Polymer-nanofiller Compatibilization in Mixed Matrix Membranes for advanced gas separation (COM3)

In mixed matrix membranes (MMMs) the ease of formation of polymeric membranes combines with the outstanding separation properties of suitable fillers (MOFs, zeolites, COFs, activated carbons, porous polymers, 0D-, 1D- and 2D-materials, etc.), improving at the same time both the permeability and the selectivity of the polymers. Unfortunately, the compatibility is often a relevant problem, especially when the glassy polymer does not have any chemical affinity with the filler, resulting in poor adhesion, gaps between the phases and consequent losses in selectivity. MMMs made of Polymer of Intrinsic Microporosity-1 (PIM-1) and ZIF-8 is such an example of poor compatibility. Amorphous, glassy and hydrophobic perfluoropolymers (PFPs: several grades of Teflon AF, Hyflon AD, …) are even more “difficult” matrices for MMMs, as anybody understands when adhesive tape does not stick on PTFE. The goal of COM3 is the development of new concepts and strategies to adhere the filler on polymer in gas separation MMMs, in order to match the best polymer with the best filler even when the pristine ingredients are not compatible. PIM-1 and PFPs membranes, thoroughly characterized in the last 20-30 years, display outstanding physico-chemical and transport properties for industrially relevant separations (e.g. O2/N2, CO2/CH4, CO2/N2, olefins/alkanes, H2/CH4, He/CH4, etc.). For this reason, PIM-1 and PFPs represent ideal matrices for testing the new compatibilization concepts to be developed. Despite the tremendous potential advantages of MOF/PFP MMMs, to date no example of such MMMs has been reported in the open literature, and only UniCAL successfully dispersed zeolitic materials in both PIM-1 and PFPs. COM3 is aimed at filling such gaps. Layered zirconium phosphates and phosphonates (ZrPs) are ideal 2D fillers since their chemistry is well known and they can be easily synthesized, exfoliated and functionalized in countless different fashions. In a similar way, 3D fillers like MOFs, zeolites and SAPOs are also well known and characterized for gas transport, amenable to be derivatized and therefore suitable for testing the new concepts. Based on UniCAL experience on defect-free and selective PIM-1 and PFP MMMs, UniPO and UniCAL will prepare and derivatize ZIF-8 and SAPO-34, whereas UniPG will prepare functionalized ZrPs. Such fillers will be used for new PIM-1 and PFP MMMs. Morphology, free volume, gas permeability, solubility and diffusion, aging, evolution of mobility of filler and polymer moieties, in the pure phases and in the MMMs, will be extensively studied with a combination of different techniques (XRD, sorption porometry, MAS NMR, IR, Raman, SEM, TEM, EDX, modelling, etc.) to improve adhesion, stability and selectivity of the MMMs. COM3 will strengthen the already existing complementary scientific collaborations among UniPO, UniPG and UniCAL, opening new unexplored research areas for MMMs with important applicative fallouts.