. Ductile fibers of 50 wt % UiO-66 and UiO-66-NH2 PUU composites were successfully prepared and showed remarkable handling properties and activity toward DMNP hydrolysis with 50 wt % UiO-66-NH2/PUU fibers performing better than any of the MMMs tested. These MOF-polymer composites could also be electrospun into nanofiber mats, which further illustrates the diverse range of processing techniques available for these materials.