Mixed Matrix Membranes Loaded with a Porous Organic Polymer Having Bipyridine Moieties

Abstract

Mixed matrix membranes (MMMs), derived from three aromatic polyimides (PIs), and an affordable porous organic polymer (POP) having basic bipyridine moieties were prepared. Matrimid and two fluorinated polyimides, which were derived from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride and 2,2′-bis(4-aminophenyl)hexafluoropropane (6F6F) or 2,4,6-trimethyl-m-phenylenediamine (6FTMPD), were employed as polymer matrixes. The used POP was a highly microporous material (surface area of 805 m2 g−1) with excellent thermal and chemical stability. The MMMs showed good compatibility between the PIs and POP, high thermal stabilities and glass transition temperatures superior to those of the neat PI membranes, and good mechanical properties. The addition of POP to the matrix led to an increase in the gas diffusivity and, thus, in permeability, which was associated with an increase in the fractional free volume of MMMs. The increase in permeability was higher for the less permeable matrix. For example, at 30 wt.% of POP, the permeability to CO2 and CH4 of the MMMs increased by 4- and 7-fold for Matrimid and 3- and 4-fold for 6FTMPD. The highest CH4 permeability led to a decrease in CO2/CH4 selectivity. The CO2/N2 separation performance was interesting, as the selectivity remained practically constant. Finally, the POP showed no molecular sieving effect towards the C2H4/C2H6 and C3H6/C3H8 gas pairs, but the permeability increased by about 4-fold and the selectivity was close to that of the matrix. In addition, because the POP can form metal ion bipyridine complexes, modified POP-based MMMs could be employed for olefin/paraffin separations.

Recent Advances in Membrane-Based Biogas and Biohydrogen Upgrading

“…However, a considerable number of glassy polymers are being employed as continuous phase in MMMs such as cellulose acetate (CA), polyimide (PI), polysulfone (PSU), polyamide (PA), polypropylene (PP), polyethersulfone (PES), poly-vinylidene fluoride (PVDF) and perfluorinated materials, etc. [95,97,[113][114][115][116]. Polymers such as PMP (4-methyl-2-pentyne), PTBA (tert-butylacetylene) and PTMSP (1-trimethylsilyl-1-propyne), namely "reverse-selective polymers", have also been used as continuous phase due to their high fractional free volume.…”

Microporous Polymeric Networks Containing a Long-Term Stable AuI Catalyst for Enyne Cyclization

“…14−20 Contrary to MOFs and COFs, which are crystalline, POPs are amorphous materials, which results in a wider distribution of the pore size. In this context, POPs have gained attention in many applications such as gas storage, 21 separation, 22 and catalysis 23 due to their high specific surface areas, tunable pore size, and easy functionalization. 16,23 Recently, our group has developed a low-cost methodology for preparing POPs by polycondensation reactions made by electrophilic aromatic substitution (EAS) between a ketone presenting electron-withdrawing groups and trifunctional rigid aromatic monomers.…”

“…A wide variety of materials have been employed as heterogeneous catalysts, such as zeolites, polymeric resins, , oxides, − silicas, − metal–organic frameworks (MOFs), , covalent–organic frameworks (COFs), , or porous organic polymers (POPs). − Contrary to MOFs and COFs, which are crystalline, POPs are amorphous materials, which results in a wider distribution of the pore size. In this context, POPs have gained attention in many applications such as gas storage, separation, and catalysis due to their high specific surface areas, tunable pore size, and easy functionalization. , Recently, our group has developed a low-cost methodology for preparing POPs by polycondensation reactions made by electrophilic aromatic substitution (EAS) between a ketone presenting electron-withdrawing groups and trifunctional rigid aromatic monomers. The resulting POPs presented high microporosity, with Brunauer–Emmett–Teller (BET) surface areas of up to 800 m 2 g –1 , and outstanding thermal stability (superior to 450 °C) .…”

Basic Alkylamine Functionalized PAF‐1 Hybrid Membrane with High Compatibility for Superior CO2 Separation from Flue Gas

“…[14] In this regard, some PAFs were embarked to be synthesized and processed into MMMs for CO 2 /N 2 separation. [15][16][17][18][19][20][21][22][23][24][25] However, most membranes still confronted the selectivity-permeability tradeoff, [15][16][17][18][19][20][21][22][23] impeding their practical application of separating low-concentration CO 2 from N 2 (e.g., flue gas). To realize the target separation performance, functional PAFs that enable MMMs with molecular-level homogeneity are highly desirable.…”