JOURNAL OF MEMBRANE SCIENCE
·
2024
·
IF 8.4
Zhiguang Zhang,Xiaolong Ren,Guolong Huo,Xiaowei Zhou,Hao Chen,Hongjun Zhang,Shuanyan Kang,Xiuling Chen,Nanwen Li
6FDA-based polyimide air-dehumidification membrane has been considered as one of the most advanced technologies for the energy-saving heating, ventilation, and air-conditioning systems due to their excellent solubility and processing. Nevertheless, there are few reports about the effect of free volume and hydrophilic groups on dehumidification performance. Herein, we propose to tune the free volume and hydrophilicity of 6FDA-based polyimides by tuning the hydrophilicity/hydrophobicity of diamines and/or introducing of hydrophilic carboxylic acid groups, and thus to develop a system that would support high H 2 O/N 2 separation performance for dehumidification and retain excellent mechanical properties. It is found that 6FDA/mPDA membrane shows much higher H 2 O/N 2 separation performance (i.e., H 2 O permeability 12480 Barrer and H 2 O/N 2 separation factor of 13867) than that of the 6FDA/TFDB and 6FDA/DAM membranes even though its lower FFV. It is suggested that the FFV had a negligible effect on the H 2 O/N 2 separation performance. Although the introduction of highly hydrophilic –COOH groups could significantly increase the H 2 O/N 2 separation performance of hydrophobic 6FDA/TFMB and 6FDA/DAM membranes, the performance is still lower than that of 6FDA/mPDA membrane with similar hydrophilicity. In addition, we found that more –COOH groups to polymers can lead to the possible formation of hydrophilic/hydrophobic separation in membrane which will result in the rapid water vapor condensation and thus unstable air-dehumidification. Thus, the excessive hydrophilicity of 6FDA/mPDA-DABA showed a decreased H 2 O/N 2 separation performance compared with 6FDA/mPDA membrane. These results indicated that the excellent H 2 O/N 2 separation performance mainly depends on reasonable hydrophilicity of polyimide membrane without excessive hydrophilic groups and high FFV.
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
ACS Applied Materials & Interfaces
·
2026
·
IF 7.8
Rou Bao,Ximei Sun,Fayang Guan,Chengzhi He,Yu Cheng,Yun Shen,Lurong Xia,Lingyun Zhu
The regulation of electrolyte additives represents a straightforward and highly effective strategy for mitigating interface instability in lithium metal anodes, with the core of this approach lying in the rational design of molecular structures. We introduce a fluorinated macromolecular additive, 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), whose anhydride group and fluorine-rich characteristics enable the formation of a dense and robust LiF-rich solid electrolyte interphase (SEI). Remarkably, the addition of merely 0.02 wt % 6FDA significantly reduces the lithium nucleation overpotential from 234.6 mV to 80.5 mV, enabling uniform lithium deposition and suppressing side reactions. Intuitively, the Li||Li symmetric cells enable stable cycling for over 800 h at 0.5 mA cm–2. Assembled with an NCM88 cathode, the full cell achieved an initial Coulombic efficiency of 90.4%, and a capacity retention of 80.17% after 150 cycles at 1 C, significantly higher than the 30.87% of the traditional electrolyte. The rate behavior was markedly improved from 128.65 mAh g–1 to 170.22 mAh g–1 at 5 C. This study demonstrates that the 6FDA additive, a fluorinated macromolecular structure, considerably improves the electrochemical performance and cycling stability of lithium metal batteries through in situ interface engineering. This approach provides a promising strategy for the development of low-cost, high-safety lithium metal batteries.
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DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Peiyu Jia,Junjie Liu,Jingjing Kong,Mingming Hu,Ning Qi,Zhiquan Chen,Shan Xu,Nanwen Li
Two series of 6FDA-based co-polyimide membranes were synthesized by adding different diamine monomer containing special functional groups: APAF (containing OH) and DABA (containing -COOH). The ODA/APAF and ODA/DABA series were heat treated at 450 °C and 350 °C, respectively. Thermal rearrangement of polymer chain segments is confirmed in ODA/APAF membranes by infrared spectroscopy, while addition of DABA in ODA/DABA membranes causes decarboxylation crosslinking. Positron lifetime measurements reveal existence of ultramicropores in polyimides. The thermal rearrangement in ODA/APAF membranes induces remarkable increase in both size and number of ultramicropores and therefore increase in fractional free volume (FFV), but the crosslinking in ODA/DABA causes significant decrease in both size and number of ultramicropores. The increase in FFV is favorable for gas permeation, but too large size of the micropore drastically deteriorates the gas selectivity. Finally, the ODA/APAF(3:7) shows a high CO 2 permeability of 127.4 Barrer with CO 2 /CH 4 selectivity of 34.2, which surpasses the 1991 Robeson upper bound. Besides, the ODA/DABA(3:7) exhibits a H 2 permeability of 22.6 Barrer with H 2 /CH 4 selectivity of 256.8, which also exceeds the 1991 Robeson upper bound. Our results indicate that the gas permeability and selectivity of polymer membranes can be effectively adjusted by tailoring the ultramicropore structures, and positron can provide precise information about micropores.
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
·
2023
·
IF 8.6
Guozhen Liu,Renhao Li,Xi Chen,Long Cheng,Yu Liu,Gongping Liu,Wanqin Jin
Carbon molecular sieve (CMS) membranes with exceptional separation performance and scalable processing are promising for precise gas separation. However, their broad applicability is hampered owing to stability issues, mainly resulting from physical aging. Herein, we manipulate the pyrolysis temperature (550 °C, 650 °C and 750 °C) to regulate the gas transport properties and control the physical aging of CMS membranes derived from 6FDA-DAM polyimide. The morphology, chemical composition and pore size of the membranes were characterized using SEM, IR, XPS and XRD. Results demonstrated that the pore structure of CMS membranes shows densification with increasing the pyrolysis temperature, affording enhanced separation efficiency for gas pairs: H 2 /N 2 , H 2 /CH 4 , and CO 2 /CH 4 pairs based on the size-sieving effect. Moreover, the effect of aging is more considerable for membranes pyrolyzed at a higher temperature. In addition, the membrane subjected to pre-aging treatment via vacuum storage exhibit better, stable gas separation performance beyond the upper-bond for polymeric membranes. The separation mechanism of the CMS membranes reveals that gas permeation behavior is dominated by diffusion. Tailoring gas permeation and physical aging can provide an alternative approach to tune the gas transport properties of CMS membranes.
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
ACS Applied Engineering Materials
·
2026
·
IF 3.5
Zehui Yao,Xinhai Zhang,Yi Wang,Xiaozu Wang,Zhaohui Wang,Zhaoliang Cui
Polyimide (PI) membranes face a trade-off between permeability and selectivity, limiting their gas separation applications. To address this, we synthesized 6FDA-DAM/DABA(DAM:DABA = 3:2) PI and two-dimensional COF-1 nanofillers, fabricating hollow fiber mixed matrix membranes (MMMs) via dry-jet wet-spinning. Under optimized conditions (25 cm air gap, 50 °C spinneret temperature, 30 °C NMP coagulation bath), the 10 wt % COF-1 incorporated membranes achieved optimal performance: tensile strength of 15.34 MPa; H2 and CO2 permeances of 79.3 GPU and 54.3 GPU, and ideal selectivities of 187.9 for H2/CH4 and 128.7 for CO2/CH4, respectively. The results demonstrate that the incorporation of COF-1 modifies solvent exchange during spinning, necessitating targeted optimization of spinning parameters to coordinate membrane structure and performance.
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DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Guozhen Li,Zhihao Si,Shuai Yang,Yan Zhuang,Siyu Pang,Yuhui Cui,Jan Baeyens,Peiyong Qin
Mixed-matrix membranes (MMMs), consisting of nanoparticles and a polymeric matrix, have been proven high-efficiency separation media for gas separations. The interface engineering between the particles and polymeric matrixes is the key-point for MMMs to display an excellent separation performance. Herein, an amine modified ZIF-90 (ZIF-90-NH 2 ) is dispersed in 6FDA-Durene to prepare MMMs, the modified amino groups can form the hydrogen bonding with 6FDA-Durene to enhance the compatibility of ZIF-90-NH 2 and 6FDA-Durene. A 45 wt% ZIF-90-NH 2 /6FDA-Durene MMM demonstrated a high separation performance, surpassing the 2008 Robeson permeability-selectivity upper bounds. This satisfactory gas separation performance can be due to the intimate interactions between the 6FDA-Durene polymer and ZIF-90-NH 2 nanoparticles via abundant hydrogen bonding. Furthermore, the covalent linkage of ZIF-90-NH 2 with 6FDA-Durene can be driven by the tris(2-aminoethyl) amine (TAEA) vapor thermal modification method to realize the ring opening reaction, which further enhances the particles-polymer connection in the ZIF-90-NH 2 /6FDA-Durene-TAEA MMMs. Results show that the 45 wt% ZIF-90-NH 2 /6FDA-Durene-TAEA MMM exhibits a remarkably enhanced H 2 permeability of 487.0 Barrer with a H 2 /CO 2 selectivity of 35.8, which is 6.8 times higher than that of ZIF-90/6FDA-Durene-TAEA MMM. This strategy offers new prospects for membrane materials and opens a new way for the precise interface engineering of MMMs, and the resulting high performance for energy-efficient gas separations.
研究领域:
材料科学
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化学工程
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膜技术
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2023
·
IF 8.6
Haojie Li,Bingyu Zhao,Yuxiu Yu,Yaodong Liu
Good gas separation performance and anti-aging ability are important for the applications of carbon molecular sieve membrane (CMSM). In this work, silicon atoms in the form of siloxane-Cl are introduced into 6FDA-DABA type polyimide (PI) precursor membrane, and benzimidazoles (BI) is copolymerized into PI to effectively improve the compatibility between PI and siloxane-Cl. By varying the content of siloxane-Cl, the composite membrane changes from macro-phase separation to molecule level miscibility, which leads to the formation of silicon-rich interface layer and silicon molecule doping after high temperature pyrolysis, respectively. The residual silicon content in CMSM could be as high as 1 wt%. The high content silicon doped CMSM exhibits much improved H 2 permeability retention degree (3617 Barrer of H 2 permeability, 62% higher) and H 2 /CH 4 selectivity (138, 51% higher) as compared to control CMSM after 45 days of physical aging. This work proves that the incorporation of silicon in CMSMs in proper forms could significantly improve their molecular sieving and anti-aging performances; a higher content of residual silicon and molecule level doping are highly desired. The heteroatom doping is expected to pave a new way for finely tuning the micro-structures of CMSMs and improving gas separation performances.
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
·
2021
·
IF 8.742
Jingjing Kong,Junjie Liu,Peiyu Jia,Ning Qi,Zhiquan Chen,Shan Xu,Nanwen Li
Two kinds of polyimide membranes 6F-AP and 6F-AP/DA (APAF:DABA=3:2) were synthesized and heated between 300–450 °C to study the effect of thermal treatment on the chain structure and gas transport performance of membranes. Fourier Transform Infrared (FI-IR) and X-ray diffraction (XRD) measurements show that heating causes rearrangement of polyimide into rigid polybenzoxazole which prevents the effective stacking of polymer chains leading to the increase of d-spacing and fractional free volume. Positron annihilation results confirm the increase of both size and number of free volume due to the thermal rearrangement. The addition of DABA monomer into 6F-AP causes crosslinking during heating, which results in tightening of the rigid chain spacing of benzoxazole, thus leading to slight decrease in the size and number of free volume. The increase in fraction free volume induced by thermal rearrangement can significantly improve the gas permeability of 6F-AP series membranes, which increases from 16.2 and 3.9 barrer to 271.4 and 200.3 barrer for H 2 and CO 2 , respectively, after increasing the heating temperature from 300 to 450 °C. But this is accompanied by a decrease in gas selectivity due to the increase in free volume size. Finally, by careful tailoring the free volume structure through thermal rearrangement and crosslinking, the 6F-AP/DA polyimide treated at 400 °C exhibits a H 2 permeability of 196.4 barrer and a H 2 /CH 4 ideal selectivity of 90, which is above the 2008 Robeson upper bound. Our results indicate that by designing the functional groups of the reaction monomer plus appropriate thermal treatment, the microstructure of polyimide membrane can be effectively adjusted for high-performance gas separation.
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
EUROPEAN POLYMER JOURNAL
·
2023
·
IF 6
Yuan-Yuan Liu,Jian-Hua Cao,Yue Li,Ya-Kun Wang,Da-Yong Wu
In this work, we use 2-aminobenzimidazole and 2-aminobenzoxazole to end-cap colorless polymer, PAI TFDB-TPC-6FDA, in order to investigate methods for reducing the CTE value of products and their effects on other properties. Results show that, as the ratio of 2-aminobenzimidazole to the raw material, diamine TFDB, increases from 0:100 to 2:99, the CTE value of products gradually decreases from 20.0 to 12.9 ppm/K (a decrease of 36%). Nevertheless, the CTE value of products rebounds as the dosage of the end-capped groups exceeds this ratio. Among all the products obtained, PAI-1M film has the best overall properties: its CTE is 12.9 ppm/K, T d 5 is 518 ℃, T g is 366 ℃, T S is 191 MPa, T 430 is 85.1%, W A is 85.4% and C A is 0.8%. The two end-capped groups are of highly linear and rigid structures. They also help to enhance the hydrogen bonding between molecules, resulting in a decrease in d -spacing values. The results of molecular configuration simulation and calculation indicate that, using 2-aminobenzimidazole to end-cap the chains of PAI molecules is beneficial for suppressing the formation of the charge-transfer complexes (CTCs), and thereby offsetting impacts of the reduced molecular chain spacing on the transparency of films. Based on these two influencing factors, we confidently conclude that linear and rigid end-capped groups can effectively improve the dimensional stability and mechanical properties of PAI films without damaging their optical properties.
研究领域:
高分子科学
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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
Frontiers of Chemical Science and Engineering
·
2024
·Vol. 18
·期 4
·1-10
·
IF 4.3
Li Ying,Wang Lu,Xie Junyan,Dai Yong,Gu Xuehong,Wang Xuerui
Membrane gas separation is considered an energy-saving technique to extract He from natural gas due to no phase change and room temperature operation. However, the membrane performance was strongly limited by the trade-off between permeance and selectivity. Herein, novel 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)-2,2′-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF)-5-amino-2-(4-aminobenzene) benzimidazole (BIA) asymmetric membranes with a thickness of 300 nm were successfully prepared by the non-solvent induced phase separation method. The membrane performance was modulated by regulating dope solution compositions (e.g., tetrahydrofuran and polymer concentration). The ideal He/CH 4 selectivity was 124 and the optimized He permeance reached 87 GPU, beyond the current upper bound. He/CH 4 selectivity was 75 and He permeance was 73 GPU for the binary mixture feed containing 0.2 mol % He. The membrane showed good resistance to CO 2 and C 2 H 6 , which are the typical impurities in natural gas. The 6FDA-APAF-BIA membranes have good stability (> 160 h), which can provide great potential in He extraction from natural gas.
研究领域:
膜科学
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气体分离
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聚合物工程
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相分离
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节能分离
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材料科学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
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IF 8.6
Lu Wang,Ying Li,Liming Pu,Miao Yang,Hongsheng Lu,Xuehong Gu,Xuerui Wang
Helium extraction from natural gas is energy extensive since >95% feed stream needs to be liquefied in multi-cycles. Membrane gas separation is an energy-efficient alternative because of room temperature operation and no phase change. However, the practical application is significantly retarded by the limited permeation flux, which is mainly attributed to the thick selective layer. Herein, asymmetric 6FDA-APAF 0.5 -Cardo 0.5 copolyimide membranes with effective thickness of ∼ 200 nm were prepared by the one-step phase inversion method. The He permeance reached up to 120 GPU, one order magnitude higher than that of the free-standing one. The selectivity was 44 for He/N 2 and 67 for He/CH 4 binary mixtures. The performance surpassed 2019 upper bound and the benchmark membranes for He separation from N 2 or CH 4 . Meanwhile, the performance is resistant to the impurities of C 2 H 6 and CO 2 in the natural gas. Together with long-term stability (>200 h), the thin 6FDA-APAF 0.5 -Cardo 0.5 membrane would pave the way to He extraction from natural gas for practical application.
研究领域:
化学工程
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材料科学
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膜技术
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气体分离
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产品关联
DOI
高影响因子
HIGH PERFORMANCE POLYMERS
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2022
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IF 1.73
Qi Li,Sung S Park,Chang-Sik Ha,Shuai Yuan,Liyi Shi
In this work, a copolyimide (Co-PI) film with high transparency was prepared by the copolymerization of hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 2,2′-Bis(trifluoromethyl)benzidine (TFMB) and adamantane-1,3-diamine (DAA). The effects of DAA monomers on the optical, thermal, and mechanical properties of the co-PIs were discussed in detail. We found that the preparation of polyimide (PI) based on the combination of two dianhydrides and two diamines could obtain the co-PI film with excellent comprehensive performance due to the synergy between the -CF3 group, the aliphatic ring and the aromatic structure. Through the structure and composition optimization, the co-PI film with 1.30% DAA (Q3) has a Tg of 374oC, T5 higher than 530oC, T430 of 82% and the tensile strength higher than 145 MPa. These results indicate that the Co-PI films can be successfully utilized in the development of novel heat-resistant plastic substrates for the optoelectronic engineering applications.
研究领域:
聚合物科学
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材料科学
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光电子学
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DOI
高影响因子
危险品化学品经营许可证（带存储）