Relationship between gas transport properties and fractional free volume determined from dielectric constant in polyimide films containing the hexafluoroisopropylidene group

Polyimides (PIs) with single phenyl pendant substitution were prepared based on three diamines containing phenyl pendant group, namely, 2,5-bis(4-aminophenoxy) biphenyl, 2-phenyl-4,4′-diaminodiphenyl ether, and 2,5-diaminobiphenyl (p-PDA), with the dianhydride component of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride, respectively. The physical properties of the membranes were examined, including thermal properties, fractional free volume ( FFV), solubility, and morphological structures, and were compared with the analogues without phenyl pendant. Gas transport properties of the membranes were investigated and discussed from the viewpoint of structure–property relationship. For 6FDA-derived PI membranes, gas permeability increased as the degree of PI backbone rigidity leveled up. Gas transport properties were not improved by the incorporation of phenyl pendant group for 6FDA type containing ether linkage and marginally improved as compared between PI (6FDA/p-PDA) and PI (6FDA/p-phenylenediamine (PDA)). To increase the phenyl substitution density of 6FDA/PDA-type backbone, a novel diamine bearing two phenyl pendant groups, that is, 2,6-diphenyl-1,4-diaminobenzene (p, p′-PDA) was synthesized, and PI derived from 6FDA and p, p′-PDA was prepared. The gas permeability coefficients of PI (6FDA/p, p′-PDA) were remarkably larger than those of PI (6FDA/p-PDA) and PI (6FDA/PDA).

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Perfluoropolymer/Molecular Sieve Mixed-Matrix Membranes

Membranes ◽

10.3390/membranes9020019 ◽

2019 ◽

Vol 9 (2) ◽

pp. 19 ◽

Cited By ~ 4

Author(s):

Gianni Golemme ◽

Anna Santaniello

Keyword(s):

Transport Properties ◽

Molecular Sieves ◽

Gas Transport ◽

Maxwell Model ◽

Mixed Matrix Membranes ◽

Mixed Matrix ◽

Fractional Free Volume ◽

Phase Approach ◽

Gas Transport Properties ◽

Matrix Membranes

Despite the outstanding chemical, thermal and transport properties of amorphous and glassy perfluorinated polymers, only few works exist on the preparation and transport properties of perfluoropolymer/molecular sieves mixed-matrix membranes (MMMs), probably because of their poor compatibility. In this review, the compatibilization of ceramic molecular sieves with perfluorinated matrices is considered first, examining the effect of the surface treatment on the gas transport properties of the filler. Then the preparation of the defect-free hybrid membranes and their gas separation capabilities are described. Finally, recent modelling of the gas transport properties of the perfluoropolymer MMMs is reviewed. The systematic use of molecular sieves of different size and shape, either permeable or impermeable, and the calculation of the bulk transport properties of the molecular sieves—i.e., the unrestricted diffusion and permeability—allow to understand the nature of the physical phenomena at work in the MMMs, that is the larger the perfluoropolymer fractional free volume at the interface, and restricted diffusion at the molecular sieves. This knowledge led to the formulation of a new four-phase approach for the modelling of gas transport. The four-phase approach was implemented in the frame of the Maxwell model and also for the finite element simulation. The four-phase approach is a convenient representation of the transport in MMMs when more than one single interfacial effect is present.

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Gas transport properties of high free volume polyarylates based on isophthalic/terephthalic acid chloride mixtures

Journal of Membrane Science ◽

10.1016/j.memsci.2007.08.026 ◽

2007 ◽

Vol 305 (1-2) ◽

pp. 347-352 ◽

Cited By ~ 9

Author(s):

M.T. Guzmán-Gutierrez ◽

F.A. Ruiz-Treviño ◽

M. Zolutukhin ◽

S. Hernández-López ◽

U. Scherf

Keyword(s):

Transport Properties ◽

Free Volume ◽

Acid Chloride ◽

Terephthalic Acid ◽

Gas Transport ◽

Gas Transport Properties

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Synthesis and gas transport properties of novel poly(ether ether ketone)s containing fluorene group

High Performance Polymers ◽

10.1177/0954008319832956 ◽

2019 ◽

Vol 31 (9-10) ◽

pp. 1173-1182 ◽

Cited By ~ 2

Author(s):

Yayun Zheng ◽

Xing Yang ◽

Meng Yuan ◽

Jujie Luo

Keyword(s):

Transport Properties ◽

Free Volume ◽

Gas Transport ◽

Gas Permeability ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Gas Transport Properties ◽

Ether Ether Ketone ◽

Poly Ether Ether Ketone ◽

Ether Ketone

Two novel gas separation membranes (Phenyl(Ph)-poly(ether ether ketone)s (PEEKs) and PEEKs) based on PEEKs with a high fractional free volume were designed and synthesized. The structure and thermodynamic stability of the membranes were investigated using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. The two membranes, which were determined to be high-molecular weight polymers by gel permeation chromatography, showed good solubility in a weakly polar solvent. The gas transport properties of the Ph-PEEK membranes were investigated for different gases (CO2, O2, CH4, and N2) at 25°C and 1 atm. The Ph-PEEK-3 membrane with the largest free volume had the largest gas permeability coefficient and maintained good selectivity. The effect of operating temperature on the gas permeation of the Ph-PEEK-3 membrane was also investigated, and the maximum permeability of the four single gases was reached at 55°C and 1 atm.

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