Gas permeation, diffusion, sorption and free volume of poly(2-trifluoromethyl-2-pentafluoroethyl-1,3-perfluorodioxole)

Белов, Н. А.; Nikiforov, R. Yu.; Полунин, Е. В.; Pogodina, Yu. E.; Заварзин, И. В.; Shantarovich, V. P.; Yampolskii, Yu. P.

doi:10.1016/j.memsci.2018.07.077

Cited by 30 publications

(14 citation statements)

References 42 publications

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“…In the last few years, other amorphous and glassy PFPs have been synthesized and studied for gas separation: atactic poly(hexafluoropropene) [ 27 ], new perfluoro-1,3-dioxoles [ 28 ], homo- and co-polymers of perfluoro(2-methylene-1,3-dioxolane)s ( Figure 2 ) [ 29 , 30 , 31 ]. The latter class of PFPs looks extremely interesting for the preparation of gas separation membranes, with impressive separation factors, beyond the 2008 Robeson upper bound for the H 2 /CH 4 , He/CH 4 , CO 2 /CH 4 , and N 2 /CH 4 separations [ 30 , 31 ].…”

Section: Introductionmentioning

confidence: 99%

Perfluoropolymer/Molecular Sieve Mixed-Matrix Membranes

Golemme

Santaniello

2019

Membranes

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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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Section: Introductionmentioning

confidence: 99%

Perfluoropolymer/Molecular Sieve Mixed-Matrix Membranes

Golemme

Santaniello

2019

Membranes

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“…To simplify the analysis, the micro‐cavities in the copolymers were assumed to be spherical, as reported in the other studies. The ortho‐positronium (o‐Ps) lifetime ( τ 3 and τ 4 ) which were related to free volume radius ( R ) were calculated with a semi‐empirical equation based on a spherical‐cavity model as follows 15,21,22 :

τ_{i} = 0.5 {[1 - \frac{R_{i}}{R_{i} + 1.66} + \frac{1}{2 π} \sin (\frac{2 π R_{i}}{R_{i} + 1.66})]}^{- 1}; i = 3, 4,

where τ i and corresponding R i were expressed in the units of ns and Å , respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Fang et al [11][12][13] prepared perfluoro-dioxolane copolymer membranes with tunable transport characteristics by adjusting the composition of the comonomer perfluoro-(2-methylene-1,3-dioxolane), which was considered to act as "selective enhancers" to improve polymer chain packing and selectivity of the membrane by the molecule size. Belov et al 14,15 reported poly(2-trifluoromethyl-2-pentafluoroethyl-1,-3-perfluorodioxole) was amorphous and it had high gas permeability.…”

Section: Introductionmentioning

confidence: 99%

Free volume characteristics of 2,2‐bistrifluoromethyl‐4,5‐difluoro‐1,3‐dioxole‐co‐tetrafluoroethylene copolymers: Effect of composition and molecular weight

Mao

Cai

et al. 2021

Journal of Polymer Science

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2,2‐bistrifluoromethyl‐4,5‐difluoro‐1,3‐dioxole‐co‐tetrafluoroethylene (PDD‐TFE) copolymer is a good candidate to prepare gas separation membranes with excellent permeability due to its free volume characteristics. However, the influence of PDD‐TFE copolymer structure on its free volume characteristics is less studied. In this paper, PDD‐TFE copolymers with different compositions and molecular weights were synthesized, and their free volume characteristics were analyzed by positron annihilation lifetime spectroscopy and a molecular dynamics simulation. It indicated that the molar fraction of PDD in copolymers had a significant effect on free volume characteristics, while the molecular weight of copolymers exerted a slight influence on free volume when the molecular weight exceeded a critical region (intrinsic viscosity [η] > 68 ml g−1). PDD‐TFE copolymers with greater PDD molar fractions (i.e., 72% and 84%) showed bimodal distributions in positron lifetime and free volume size distributions, while PDD‐TFE copolymers with lower PDD molar fractions (i.e., 27% and 35%) exhibited a single peak. The long‐lifetime parameter τ3 was assigned to micro‐cavities formed by [‐(TFE)y‐PDD‐] segments and τ4 was attributed to micro‐cavities formed by [‐(PDD)x‐TFE‐] segments. The cis and trans transitions of PDD led to a local multilayer spiral structure with a 2.6–4.3 Å layer spacing, which would also increase the free volume of copolymers.

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“… Plots of ideal selectivity vs. permeability coefficient (Robeson diagrams with corresponding upper bounds) for gas pairs CO 2 -CH 4 ( a ), He-CH 4 ( b ), N 2 -CH 4 ( c ) and O 2 -N 2 ( d ) for original and treated with elemental fluorine films, and data for some perfluorinated polymers: perfluorinated polymers [ 17 , 31 , 102 , 103 , 104 , 105 ], virgin and fluorinated PTMSP [ 58 ], virgin and fluorinated low density polyethylene (LDPE), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) [ 44 ], virgin and fluorinated ethylcellulose (EC) and polyarylate [ 101 ], acetyl cellulose (AC) [ 65 ]. …”

Section: Figurementioning

confidence: 99%

Effect of Direct Fluorination on the Transport Properties and Swelling of Polymeric Materials: A Review

et al. 2021

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Fluorine-containing polymers occupy a peculiar niche among conventional polymers due to the unique combination of physicochemical properties. Direct surface fluorination of the polymeric materials is one of the approaches for the introduction of fluorine into the chemical structure that allows one to implement advantages of fluorinated polymers in a thin layer. Current review considers the influence of the surface interaction of the polymeric materials and membranes with elemental fluorine on gas, vapor and liquid transport as well as swelling and related phenomena. The increase in direct fluorination duration and concentration of fluorine in the fluorination mixture is shown to result mostly in a reduction of all penetrants permeability to a different extent, whereas selectivity of the selected gas pairs (He-H2, H2-CH4, He-CH4, CO2-CH4, O2-N2, etc.) increases. Separation parameters for the treated polymeric films approach Robeson’s upper bounds or overcome them. The most promising results were obtained for highly permeable polymer, polytrimethylsilylpropyne (PTMSP). The surface fluorination of rubbers in printing equipment leads to an improved chemical resistance of the materials towards organic solvents, moisturizing solutions and reduce diffusion of plasticizers, photosensitizers and other components of the polymeric blends. The direct fluorination technique can be also considered one of the approaches of fabrication of fuel cell membranes from non-fluorinated polymeric precursors that improves their methanol permeability, proton conductivity and oxidative stability.

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Gas permeation, diffusion, sorption and free volume of poly(2-trifluoromethyl-2-pentafluoroethyl-1,3-perfluorodioxole)

Cited by 30 publications

References 42 publications

Perfluoropolymer/Molecular Sieve Mixed-Matrix Membranes

Perfluoropolymer/Molecular Sieve Mixed-Matrix Membranes

Free volume characteristics of 2,2‐bistrifluoromethyl‐4,5‐difluoro‐1,3‐dioxole‐co‐tetrafluoroethylene copolymers: Effect of composition and molecular weight

Effect of Direct Fluorination on the Transport Properties and Swelling of Polymeric Materials: A Review

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