CHEMISTRY OF MATERIALS
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2020
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IF 9.567
Xiaobai Li,Hongwei Ma,Peng Wang,Zhenchao Liu,Jinwu Peng,Wei Hu,Zhenhua Jiang,Baijun Liu,Michael D. Guiver
Phosphoric acid-doped polybenzimidazole (PA-PBI) used in high-temperature proton exchange membranes (HT-PEMs) frequently suffers from a serious loss of mechanical strength because of the “plasticizing effect” of the dopant acid. Conventional cross-linking approaches generally enhance membrane stability. However, acid doping levels (ADLs) and consequently proton conductivity inevitably decrease. This is due to the formation of more compact molecular structures and a reduced amount of functional imidazole units, caused by their consumption in introducing the cross-linker. To resolve the common problems of current PA-PBI-based HT-PEMs, herein, a highly acidophilic imidazole-rich cross-linked network with superior “antiplasticizing” ability is constructed based on a novel multifunctional cross-linker. This unique bischloro/bibenzimidazole (“A2B2-type”) molecular structure has extremely high reactivity, including “self-reaction” among the cross-linkers and “inter-reaction” between the cross-linker and PBI molecules. The resulting imidazole-rich cross-linked membranes exhibit the desired combination of high ADLs, high conductivity, outstanding dimensional–mechanical stability, and excellent fuel cell performance. In comparison to a corresponding linear PBI membrane, one membrane with a high content of the cross-linker of 30% has a 100 wt % increased acid uptake, a doubling in proton conductivity at 200 °C, and a maximum power density of 533 mW·cm–2 at 160 °C without humidification.
研究领域:
材料科学
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能源工程
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DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2018
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IF 6.578
Shasha Zhao,Jiayou Liao,Danfeng Li,Xiaodong Wang,Nanwen Li
The novel gas separation membranes have been prepared by blending highly gas permeable polymer of intrinsic microporosity (PIM-1) and with Tröger's Base polymer (TB). Interestingly, it was found firstly that the PIM-1 polymer was miscible with Tröger's Base polymer in any proportion. It was assumed that the excellent compatibility between two polymers could be attributed to the interaction between CN group in PIM-1 and N atoms in Tröger's Base moieties, as confirmed by ATR-IR results. Thus, flexible, tough and transparent blending membranes (PIM/TB) at different compositions between PIM-1 and TB were obtained by solution casting. The SEM results further confirmed the homogeneous morphology of blending membranes, indicating the excellent compatibility between two polymers. The gas separation performance testing by the volume-constant method suggested that the PIM/TB blending membrane showed lower pure gas permeability but higher ideal permselectivity than that of the pristine PIM-1 membrane, probably due to the lower d-spacing of TB polymers from commercial aromatic diamine which has a rotatable bond as confirmed by XRD results. The highest ideal permselectivity of CO 2 /CH 4 was obtained for PIM/TB (6:4) membranes with CO 2 permeability of 2585Barrer. Moreover, the excellent anti-plasticization ability of CO 2 was observed for the blending membranes. The temperature dependence of gas separation and ideal permselectivity had also been observed for the membranes. The results suggested that the ideal permselectivity, particularly for the CO 2 /N 2 and CO 2 /CH 4 at lower temperature were much higher than that of the membrane at high temperature in spite of the decreasing permeability of CO 2 . The highest ideal permselectivity was achieved as high as 54.3 for CO 2 /N 2 at − 25 ℃ for PIM/TB(8:2) membrane. Thus, the strategy of blending Tröger's Base with PIM-1 showed a promising approach for high performance gas separation membrane.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
ACS Applied Polymer Materials
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2020
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IF 0
Xiuling Chen,Zhiguang Zhang,Lei Wu,Xingchen Liu,Shan Xu,Johnson E. Efome,Xinghua Zhang,Nanwen Li
Certain polymers with very high free volume demonstrate a continuous network of interconnected void spaces due to the shape and rigidity of its macromolecular composition; as such, it becomes an intrinsic property for these polymers otherwise seen as polymers of intrinsic microporosity (PIM). Methylated polymers of intrinsic microporosity (PIM-M), bromoalkylated PIM (PIM-BM-x), and thermally self-cross-linked PIM-BM-x were designed and prepared for gas separation performance enhancements. The PIM-BM-x polymeric membranes demonstrated exceptional gas separation performance compared with PIM-M and surpassed the 2008 Robeson upper bound line, that is, the selectivities of PIM-BM-100 membrane for CO2/CH4 and O2/N2 were as high as 25.8 and 5.6, respectively. The gas permeability testing indicated that the permeability of CO2 and O2 for the cross-linked PIM-BM-70 was 48.3 and 11.1 barrer, respectively, while the selectivities of CO2/CH4 and O2/N2 were, respectively, 43.9 and 6.5 after self-cross-linking at 300 °C for 5 h. More importantly, the cross-linked membrane showed excellent antiplasticization ability with a plasticization pressure higher than 500 psi. This value is relatively greater than the pristine uncross-linked PIM-BM membrane (100 psi).
研究领域:
材料科学
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化学工程
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DOI
JOURNAL OF MEMBRANE SCIENCE
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2022
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IF 10.53
Can Wang,Zhili Cai,Wei Xie,Yang Jiao,Lu Liu,Lili Gong,Qi-Wei Zhang,Xiaohua Ma,Hongjun Zhang,Shuangjiang Luo
Thermally induced chemical crosslinking has attracted substantial attention for fabricating plasticization resistant membranes due to the facile structure tunability that enables the construction of robust and well-defined architecture for gas separation. In this study, we report a new series of dual thermally crosslinkable polyimides derived from 4,4′-diamino-2,2′-biphenyldicarboxylic acid (DCB) containing two carboxyl groups, and a systematic investigation of the thermal treatment above and below T g demonstrated the decarboxylation-induced crosslinking. The dual thermally crosslinked membranes were insoluble in common organic solvents and maintained excellent mechanical properties . Due to the evolution of CO 2 and collapse of chain segments during thermal treatment, the crosslinked membranes exhibited hierarchical microcavity size distribution featuring ultra-micropore size in the range of 2.0–6.0 Å and micropore size in the range of 6.5–10.0 Å. Gas transport properties of the crosslinked membranes were feasibly tuned through the chemical compositions and thermal treatment procedures. For instance, the CO 2 permeability of crosslinked 6FDA-DAM 0.7 -TFMB 0.1 -DCB 0.2 increased almost three-fold with only a slight decrease in CO 2 /CH 4 selectivity. The crosslinked membranes also demonstrated superior plasticization resistance with mixed-gas feed pressure up to 40 bar and excellent low-temperature gas separation performance at −30 °C, making them attractive for aggressive gas separations.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
MACROMOLECULES
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2024
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IF 5.1
Yuxuan Zhao,Jiangzhou Luo,Min Chen,Jun Hu,Honglei Ling,Xueping Zong,Song Xue
Herein, we developed a new diamine monomer termed TA-BOC that features a tert-butoxycarbonyl (t-Boc) protected group. This t-Boc group could shield one of the reactive amine sites present in the commercial tris(4-aminophenyl)amine (TAPA) monomer. Then, this difunctional TA-BOC analogue is employed as a comonomer alongside TAPA and 6FDA to regulate the cross-linking density of polyimide material by varying the molar ratio of TAPA to TA-BOC. Moreover, due to the bulky steric hindrance of the t-Boc group, we attempted to remove the t-Boc group via thermal treatment to create more microporosity within membranes. Therefore, because of the synergistic effect of reduced cross-linking density and heat treatment, the gas separation performance of the prepared membranes is greatly improved. Furthermore, the presence of trifunctional TAPA monomer in the network structures significantly enhances the membrane’s resistance to plasticization. For instance, 6F-TA:TA-BOC(1:3)-450 has a high CO2 permeability of 865.3 Barrer and an excellent CO2/CH4 selectivity of 41.8, meanwhile its CO2 plasticization pressures exceeding 35 bar. These values surpass the 2008 Robeson upper bound,, indicating its great potential for efficient gas separation processes. We expect that this study will provide new perspectives for the reasonable design of network polyimide membranes possessing an enhanced gas separation performance and strong plasticization resistance.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2023
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IF 9.5
Zhenyuan Li,Tianliang Han,Wei Lai,Jie Ma,Yang Zhang,Qi Wu,Can Wang,Chunfa Liao,Shuangjiang Luo
Herein, we develop and investigate the performance of defect-free hollow fiber membranes (HFMs) based on a novel 6FDA-mPDA 0.65 -DABA 0.3 -TFMB 0.05 copolyimide for helium separation from multi-component natural gas. The copolyimide is synthesized using a two-step condensation polymerization, and the hollow fiber membranes are fabricated using a dry-jet/wet-quench spinning approach. Thermal crosslinking of hollow fiber membranes is conducted to enhance plasticization resistance. The crosslinked membranes exhibit improved He selectivity (α(He/CH 4 ) = 259) compared to the pristine hollow fiber membrane (α(He/CH 4 ) = 210). Gas permeation tests are performed on the pristine and crosslinked hollow fiber membranes using pure-gas and mixed-gas at various pressures. The results demonstrate that the crosslinked membranes effectively resist plasticization even under high-pressure gas feeds containing CO 2 , light hydrocarbons, and heavy hydrocarbons. In contrast, the uncrosslinked membranes experience plasticization, dramatically decreasing selectivity. The findings provide valuable insights into the plasticization behavior of different impurity compounds in hollow fiber membranes and highlight the potential of thermal crosslinking as an effective strategy to improve the plasticization resistance of HFMs for He recovery. These defect-free and plasticization-resistant membranes hold promise for efficient He recovery from mixed-gas streams, offering a viable and energy-efficient alternative to traditional separation methods.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2021
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IF 8.742
Liang Wang,Xiang Guo,Feng Zhang,Nanwen Li
The polybenzimidazoles (PBI) has been employed as blends and macromolecular crosslinkers into bromomethylated polymers of intrinsic microporosity (PIM-Br) to prepare anti-plasticized gas separation membrane . Interestingly, the PBI showed excellent miscibility with PIM-Br probably due to the interaction between the benzimidazole and –CN groups, and thus a series of flexible, tough and transparent membranes were obtained by simply blending. After thermal treatment of the blending membrane, the crosslinked PIM-Br/PBI membranes with ionic and covalent crosslinking were achieved as confirmed by XPS results. Although the blending PIM-Br/PBI membranes showed the decreased gas permeabilities due to the lower gas permeability of PBI moieties, the increased gas permeabilities of PIM-Br/PBI membrane has been observed after crosslinking without significant sacrificing of selectivity. Moreover, higher crosslinking temperature induced the higher gas permeability. The PIM-Br/PBI membrane having PBI content of 5 wt% treated at 300 °C has a CO 2 permeability of 3313.7 Barrer which is much higher than that of the PIM-Br/PBI blending membrane (1645.3 Barrer) probably due to the formation of more open matrix in membrane after crosslinking. However, comparable CO 2 /CH 4 selectivity of ~13 were observed for all of the crosslinked membranes. Importantly, both of the blending and thermal crosslinking between PIM-Br and PBI resulted in the excellent CO 2 anti-plasticization ability of the membrane. Particularly, a single gas plasticization pressure as high as more than 600 psi and mixed-gas plasticization resistance for crosslinked PIM-Br/PBI have been observed. This value is much higher than that of the pristine PIM-Br membrane (100 psi).
研究领域:
材料科学
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化学工程
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DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2025
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IF 9
Ning Zhang,Yingmei Meng,Zhiying Li,Chuanlong Jin,Junjiang Bao,Xiaopeng Zhang,Gaohong He
High free-volume microporous membranes constructed by intrinsically microporous polymers (PIMs) are up-and-coming in efficient carbon capture, but their practical applications are limited by plasticization and physical aging issues. This work we proposed a CO 2 -solution-compensated cross-linking strategy to construct microporous membranes with both crosslinking network and enhanced CO 2 solubility via the Hoffmann alkylation reaction between the bromomethylated PIM matrix and Ethylenediamine (EDA) only at 80 °C. The enhanced CO 2 solubility could compensate the reduced CO 2 diffusion by the crosslinking network. Accordingly, the crosslinked microporous membranes with CO 2 -solubility compensation achieved a superior decarbonization from natrual gas (CO 2 permeability of 898.9 Barrer, CO 2 /CH 4 separation factors of 204.1) surpassing the 2019 Robeson upper and excellent anti-plasticization (plasticizing pressure up to 0.8 MPa) and anti-aging (CO 2 permeability loss < 10 % after 30 days) performance. The CO 2 -solubility-compensation crosslinking strategy will promote the development of high-performance microporous membrane for efficient decarbonization.
研究领域:
材料科学
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环境工程
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DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2023
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IF 8.6
Yang Jiao,Qi Wu,Wei Lai,Hongyan Liu,Haitao Zhang,King Lun Yeung,Shuangjiang Luo
Polybenzimidazole membranes with excellent size-sieving and plasticization resistance have attracted extensive attention for helium recovery from natural gas. Herein, we present a novel approach to fabricating polybenzimidazole membranes with exceptional gas selectivities and enhanced plasticization resistance. The strategy involves in-situ crosslinking of triptycene-containing polybenzimidazole membranes using 1,3,5-benzenetricarbonyl trichloride as the crosslinking agent. The crosslinking process tightens the polymer chains, resulting in reduced inter-segmental distance and fractional free volume, which significantly boosts the He/CH 4 and He/N 2 selectivities compared to non-crosslinked triptycene-containing polybenzimidazole membranes. The TPBI@CL 24 membrane exhibits a high mixed-gas He/CH 4 selectivity of 465 under a ternary 0.3:49.4:50.3 He/CO 2 /CH 4 (v/v/v) mixture at 100 PSIA and 35 °C. Moreover, the microporosity is feasibly tailored by controlling the crosslinking degree. Notably, the TPBI@CL x membranes demonstrate remarkable plasticization resistance under high-pressure three-component mixed-gas feed. The TPBI@CL 24 membrane experiences only a 9 % decrease in the mixed-gas He/CH 4 selectivity when the feed pressure increases from 100 to 500 PSIA at 35 °C, rendering the TPBI@CL x membranes with versatile separation performance applicable for industrial He recovery from natural gas.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2025
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IF 9
Yijun Liu,Yongchao Sun,Fake Sun,Hongjin Li,Jianyu Guan,Lu Bai,Zeyuan Gao,Tianyou Li,Fangxu Fan,Gaohong He,Canghai Ma
Ester-crosslinking has proven to be an effective strategy for enhancing gas selectivity and CO 2 -induced plasticization resistance. However, achieving ester-crosslinked membranes that surpass the 2019 CO 2 /N 2 upper bound remains a significant challenge. To address this, we used polymer of intrinsic microporosity (PIM-1) as a precursor, followed by hydrolysis to prepare PIM-COOH. Subsequently, 1,4-butylene glycol was employed as a crosslinker to react with PIM-COOH, forming M-PIM, which is then thermally crosslinked at different conditions. The ester-crosslinked membrane treated at 250 °C for 8 h demonstrated a CO 2 permeability of 7184 Barrer, with a selectivity of 36.7 for CO 2 /N 2 and 30.4 for CO 2 /CH 4 , both surpassing the 2019 upper bounds. Additionally, the ester-crosslinked membrane demonstrated resistance to CO 2 -induced plasticization even at a test pressure of 35 bar. These results suggest that esterification and crosslinking modification significantly enhance both the gas separation performance and plasticization resistance of PIM-1 membranes. The approach presented in this work provides a promising pathway for designing high-performance membranes that exceed the 2019 CO 2 separation upper bounds and improve resistance to CO 2 plasticization, with potential applications in natural gas purification and CO 2 capture.
研究领域:
材料科学
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化学工程
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环境科学
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产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2023
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IF 9.5
Yuchen Zhang,Junhao Xin,Guolong Huo,Zhiguang Zhang,Xiaowei Zhou,Jicheng Bi,Shuanyan Kang,Zhongde Dai,Nanwen Li
Polyimides (PIs) have gained recognition as highly desirable membrane materials for efficient CO 2 /CH 4 separation. However, the practical utilization of these materials has been impeded by the issue of the substantial susceptibility to plasticization when exposed to high-feed-pressure conditions. Although thermal cross-linking has been widely employed to enhance plasticization resistance in PI membranes, cross-linking will normally sacrifice CO 2 permeability. Thus, the advancement of PI membranes that exhibit both remarkable CO 2 permeability and exceptional plasticization resistance is highly desired. The current work designed a series of cross-linkable PIs with different polymer chain orientation degrees. Different from conventional PIs, by properly controlling the polymer chain orientation, the CO 2 permeability can be enhanced by 2.3 times without compromising the membrane plasticization resistance. Various techniques, including FTIR, WAXD , TGA , and DMA, were employed to thoroughly characterize the obtained membranes. These characterizations verified that optimizing the polymer chain orientation constitutes an efficacious strategy to enhance the resistance of PI membranes against plasticization, while simultaneously preserving their CO 2 permeability. Additionally, the thermally cross-linked membranes exhibited good long-term stability during an 1100-h test.
研究领域:
材料科学
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化学工程
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膜分离技术
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产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2021
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IF 8.742
Lei Wu,Xiuling Chen,Zhiguang Zhang,Shan Xu,Canghai Ma,Nanwen Li
As a new class of membrane materials, Tröger's base (TB) polymers suffer from CO 2 -induced plasticization , which leads to a loss in their gas separation selectivity . To address this challenge, we describe a new approach for enhancing their plasticization resistance by ring-opening a TB polymer to establish hydrogen bonds between polymer chains. The ring-opened membranes, called TB-OR, exhibit H 2 /CO 2 and H 2 /CH 4 selectivities of 5.1 and 186.7, respectively. High-pressure CO 2 feed measurements reveal that the TB-OR membranes possess better plasticization resistance than untreated TB polymers. The increased plasticization resistance is likely due to hydrogen bonds formed between –N-H groups and N atoms in TB-OR polymers, which reduce the polymer chain mobility and CO 2 -induced swelling of polymers. The design principles open a new route for making molecularly-selective membranes with significantly enhanced CO 2 plasticization resistance that are potentially useful for CO 2 separation and hydrogen purification.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
危险品化学品经营许可证（带存储）