Polymers

Research

26 pages, 7121 KiB

Open AccessArticle

Morphological Study before and after Thermal Treatment of Polymer-Polymer Mixed-Matrix Membranes for Gas Separations

by Pedro Pradanos, Cenit Soto, Francisco Javier Carmona, Ángel E. Lozano, Antonio Hernández and Laura Palacio

Polymers 2024, 16(10), 1397; https://doi.org/10.3390/polym16101397 - 14 May 2024

Viewed by 965

Abstract

A good integration of the polymer materials that form a mixed-matrix membrane (MMM) for gas separation is essential to reaching interesting permselective properties. In this work, a porous polymer network (PPN), obtained by combining triptycene and trifluoroacetophenone, has been used as a filler, [...] Read more.

A good integration of the polymer materials that form a mixed-matrix membrane (MMM) for gas separation is essential to reaching interesting permselective properties. In this work, a porous polymer network (PPN), obtained by combining triptycene and trifluoroacetophenone, has been used as a filler, which was blended with two o-hydroxypolyamides (HPAs) that act as polymer matrices. These polymer matrices have been thermally treated to induce a thermal rearrangement (TR) of the HPAs to polybenzoxazoles (β-TR-PBOs) through a solid-state reaction. For its structural study, various techniques have been proposed that allow us to undertake a morphological investigation into the integration of these materials. To access the internal structure of the MMMs, three different methods were used: a polishing process for the material surface, the partial dissolution of the polymer matrix, or argon plasma etching. The argon plasma technique has not only revealed its potential to visualize the internal structure of these materials; it has also been proven to allow for the transformation of their permselective properties. Force modulation and phase contrast in lift-mode techniques, along with the topographic images obtained via the tapping mode using a scanning probe microscope (SPM), have allowed us to study the distribution of the filler particles and the interaction of the polymer and the filler. The morphological information obtained via SPM, along with that of other more commonly used techniques (SEM, TGA, DSC, FTIR, WASX, gas adsorption, and permeability measurements), has allowed us to postulate the most probable structural configuration in this type of system. Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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11 pages, 1779 KiB

Open AccessArticle

Preparation of Polyimide/Ionic Liquid Hybrid Membrane for CO₂/CH₄ Separation

by Xiaoyu Du, Shijun Zhao, Yanqing Qu, Hongge Jia, Shuangping Xu, Mingyu Zhang and Guoliang Geng

Polymers 2024, 16(3), 393; https://doi.org/10.3390/polym16030393 - 31 Jan 2024

Cited by 1 | Viewed by 1020

Abstract

Imidazole ionic liquids (IL_s) have good affinity and good solubility for carbon dioxide (CO₂). Such ionic liquids, combined with polyimide membrane materials, can solve the problem that, today, CO₂ is difficult to separate and recover. In this study, [...] Read more.

Imidazole ionic liquids (IL_s) have good affinity and good solubility for carbon dioxide (CO₂). Such ionic liquids, combined with polyimide membrane materials, can solve the problem that, today, CO₂ is difficult to separate and recover. In this study, the ionic liquid (IL) of 1-ethyl-3-methylimidazolium tetrafluoroborate (IL₁), 1-pentyl-3-methylimidazolium tetrafluoroborate (IL₂), 1-octyl-3-methylimidazolium tetrafluoroborate (IL₃), and 1-dodecylimidazolium tetrafluoroborate (IL₄) with different contents were added to a polyimide matrix, and a series of polyimide membranes blended with ionic liquid were prepared using a high-speed mixer. The mechanical properties and gas separation permeability of the membranes were investigated. Among them, the selectivity of the PI/IL₃ membrane for CO₂/CH₄ was 180.55, which was 2.5 times higher than the PI membrane, and its CO₂ permeability was 16.25 Barrer, which exceeded the Robeson curve in 2008; the separation performance of the membrane was the best in this work. Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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10 pages, 2847 KiB

Open AccessArticle

Nanofiltration Performance of Poly(p-xylylene) Nanofilms with Imidazole Side Chains

by Satsuki Yoshida, Takeshi Shii, Yu Kitazawa, Manuela L. Kim, Eugenio H. Otal, Yoshiyuki Hattori and Mutsumi Kimura

Polymers 2023, 15(15), 3309; https://doi.org/10.3390/polym15153309 - 4 Aug 2023

Cited by 1 | Viewed by 1337

Abstract

Herein, we report the nanofiltration performance of poly(p-xylylene) thin films with imidazole side chains that were deposited onto commercial polyethersulfone ultrafiltration membranes using a chemical vapor deposition process. The resulting thin films with a few tens of nanometers exhibited water permeation [...] Read more.

Herein, we report the nanofiltration performance of poly(p-xylylene) thin films with imidazole side chains that were deposited onto commercial polyethersulfone ultrafiltration membranes using a chemical vapor deposition process. The resulting thin films with a few tens of nanometers exhibited water permeation under a pressure difference of 0.5 MPa and selectively rejected water-soluble organic dyes based on their molecular sizes. Additionally, thin flaky ZIF-L crystals (Zn(mim)₂·(Hmim)_1/2·(H₂O)_3/2) (Hmim = 2-methylimidazole) formed on the surface of imidazole-containing poly(p-xylylene) films, and the composite films demonstrated the ability to adsorb methylene blue molecules within the cavities of ZIF-L. Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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20 pages, 8168 KiB

Open AccessArticle

Supported Imidazolium-Based Ionic Liquids on a Polysulfone Matrix for Enhanced CO₂ Capture

by David Domingo Huguet, Aitor Gual, Ricard Garcia-Valls and Adrianna Nogalska

Polymers 2022, 14(22), 4865; https://doi.org/10.3390/polym14224865 - 11 Nov 2022

Cited by 5 | Viewed by 1670

Abstract

The present work demonstrates the potential for improved CO₂ capture capabilities of ionic liquids (ILs) by supporting them on a polysulfone polymeric matrix. CO₂ is one of the main gases responsible for the greenhouse effect and is a focus of The [...] Read more.

The present work demonstrates the potential for improved CO₂ capture capabilities of ionic liquids (ILs) by supporting them on a polysulfone polymeric matrix. CO₂ is one of the main gases responsible for the greenhouse effect and is a focus of The European Commission, which committed to diminishing its emission to 55% by 2023. Various ILs based on combinations of 1-butyl-3-methyl- imidazolium cations and different anions (BMI·X) were synthesized and supported on a polysulfone porous membrane. The influence of the membrane structure and the nature of ILs on the CO₂ capture abilities were investigated. It was found that the membrane’s internal morphology and its surface characteristics influence its ILs sorption capacity and CO₂ solubility. In most of the studied configurations, supporting ILs on porous structures increased their contact surface and gas adsorption compared to the bulk ILs. The phenomenon was strongly pronounced in the case of ILs of high viscosity, where supporting them on porous structures resulted in a CO₂ solubility value increase of 10×. Finally, the highest CO₂ solubility value (0.24 mol_CO2/mol_IL) was obtained with membranes bearing supported ILs containing dicarboxylate anion (BMI.MAL). Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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15 pages, 4769 KiB

Open AccessArticle

Design of Robust FEP Porous Ultrafiltration Membranes by Electrospinning-Sintered Technology

by Kaikai Chen, Haoyang Ling, Hailiang Liu, Wei Zhao and Changfa Xiao

Polymers 2022, 14(18), 3802; https://doi.org/10.3390/polym14183802 - 11 Sep 2022

Cited by 1 | Viewed by 1828

Abstract

Perfluoropolymer membranes are widely used because of their good environmental adaptability. Herein, the ultrafine fibrous FEP porous membranes were fabricated with electrospinning-sintered technology. The effects of PVA content and sintering temperature on the fabricated membranes’ morphologies and properties were investigated. The results indicate [...] Read more.

Perfluoropolymer membranes are widely used because of their good environmental adaptability. Herein, the ultrafine fibrous FEP porous membranes were fabricated with electrospinning-sintered technology. The effects of PVA content and sintering temperature on the fabricated membranes’ morphologies and properties were investigated. The results indicate that a kind of dimensionally stable network structure was formed in the obtained ultrafine fibrous FEP porous membranes after sintering the nascent ultrafine fibrous FEP/PVA membranes. The optimal sintering conditions were obtained by comparing the membranes’ performance in terms of membrane morphology, hydrophobicity, mechanical strength, and porosity. When the sintering temperature was 300 °C for 10 min, the porosity, water contact angle, and liquid entry pressure of the membrane were 62.7%, 124.2° ± 2.1°, and 0.18 MPa, respectively. Moreover, the ultrafine fibrous FEP porous membrane at the optimal sintering conditions was tested in vacuum membrane distillation with a permeate flux of 15.1 L·m⁻²·h⁻¹ and a salt rejection of 97.99%. Consequently, the ultrafine fibrous FEP porous membrane might be applied in the seawater desalination field. Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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19 pages, 1832 KiB

Open AccessArticle

Adopting Sustainable Jatropha Oil Bio-Based Polymer Membranes as Alternatives for Environmental Remediation

by Nur Haninah Harun, Zurina Zainal Abidin, Umar Adam Majid, Mohamad Rezi Abdul Hamid, Abdul Halim Abdullah, Rizafizah Othaman and Mohd Yusof Harun

Polymers 2022, 14(16), 3325; https://doi.org/10.3390/polym14163325 - 16 Aug 2022

Cited by 3 | Viewed by 1995

Abstract

This study aimed to optimize the removal of Cu(II) ions from an aqueous solution using a Jatropha oil bio-based membrane blended with 0.50 wt% graphene oxide (JPU/GO 0.50 wt%) using a central composite model (CCD) design using response surface methodology. The input factors [...] Read more.

This study aimed to optimize the removal of Cu(II) ions from an aqueous solution using a Jatropha oil bio-based membrane blended with 0.50 wt% graphene oxide (JPU/GO 0.50 wt%) using a central composite model (CCD) design using response surface methodology. The input factors were the feed concentration (60–140) ppm, pressure (1.5–2.5) bar, and solution pH value (3–5). An optimum Cu(II) ions removal of 87% was predicted at 116 ppm feed concentration, 1.5 bar pressure, and pH 3.7, while the validated experimental result recorded 80% Cu(II) ions removal, with 95% of prediction intervals. A statistically non-significant term was removed from the analysis by the backward elimination method to improve the model’s accuracy. Using the reduction method, the predicted R² value was increased from −0.16 (−16%) to 0.88 (88%), suggesting that the reduced model had a good predictive ability. The quadratic regression model was significant (R² = 0.98) for the optimization prediction. Therefore, the results from the reduction model implied acceptable membrane performance, offering a better process optimization for Cu(II) ions removal. Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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16 pages, 3806 KiB

Open AccessArticle

High Efficiency Membranes Based on PTMSP and Hyper-Crosslinked Polystyrene for Toxic Volatile Compounds Removal from Wastewater

by Georgy Golubev, Stepan Sokolov, Tatyana Rokhmanka, Sergey Makaev, Ilya Borisov, Svetlana Khashirova and Alexey Volkov

Polymers 2022, 14(14), 2944; https://doi.org/10.3390/polym14142944 - 20 Jul 2022

Cited by 7 | Viewed by 2271

Abstract

For the first time, membranes based on poly(1-trimethylsilyl-1-propyne) (PTMSP) with 5–50 wt% loading of hyper-crosslinked polystyrene sorbent particles (HCPS) were obtained; the membranes were investigated for the problem of effective removal of volatile organic compounds from aqueous solutions using vacuum pervaporation. The industrial [...] Read more.

For the first time, membranes based on poly(1-trimethylsilyl-1-propyne) (PTMSP) with 5–50 wt% loading of hyper-crosslinked polystyrene sorbent particles (HCPS) were obtained; the membranes were investigated for the problem of effective removal of volatile organic compounds from aqueous solutions using vacuum pervaporation. The industrial HCPS sorbent Purolite Macronet™ MN200 was chosen due to its high sorption capacity for organic solvents. It has been found that the membranes are asymmetric when HCPS content is higher than 30 wt%; scanning electron microscopy of the cross-sections the membranes demonstrate that they have a clearly defined thin layer, consisting mainly of PTMSP, and a thick porous layer, consisting mainly of HCPS. The transport and separation characteristics of PTMSP membranes with different HCPS loading were studied during the pervaporation separation of binary and multicomponent mixtures of water with benzene, toluene and xylene. It was shown that the addition of HCPS up to 30 wt% not only increases the permeate fluxes by 4–7 times, but at the same time leads to 1.5–2 fold increase in the separation factor. It was possible to obtain separation factors exceeding 1000 for all studied mixtures at high permeate fluxes (0.5–1 kg/m²∙h) in pervaporation separation of binary solutions. Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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Review

Jump to: Research, Other

27 pages, 9931 KiB

Open AccessReview

Emerging Trends in Porogens toward Material Fabrication: Recent Progresses and Challenges

by D. Shanthana Lakshmi, Radha K. S., Roberto Castro-Muñoz and Marek Tańczyk

Polymers 2022, 14(23), 5209; https://doi.org/10.3390/polym14235209 - 30 Nov 2022

Cited by 11 | Viewed by 2795

Abstract

Fabrication of tailor-made materials requires meticulous planning, use of technical equipments, major components and suitable additives that influence the end application. Most of the processes of separation/transport/adsorption have environmental applications that demands a material to be with measurable porous nature, stability (mechanical, thermal) [...] Read more.

Fabrication of tailor-made materials requires meticulous planning, use of technical equipments, major components and suitable additives that influence the end application. Most of the processes of separation/transport/adsorption have environmental applications that demands a material to be with measurable porous nature, stability (mechanical, thermal) and morphology. Researchers say that a vital role is played by porogens in this regard. Porogens (i.e., synthetic, natural, mixed) and their qualitative and quantitative influence on the substrate material (polymers (bio, synthetic), ceramic, metals, etc.) and their fabrication processes are summarized. In most cases, porogens critically influence the morphology, performance, surface and cross-section, which are directly linked to material efficiency, stability, reusability potential and its applications. However, currently there are no review articles exclusively focused on the porogen pores’ role in material fabrication in general. Accordingly, this article comprises a review of the literature on various types of porogens, their efficiency in different host materials (organic, inorganic, etc.), pore size distribution (macro, micro and nano), their advantages and limitations, to a certain extent, and their critical applications. These include separation, transport of pollutants, stability improvement and much more. The progress made and the remaining challenges in porogens’ role in the material fabrication process need to be summarized for researcher’s attention. Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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Other

Jump to: Research, Review

16 pages, 4240 KiB

Open AccessEssay

Axial Crystal Growth Evolution and Crystallization Characteristics of Bi-Continuous Polyamide 66 Membranes Prepared via the Cold Non-Solvent-Induced Phase Separation Technique

by Jiangyi Yan, Lihong Nie, Guiliang Li, Yuanlu Zhu, Ming Gao, Ruili Wu and Beifu Wang

Polymers 2022, 14(9), 1706; https://doi.org/10.3390/polym14091706 - 22 Apr 2022

Cited by 5 | Viewed by 1956

Abstract

Polyamide 66 microporous membranes were prepared by cold non-solvent-induced phase separation using polyamide 66-formic acid-propylene carbonate as a ternary membrane-forming system. The formed membranes exhibited a special bicontinuous structure consisting of interglued spherical crystals or interlocked bundles of microcrystalline aggregates. The variation of [...] Read more.

Polyamide 66 microporous membranes were prepared by cold non-solvent-induced phase separation using polyamide 66-formic acid-propylene carbonate as a ternary membrane-forming system. The formed membranes exhibited a special bicontinuous structure consisting of interglued spherical crystals or interlocked bundles of microcrystalline aggregates. The variation of the microporous structure under the influence of preparation conditions, solvent, aging time, and polymer concentration affects the comprehensive performance of the membranes. For example, the cold-induced operation and the use of different membrane-forming solvents contributed to the crystallization of polyamide 66, resulting in an increased contact angle of polyamide 66 membranes, obtaining a high resistance to contamination of up to 73.5%. Moreover, the formed membranes still have high mechanical strength. Full article

(This article belongs to the Special Issue Advanced Polymer Membranes for Adsorption and Separation Applications)

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