Liberation of small molecules in polyimide membrane formation: An effect on gas separation properties

Synthesis and Properties of Cyclopentyl Cardo-Type Polyimides Based on Dicyclopentadiene

“…The cardo-type PIs in this study exhibited reasonably good tensile strength and elongation at break. These tensile properties are comparable to those of PIs reported in literatures [11][12][13]41]. Moreover, all the cardo PIs exhibited large elongation at break in the range of 16%-27%.…”

“…CPI-PM exhibited continuous and porous-free polymeric layer under 50,000× magnitude, whereas CPI-6F exhibited a porous-like morphology. The morphologies of these PIs were similar to those of dense PIs such as Matrimid [44], or crosslinked PI [41]. Consequently, specific voids were not easy to observe when compared with MOF based PIs [45,46] or PIM PIs [44,47].…”

Enhanced CO2 separation performance for tertiary amine‐silica membranes via thermally induced local liberation of CH3Cl

“…Membrane QA-180 demonstrated the smallest estimated mean effective pore size of 0.39 nm, whereas membranes QA-180-250 and QA-250 exhibited similar pore sizes (0.49-0.51 nm), which are comparable to, or slightly larger than, the TA-250 membrane (0.47 nm). These estimated mean effective pore sizes are consistent with the He/N 2 selectivity trend of these membranes at high temperatures, as shown in Table 5, where QA-180 (53) membranes showed much higher values in He/N 2 selectivity than the other membranes, the values of which were similar (23)(24)(25). This suggests that the liberation effect of CH 3 Cl molecules as well as a higher calcination temperature resulted in an impressive [Color figure can be viewed at wileyonlinelibrary.com] Figure 12.…”

“…Recently, some important attempts for processing ultramicroporous membranes that demonstrate high levels of gas permeance have included the use of polymers with intrinsic microporosity (PIM) [18][19][20][21] and thermally rearranged polymers (TR polymers), 22 high-temperature pyrolysis of polymeric membranes (the so-called carbon molecular sieving membranes), and lowtemperature thermal liberation of small molecules in block or graft copolymers. [23][24][25] Okamoto et al (2005) reported a lowtemperature pyrolysis method to produce a flexible pyrolytic membrane using sulfonated polyimides. 24 During relatively lower-temperature (4508C, under a nitrogen atmosphere) pyrolysis, the -SO 3 H groups decompose and create microvoids, which results in higher permeability for C 3 H 6 and higher permselectivity for C 3 H 6 /C 3 H 8 .…”

RETRACTED: Surface modification of TiO2 nanoparticles with biodegradable nanocellolose and synthesis of novel polyimide/cellulose/TiO2 membrane

“…However, the trade-off between gas permeability and selectivity exists as an objective for the study of membranes [18]. Many efforts have been done to enhance the permeability and selectivity of polymeric membranes [19], [20], [21], [22], [23], [24], [25], [26]. One method is to fabricate mixed matrix membranes or nanocomposite (NC) membranes.…”