Physical aging of polymers of intrinsic microporosity: a SAXS/WAXS study

2014 ◽  
Vol 2 (30) ◽  
pp. 11742-11752 ◽  
Author(s):  
Amanda G. McDermott ◽  
Peter M. Budd ◽  
Neil B. McKeown ◽  
Coray M. Colina ◽  
James Runt
Keyword(s):  
Film Thickness ◽  
Free Volume ◽  
Physical Aging ◽  
Gas Separations ◽  
X Ray ◽  
Membrane Performance ◽  
X Ray Scattering ◽  
Polymeric Glasses ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

X-ray scattering patterns from these high free-volume polymeric glasses contain a feature strongly associated with porosity; it is sensitive to time, temperature and film thickness in a manner consistent with physical aging, which impacts membrane performance in gas separations.

scholarly journals Polymer of Intrinsic Microporosity (PIM-1) Membranes Treated with Supercritical CO2

Membranes ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 41 ◽  
Author(s):  
Colin Scholes ◽  
Shinji Kanehashi
Keyword(s):  
Free Volume ◽  
Gas Separation ◽  
Supercritical Co2 ◽  
Physical Aging ◽  
Size Exclusion ◽  
Membrane Morphology ◽  
Polymers Of Intrinsic Microporosity ◽  
Micro Cavity ◽  
The Impact ◽  
Intrinsic Microporosity

Polymers of intrinsic microporosity (PIMs) are a promising membrane material for gas separation, because of their high free volume and micro-cavity size distribution. This is countered by PIMs-based membranes being highly susceptible to physical aging, which dramatically reduces their permselectivity over extended periods of time. Supercritical carbon dioxide is known to plasticize and partially solubilise polymers, altering the underlying membrane morphology, and hence impacting the gas separation properties. This investigation reports on the change in PIM-1 membranes after being exposed to supercritical CO2 for two- and eight-hour intervals, followed by two depressurization protocols, a rapid depressurization and a slow depressurization. The exposure times enables the impact contact time with supercritical CO2 has on the membrane morphology to be investigated, as well as the subsequent depressurization event. The density of the post supercritical CO2 exposed membranes, irrespective of exposure time and depressurization, were greater than the untreated membrane. This indicated that supercritical CO2 had solubilised the polymer chain, enabling PIM-1 to rearrange and contract the free volume micro-cavities present. As a consequence, the permeabilities of He, CH4, O2 and CO2 were all reduced for the supercritical CO2-treated membranes compared to the original membrane, while N2 permeability remained unchanged. Importantly, the physical aging properties of the supercritical CO2-treated membranes altered, with only minor reductions in N2, CH4 and O2 permeabilities observed over extended periods of time. In contrast, He and CO2 permeabilities experienced similar physical aging in the supercritical treated membranes to that of the original membrane. This was interpreted as the supercritical CO2 treatment enabling micro-cavity contraction to favour the smaller CO2 molecule, due to size exclusion of the larger N2, CH4 and O2 molecules. Therefore, physical aging of the treated membranes only had minor impact on N2, CH4 and O2 permeability; while the smaller He and CO2 gases experience greater permeability loss. This result implies that supercritical CO2 exposure has potential to limit physical aging performance loss in PIM-1 based membranes for O2/N2 separation.

scholarly journals Free Volume and Gas Permeation in Anthracene Maleimide-Based Polymers of Intrinsic Microporosity

Membranes ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 214-227 ◽  
Author(s):  
Muntazim Khan ◽  
Volkan Filiz ◽  
Thomas Emmler ◽  
Volker Abetz ◽  
Toenjes Koschine ◽  
...  
Keyword(s):  
Free Volume ◽  
Gas Permeation ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

Strain Analysis in Thin La1−xCaxMnO3 Films by Grazing Incidence X-ray Scattering

1999 ◽  
Vol 602 ◽  
Author(s):  
M. Petit ◽  
L. J. Martinez-Miranda ◽  
M. Rajeswari ◽  
A. Biswas ◽  
D. J. Kang ◽  
...  
Keyword(s):  
Film Thickness ◽  
Lattice Mismatch ◽  
Compressive Strain ◽  
Strain Analysis ◽  
Grazing Incidence ◽  
Relaxation Processes ◽  
Near Surface ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

AbstractWe have performed depth profile analyses of the lattice parameters in epitaxial thin films of La1−xCaxMno3 (LCMO), where x = 0.33 or 0.3, to understand the evolution of strain relaxation processes in these materials. The analyses were done using Grazing Incidence X-ray Scattering (GIXS) on films of different thicnesses on two different substrates, (100) oriented LaAlO3 (LAO), with a lattice mismatch of ∼2% and (110) oriented NGO, with a lattice mismatch of less than 0.1%. Films grown on LAO can exhibit up to three in-plane strained lattice constants, corresponding to a slight orthorhombic distortion of the crystal, as well as near-surface and columnar lattice relaxation. As a function of film thickness, a crossover from a strained film to a mixture of strained and relaxed regions in the film occurs in the range of 700 Å. The structural evolution at this thickness coincides with a change in the resistivity curve near the metalinsulator transition. The in-plane compressive strain has a range of 0.2 – 1.5%, depending on the film thickness for filsm in the range of 400 - 1500 A.

Characterizing the Structure of Organic Molecules of Intrinsic Microporosity by Molecular Simulations and X-ray Scattering

2012 ◽  
Vol 117 (1) ◽  
pp. 355-364 ◽  
Author(s):  
Lauren J. Abbott ◽  
Amanda G. McDermott ◽  
Annalaura Del Regno ◽  
Rupert G. D. Taylor ◽  
C. Grazia Bezzu ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Molecular Simulations ◽  
X Ray ◽  
X Ray Scattering ◽  
Intrinsic Microporosity ◽  
Ray Scattering

Free volume and lamellar structure of poly vinyl alcohol-nanosized BaTiO3 composite: Positron annihilation and small angle X-ray scattering study

2016 ◽  
Vol 84 ◽  
pp. 100-110 ◽  
Author(s):  
Sandeep K. Sharma ◽  
Jyoti Prakash ◽  
Jitendra Bahadur ◽  
Manjulata Sahu ◽  
Subhashish Mazumder ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Small Angle ◽  
Vinyl Alcohol ◽  
Lamellar Structure ◽  
Poly Vinyl Alcohol ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Ray Scattering

X‐Ray Scattering from a ``Free‐Volume'' Liquid

1953 ◽  
Vol 21 (10) ◽  
pp. 1772-1773
Author(s):  
Louis H. Lund
Keyword(s):  
Free Volume ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Changes In The Characteristics Of The Free Volume Of Glassy Polymers During Deformation And Relaxation.

1991 ◽  
Vol 227 ◽  
Author(s):  
M.I. Tsapovestsky ◽  
V.K. Lavrentiev ◽  
S.A. Tishin
Keyword(s):  
Dielectric Loss ◽  
Positron Annihilation ◽  
Free Volume ◽  
Small Angle ◽  
Mechanical Tests ◽  
Glassy Polymers ◽  
Volume Relaxation ◽  
X Ray ◽  
X Ray Scattering ◽  
Original Interpretation

ABSTRACTThe behavior of glassy polymers was studied with the aid of mechanical tests on the basis of free volume. Three types of experiments were carried out and interpreted using modern ideas about the structure of free volume. They were: 1. The study of changes in the total free volume occurring as a result of deformation (by measurement of density) 2. The study of micro voids and their changes on deformation using small angle X-ray scattering (SAXS) and positron annihilation 3. The study of mobile regions by the measurement of dielectric loss (using an original interpretation) during deformation. This allows several parts of the total free volume to be distinguished and investigated. A model for the free volume relaxation during deformation is proposed.

scholarly journals Pentiptycene-based ladder polymers with configurational free volume for enhanced gas separation performance and physical aging resistance

2021 ◽  
Vol 118 (37) ◽  
pp. e2022204118
Author(s):  
Tanner J. Corrado ◽  
Zihan Huang ◽  
Dezhao Huang ◽  
Noah Wamble ◽  
Tengfei Luo ◽  
...  
Keyword(s):  
Free Volume ◽  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeation ◽  
Separation Performance ◽  
Structure Property ◽  
Mixed Gas ◽  
Initial Separation ◽  
Primary Advantage ◽  
Polymers Of Intrinsic Microporosity

Polymers of intrinsic microporosity (PIMs) have shown promise in pushing the limits of gas separation membranes, recently redefining upper bounds for a variety of gas pair separations. However, many of these membranes still suffer from reductions in permeability over time, removing the primary advantage of this class of polymer. In this work, a series of pentiptycene-based PIMs incorporated into copolymers with PIM-1 are examined to identify fundamental structure–property relationships between the configuration of the pentiptycene backbone and its accompanying linear or branched substituent group. The incorporation of pentiptycene provides a route to instill a more permanent, configuration-based free volume, resistant to physical aging via traditional collapse of conformation-based free volume. PPIM-ip-C and PPIM-np-S, copolymers with C- and S-shape backbones and branched isopropoxy and linear n-propoxy substituent groups, respectively, each exhibited initial separation performance enhancements relative to PIM-1. Additionally, aging-enhanced gas permeabilities were observed, a stark departure from the typical permeability losses pure PIM-1 experiences with aging. Mixed-gas separation data showed enhanced CO2/CH4 selectivity relative to the pure-gas permeation results, with only ∼20% decreases in selectivity when moving from a CO2 partial pressure of ∼2.4 to ∼7.1 atm (atmospheric pressure) when utilizing a mixed-gas CO2/CH4 feed stream. These results highlight the potential of pentiptycene’s intrinsic, configurational free volume for simultaneously delivering size-sieving above the 2008 upper bound, along with exceptional resistance to physical aging that often plagues high free volume PIMs.

scholarly journals Nanofiller-tuned microporous polymer molecular sieves for energy and environmental processes

2016 ◽  
Vol 4 (1) ◽  
pp. 270-279 ◽  
Author(s):  
Qilei Song ◽  
Shuai Cao ◽  
Robyn H. Pritchard ◽  
Hazim Qiblawey ◽  
Eugene M. Terentjev ◽  
...  
Keyword(s):  
Molecular Sieves ◽  
Gas Separations ◽  
Crosslinked Polymers ◽  
Environmental Processes ◽  
Microporous Polymer ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

Incorporating nanofillers into thermal-oxidatively crosslinked polymers of intrinsic microporosity (PIM-1) generates highly permeable and selective molecular sieves for gas separations.

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