Gas‐sorption properties of 6FDA–durene/1,4‐phenylenediamine (pPDA) and 6FDA–durene/1,3‐phenylenediamine (mPDA) copolyimides

Abstract

ABSTRACT:We investigated the sorption isotherms of O 2 , N 2 , CH 4 , and CO 2 gases in 6FDA-durene, 6FDA-1,4-phenylenediamine (6FDA-pPDA), and 6FDA-1,3-phenylenediamine (6FDA-mPDA) homopolymers and 6FDA-durene/pPDA and 6FDA-durene/mPDA copolyimides. The solubilities decrease in the order of the inherent condensabilities of the penetrant gases, namely, CO 2 , CH 4 , O 2 , and N 2 . The chemical structures of the polymer, as well as the chain packing, determine the sorption properties of these homopolymers and copolymers. The FDA-durene homopolymer has the highest solubility for all gases because of its high specific free volume and fractional free volume. The solubilities of the copolymers increase with an increasing 6FDA-durene content, while the solubility selectivities of the copolymers only vary slightly. The values of K D (Henry's law constant) and C H Ј (Langmuir site capacity) of these copolyimides decrease with a decreasing 6FDA-durene content. To our surprise, contradictory to the previous known fact that the meta-connected materials tend to have denser molecular packing than that of the para-linked materials for homopolymers, the 6FDA-durene/mPDA 80/20 copolymer has higher gas solubilities than those of the 6FDA-durene/ pPDA 80/20 copolymer. The random moiety sequence within the copolymer may be the main cause for the abnormal phenomenon.

Using iron (III) acetylacetonate as both a cross-linker and micropore former to develop polyimide membranes with enhanced gas separation performance

“…One glassy polymer of interest is polyimide containing 4,4 -(hexafluoroisopropylidene) diphthalic anhydride (6FDA) [8][9][10][11][12][13][14][15][16]. It consists of bulky CF 3 groups that reduce chain packing and increase chain stiffness due to steric hindrance.…”

Microporous Organic Polymers for Methane Storage

“…The maximum gravimetric CH 4 uptake observed under these conditions was 5.2 mmol g À1 (116 cm 3 g À1 STP) at 20 bar/298 K -much higher than partially fluorinated polyimides studied previously. [8] The BCMBP powder (sample 1) ) of the samples studied (Table 1). This material also shows the highest H 2 uptake reported so far for an amorphous organic polymer at 15 bar (Fig.…”

“…42 cm 3 ; standard temperature and pressure (STP) at 25 bar/296 K). [8] Natural gas, which consists mostly of methane, is available in large quantities and is environmentally preferable to other hydrocarbon fuels because of its cleaner combustion. However, for large-scale use it is necessary to store methane in a safe and economical way.…”

Hyper-crosslinked, hybrid membranes via interfacial polymerization

“…The high CO 2 uptake, also observed for 6FDA based polymers, is attributed to the presence of CF 3 groups in the structure. 10,64,65 The data from Wind et al for an ester modified 6FDA-DAM:DABA-based polyimide has a similar order of magnitude CO 2 concentration. The magnitude of CO 2 uptake increases with a decreasing concentration of the POSS solution used for the synthesis.…”

“…Particularly in membrane science and composite materials science, the combination of inorganic particles in a polymer matrix is regularly denoted as "hybrid". [62][63][64][65][66] Although such materials do combine two constituents in one material, the physical properties will in general be in between those of the two individual constituents. Examples of this class include polymer modification by dispersing polyhedral oligomeric silsesquioxanes (POSS), 67,68 zeolite, 69 or silica [70][71][72] particles in the polymeric phase during processing.…”