Special Issue "Gas Transport in Glassy Polymers"

A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Membrane Transport Phenomena".

Deadline for manuscript submissions: closed (15 April 2019)

Special Issue Editors

Guest Editor
Prof. Dr. Giulio Cesare Sarti

Dipartimento di Ingegneria Civile Chimica Ambientale e dei Materiali, Alma Mater Studiorum Universita di Bologna, Via Terracini, 28-I-40131 Bologna, Italy
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Interests: gas separations; glassy polymers; bioseparations; affinity membranes; solubility; permeability; diffusivity
Guest Editor
Prof. Dr. Maria Grazia De Angelis

Dipartimento di Ingegneria Civile Chimica Ambientale e dei Materiali, Alma Mater Studiorum Universita di Bologna, Via Terracini, 28-I-40131 Bologna, Italy
Website | E-Mail
Interests: mass transport; thermodynamic models; diffusion; molecular simulation; equations of state; glassy polymers; mixed matrix membranes; gas separation

Special Issue Information

Dear Colleagues,

We warmly invite you to submit your original work or review article to this Special Issue of “Gas Transport in Glassy Polymers”. Glassy polymers are election materials for many industrial separations of gaseous and liquid mixtures; for environmentally relevant processes, such as CO2 capture, natural gas sweetening and water purification, as well as for the production of energy, such as in fuel cells, batteries, and electromembrane devices. A fundamental analysis of such materials is required to address the most peculiar features of such materials and, in particular, their non-equilibrium nature.

This issue is devoted to fundamental analysis of fluid sorption, diffusion, and permeation in glassy polymers suitable for the above mentioned applications (e.g. fluid separation, carbon capture, water purification, energy production and storage, biological applications, sensors, etc.). Topics of interest include the experimental analysis of fundamental aspects of sorption and transport in glassy materials, such as glass transition, ageing, thin films, nanoconfinement, plasticization, swelling, competitive sorption, and stress effects. We will also welcome modeling works presenting macroscopic, atomistic, mesoscopic, or multiscale approaches that describe sorption and transport in glassy matrices.

We are looking forward to receiving your work for this Special Issue.

Prof. Dr. Giulio C. Sarti
Prof. Dr. Maria Grazia De Angelis
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Membranes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • membranes
  • glassy polymers
  • gas transport
  • separation
  • sorption
  • models
  • non equilibrium
  • permeation
  • diffusion
  • glass transition
  • ageing
  • plasticization

Published Papers (8 papers)

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Research

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Open AccessArticle Sorption Thermodynamics of CO2, H2O, and CH3OH in a Glassy Polyetherimide: A Molecular Perspective
Received: 15 November 2018 / Revised: 18 January 2019 / Accepted: 18 January 2019 / Published: 1 February 2019
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Abstract
In this paper, the sorption thermodynamics of low-molecular-weight penetrants in a glassy polyetherimide, endowed with specific interactions, is addressed by combining an experimental approach based on vibrational spectroscopy with thermodynamics modeling. This modeling approach is based on the extension of equilibrium theories to [...] Read more.
In this paper, the sorption thermodynamics of low-molecular-weight penetrants in a glassy polyetherimide, endowed with specific interactions, is addressed by combining an experimental approach based on vibrational spectroscopy with thermodynamics modeling. This modeling approach is based on the extension of equilibrium theories to the out-of-equilibrium glassy state. Specific interactions are accounted for in the framework of a compressible lattice fluid theory. In particular, the sorption of carbon dioxide, water, and methanol is illustrated, exploiting the wealth of information gathered at a molecular level from Fourier-transform infrared (FTIR) spectroscopy to tailor thermodynamics modeling. The investigated penetrants display a different interacting characteristic with respect to the polymer substrate, which reflects itself in the sorption thermodynamics. For the specific case of water, the outcomes from molecular dynamics simulations are compared with the results of the present analysis. Full article
(This article belongs to the Special Issue Gas Transport in Glassy Polymers)
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Open AccessArticle Experimental Mixed-Gas Permeability, Sorption and Diffusion of CO2-CH4 Mixtures in 6FDA-mPDA Polyimide Membrane: Unveiling the Effect of Competitive Sorption on Permeability Selectivity
Received: 8 November 2018 / Revised: 10 December 2018 / Accepted: 20 December 2018 / Published: 8 January 2019
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Abstract
The nonideal behavior of polymeric membranes during separation of gas mixtures can be quantified via the solution-diffusion theory from experimental mixed-gas solubility and permeability coefficients. In this study, CO2-CH4 mixtures were sorbed at 35 °C in 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA)-m-phenylenediamine (mPDA)—a [...] Read more.
The nonideal behavior of polymeric membranes during separation of gas mixtures can be quantified via the solution-diffusion theory from experimental mixed-gas solubility and permeability coefficients. In this study, CO2-CH4 mixtures were sorbed at 35 °C in 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA)-m-phenylenediamine (mPDA)—a polyimide of remarkable performance. The existence of a linear trend for all data of mixed-gas CO2 versus CH4 solubility coefficients—regardless of mixture concentration—was observed for 6FDA-mPDA and other polymeric films; the slope of this trend was identified as the ratio of gas solubilities at infinite dilution. The CO2/CH4 mixed-gas solubility selectivity of 6FDA-mPDA and previously reported polymers was higher than the equimolar pure-gas value and increased with pressure from the infinite dilution value. The analysis of CO2-CH4 mixed-gas concentration-averaged effective diffusion coefficients of equimolar feeds showed that CO2 diffusivity was not affected by CH4. Our data indicate that the decrease of CO2/CH4 mixed-gas diffusion, and permeability selectivity from the pure-gas values, resulted from an increase in the methane diffusion coefficient in mixtures. This effect was the result of an alteration of the size sieving properties of 6FDA-mPDA as a consequence of CO2 presence in the 6FDA-mPDA film matrix. Full article
(This article belongs to the Special Issue Gas Transport in Glassy Polymers)
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Open AccessArticle Modelling Mixed-Gas Sorption in Glassy Polymers for CO2 Removal: A Sensitivity Analysis of the Dual Mode Sorption Model
Received: 31 October 2018 / Revised: 29 November 2018 / Accepted: 20 December 2018 / Published: 4 January 2019
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Abstract
In an effort to reduce the experimental tests required to characterize the mixed-gas solubility and solubility-selectivity of materials for membrane separation processes, there is a need for reliable models which involve a minimum number of adjustable parameters. In this work, the ability of [...] Read more.
In an effort to reduce the experimental tests required to characterize the mixed-gas solubility and solubility-selectivity of materials for membrane separation processes, there is a need for reliable models which involve a minimum number of adjustable parameters. In this work, the ability of the Dual Mode Sorption (DMS) model to represent the sorption of CO2/CH4 mixtures in three high free volume glassy polymers, poly(trimethylsilyl propyne) (PTMSP), the first reported polymer of intrinsic microporosity (PIM-1) and tetrazole-modified PIM-1 (TZ-PIM), was tested. The sorption of gas mixtures in these materials suitable for CO2 separation has been characterized experimentally in previous works, which showed that these systems exhibit rather marked deviations from the ideal pure-gas behavior, especially due to competitive effects. The accuracy of the DMS model in representing the non-idealities that arise during mixed-gas sorption was assessed in a wide range of temperatures, pressures and compositions, by comparing with the experimental results available. Using the parameters obtained from the best fit of pure-gas sorption isotherms, the agreement between the mixed-gas calculations and the experimental data varied greatly in the different cases inspected, especially in the case of CH4 absorbed in mixed-gas conditions. A sensitivity analysis revealed that pure-gas data can be represented with the same accuracy by several different parameter sets, which, however, yield markedly different mixed-gas predictions, that, in some cases, agree with the experimental data only qualitatively. However, the multicomponent calculations with the DMS model yield more reliable results than the use of pure-gas data in the estimation of the solubility-selectivity of the material. Full article
(This article belongs to the Special Issue Gas Transport in Glassy Polymers)
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Open AccessArticle Temperature and Pressure Dependence of Gas Permeation in a Microporous Tröger’s Base Polymer
Membranes 2018, 8(4), 132; https://doi.org/10.3390/membranes8040132
Received: 31 October 2018 / Revised: 30 November 2018 / Accepted: 5 December 2018 / Published: 14 December 2018
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Abstract
Gas transport properties of PIM-EA(H2)-TB, a microporous Tröger’s base polymer, were systematically studied over a range of pressure and temperature. Permeability coefficients of pure CO2, N2, CH4 and H2 were determined for upstream pressures up [...] Read more.
Gas transport properties of PIM-EA(H2)-TB, a microporous Tröger’s base polymer, were systematically studied over a range of pressure and temperature. Permeability coefficients of pure CO2, N2, CH4 and H2 were determined for upstream pressures up to 20 bar and temperatures up to 200 °C. PIM-EA(H2)-TB exhibited high permeability coefficients in absence of plasticization phenomena. The permeability coefficient of N2, CH4 and H2 increased with increasing temperature while CO2 permeability decreased with increasing temperature as expected for a glassy polymer. The diffusion and solubility coefficients were also analysed individually and compared with other polymers of intrinsic microporosity. From these results, the activation energies of permeation, diffusion and sorption enthalpies were calculated using an Arrhenius equation. Full article
(This article belongs to the Special Issue Gas Transport in Glassy Polymers)
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Open AccessArticle Study of the Effect of Inorganic Particles on the Gas Transport Properties of Glassy Polyimides for Selective CO2 and H2O Separation
Membranes 2018, 8(4), 128; https://doi.org/10.3390/membranes8040128
Received: 6 November 2018 / Revised: 30 November 2018 / Accepted: 5 December 2018 / Published: 9 December 2018
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Abstract
Three polyimides and six inorganic fillers in a form of nanometer-sized particles were studied as thick film solution cast mixed matrix membranes (MMMs) for the transport of CO2, CH4, and H2O. Gas transport properties and electron microscopy [...] Read more.
Three polyimides and six inorganic fillers in a form of nanometer-sized particles were studied as thick film solution cast mixed matrix membranes (MMMs) for the transport of CO2, CH4, and H2O. Gas transport properties and electron microscopy images indicate good polymer-filler compatibility for all membranes. The only filler type thatdemonstrated good distribution throughout the membrane thickness at 10 wt.% loading was BaCe0.2Zr0.7Y0.1O3 (BCZY). The influence of this filler on MMM gas transport properties was studied in detail for 6FDA-6FpDA in a filler content range from one to 20 wt.% and for Matrimid® and P84® at 10 wt.% loading. The most promising result was obtained for Matrimid®—10 wt.% BCZY MMM, which showed improvement in CO2 and H2O permeabilities accompanied by increased CO2/CH4 selectivity and high water selective membrane at elevated temperatures without H2O/permanent gas selectivity loss. Full article
(This article belongs to the Special Issue Gas Transport in Glassy Polymers)
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Open AccessArticle Poly(1-trimethylsilyl-1-propyne)-Based Hybrid Membranes: Effects of Various Nanofillers and Feed Gas Humidity on CO2 Permeation
Received: 13 August 2018 / Revised: 24 August 2018 / Accepted: 24 August 2018 / Published: 5 September 2018
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Abstract
Poly(1-trimethylsilyl-1-propyne) (PTMSP) is a high free volume polymer with exceptionally high gas permeation rate but the serious aging problem and low selectivity have limited its application as CO2 separation membrane material. Incorporating inorganic nanoparticles in polymeric membranes has been a common approach [...] Read more.
Poly(1-trimethylsilyl-1-propyne) (PTMSP) is a high free volume polymer with exceptionally high gas permeation rate but the serious aging problem and low selectivity have limited its application as CO2 separation membrane material. Incorporating inorganic nanoparticles in polymeric membranes has been a common approach to improve the separation performance of membranes, which has also been used in PTMSP based membrane but mostly with respect to tackling the aging issues. Aiming at increasing the CO2 selectivity, in this work, hybrid membranes containing four types of selected nanofillers (from 0 to 3D) were fabricated using PTMSP as the polymer matrix. The effects of the various types of nanofillers on the CO2 separation performance of the resultant membranes were systematically investigated in humid conditions. The thermal, chemical and morphologic properties of the hybrid membranes were characterized using TGA, FTIR and SEM. The gas permeation properties of the hybrid membranes were evaluated using mixed gas permeation test with the presence of water vapour to simulate the flue gas conditions. Experiments show that the addition of different fillers results in significantly different separation performances; The addition of ZIF-L porous 2D filler improves the CO2/N2 selectivity at the expenses of CO2 permeability, while the addition of TiO2, ZIF-7 and ZIF-8 increases the CO2 permeability but the CO2/N2 selectivity decreases. Full article
(This article belongs to the Special Issue Gas Transport in Glassy Polymers)
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Review

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Open AccessReview Models for Facilitated Transport Membranes: A Review
Received: 9 December 2018 / Revised: 14 January 2019 / Accepted: 15 January 2019 / Published: 2 February 2019
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Abstract
Facilitated transport membranes are particularly promising in different separations, as they are potentially able to overcome the trade-off behavior usually encountered in solution-diffusion membranes. The reaction activated transport is a process in which several mechanisms take place simultaneously, and requires a rigorous theoretical [...] Read more.
Facilitated transport membranes are particularly promising in different separations, as they are potentially able to overcome the trade-off behavior usually encountered in solution-diffusion membranes. The reaction activated transport is a process in which several mechanisms take place simultaneously, and requires a rigorous theoretical analysis, which unfortunately is often neglected in current studies more focused on material development. In this work, we selected and reviewed the main mathematical models introduced to describe mobile and fixed facilitated transport systems in steady state conditions, in order to provide the reader with an overview of the existing mathematical tools. An analytical solution to the mass transport problem cannot be achieved, even when considering simple reaction schemes such as that between oxygen (solute) and hemoglobin (carrier) ( A + C A C ), that was thoroughly studied by the first works dealing with this type of biological facilitated transport. Therefore, modeling studies provided approximate analytical solutions and comparison against experimental observations and exact numerical calculations. The derivation, the main assumptions, and approximations of such modeling approaches is briefly presented to assess their applicability, precision, and flexibility in describing and understanding mobile and fixed site carriers facilitated transport membranes. The goal is to establish which mathematical tools are more suitable to support and guide the development and design of new facilitated transport systems and materials. Among the models presented, in particular, those from Teramoto and from Morales-Cabrera et al. seem the more flexible and general ones for the mobile carrier case, while the formalization made by Noble and coauthors appears the most complete in the case of fixed site carrier membranes. Full article
(This article belongs to the Special Issue Gas Transport in Glassy Polymers)
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Open AccessReview Perfluoropolymer/Molecular Sieve Mixed-Matrix Membranes
Received: 30 December 2018 / Revised: 19 January 2019 / Accepted: 21 January 2019 / Published: 23 January 2019
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Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Gas Transport in Glassy Polymers)
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