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In the present study, graphene oxide (GO) was incorporated into poly(vinylidene fluoride) (PVDF) and chemically modified PVDF (M-PVDF) to prepare mixed matrix membranes (MMMs) for gas separation application. Performed analyses proved appropriate dispersion of exfoliated GO sheets in polymer matrices and sufficient compatibility at the interfacial phases. M-PVDF based MMMs were thermally and mechanically more stable relative to the PVDF-based MMMs. The oxygen containing functional groups in M-PVDF was probably the main reason for this more stability. PVDF/GO MMMs rendered low gas permeability and high selectivity. Both impermeable GO sheets and crystalline phases of PVDF were responsible for such behavior. On the other hand, interestingly gas permeability of M-PVDF/GO MMMs was enhanced while no substantial decline was recorded in gas selectivity. For instance, He and CO 2 permeability was increased 12.46% and 25.89%, respectively, compared to the pure PVDF membrane. This behavior originated from functional groups of M-PVDF and the interaction of these groups with GO sheets. Since GO often amplified gas barrier properties of polymers, such increscent would be appreciable.

In this study, poly­(vinylidene fluoride) (PVDF) was modified by a mixture of KOH and KMNO4 in order to effect HF elimination. During this reaction, some functional groups were created in the PVDF structure. The metal–organic frameworks, MIL-53­(Al) and NH2-MIL-35­(Al), were embedded in modified PVDF (M-PVDF) to fabricate mixed matrix membranes (MMMs). Different characterization techniques such as FT-IR, XRD, SEM, DSC, TGA, and contact angle tests have been implemented to identify the prepared membranes. Pure and mixed (1:1) CO2 and CH4 were used to test gas separation performance of MMMs. CO2 permeance was increased for pure M-PVDF membrane compared with the pristine PVDF by 31.2%. Upon 10 wt % loading of MIL-53­(Al) and NH2-MIL-35­(Al) in M-PVDF, CO2 permeability increased 104.33% and 80.02% relative to the unfilled M-PVDF. The highest CO2/CH4 ideal selectivity and separation factor of 43.9 and 42.65, respectively, were reported for NH2-MIL-35­(Al)/M-PVDF with 10 wt % loading. These improvements could be attributed to the breathing effect of MOFs, created polar moieties in PVDF through the modification, and hydrogen bonding interactions between the MOFs and the polymer.

A CuBTC (copper(ii) benzene-1,3,5-tricarboxylate) metal organic framework (MOF) and graphene oxide (GO) nanosheets were introduced into a semi-crystalline PVDF to produce mixed matrix membranes (MMMs) to promote gas separation performance.

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