Journal of Materials Chemistry C
·
2023
·
IF 6.4
Hong Li,Xiyan Li,Jiali Yu,Yadong Li,Zhigang Wang,Feng Bao,Caizhen Zhu,Jian Xu
As ultra large-scale integration (ULSI) circuits develop quickly, traditional polyimide (PI) urgently needs modification due to its high dielectric constant, to make it meet the requirements of ULSI development. In this study, the o-hydroxy polyimide structure was introduced into the PI main chain, and it was confirmed that the thermal rearrangement reaction of o-hydroxy polyimide could increase the molar volume of PI. Based on this property, this study successfully prepared low dielectric polyimide resins and meticulously investigated the effect of the rearrangement ratio on the properties of PI, especially the dielectric properties. The results show that the Dk of PI decreases significantly and the glass transition temperature (Tg) increases significantly with the increase of rearrangement ratio. Among them, it is worth mentioning that PBO-40 has the best performance, presenting a low dielectric constant (Dk = 2.54@10 GHz), low dielectric loss (Df = 0.00585@10 GHz), high heat resistance (Tg = 315 °C, 5% decomposition temperature (N2) Td5% = 509 °C) and low water absorption (Ma = 0.65%). In conclusion, this study provides learnable strategies for the design of high-frequency dielectric PIs.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2024
·
IF 5.1
Fuwei Wang,Guoke Zhao,Yiqun Liu,Gongqing Tang,Peiyong Qin,Pei Li
Thermally rearranged (TR) polymers have good gas separation property, but the high TR temperature often caused pore collapsing and embrittlement of hollow fiber. We designed two copolyimides by reacting a TR-able 3,3′-diaminophenolphthalein (DAP), and two non-TR able diamines, 2,4,6-trimethyl-m-phenylenediamine (DAM) and diethyl-toluene diamine (DETDA) with hexafluoroisopropylidene diphthalic anhydride (6FDA) using azeotropic distillation. The bulky DAM and DETDA diamines and the hydrogen bonding provided by the OH groups of DAP enabled high glass transition temperatures of Co-PI-DAM and Co-PI-DETDA copolyimides so that the thermal cross-linking and TR reaction realized at sub-Tg. Moreover, compared with the 6FDA–DAP polyimide, copolymerization greatly improved the tensile strength from 35 to 75 MPa (Co-PI-DAM). The cross-linked TR polymers exhibited high separation performance to CO2/CH4 and were not plasticized by CO2 at 30 atm. The two copolyimides show great potential for fabricating TR hollow fiber membranes.
研究领域:
材料科学
·
化学工程
✓ 已验证
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
·
化学工程
✓ 已验证
DOI
高影响因子
COMPOSITES PART B-ENGINEERING
·
2021
·
IF 9.078
Bo-Wen Liu,Yu-Fei Lei,Xiao-Feng Liu,Li Chen,De-Ming Guo,Yu-Zhong Wang
The use of conventional flame-retardant elements such as Cl, Br, P for carbon-based polymers usually leads to the deterioration of smoke and toxic gas release, and possesses serious environmental and ecological issues. Herein, we proposed a facile strategy to largely improve the flame-retardant efficiency of an eco-friendly flame-retardant method. By simply tailoring the substitution position of the functional polymerization monomer , the corresponding copolymer exhibited extremely high flame retardancy , including a 59% lower peak heat release rate (pHRR), a 48% lower smoke density, a high limiting oxygen index (LOI) of 30%, and passed the UL-94 V-0 rating without dripping. More importantly, the para -substitution copolymer showed a much higher flame-retardant efficiency than the meta -substitution copolymer, for which the monomer content needed for UL-94 V-0 rating, high LOI value, and low smoke and toxic gas release largely decreased by 25%. The detailed mechanism and the different performance between the two copolymers were comprehensively investigated. The results first confirmed the “end-group-capturing” mechanism, then revealed that the different flame-retardant efficiency was owing to the different thermal rearrangement capability of the two functional monomers . The molecular-level mechanism revealed here provided a novel thinking for designing flame-retardant polymers.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Storage
·
2021
·
IF 6.583
Wenhao Xu,Yunhua Lu,Haijun Chi,Hongbin Zhao,Junyi Hu,Guoyong Xiao
In this work, the hydroxyl-containing polyimide(HPI) nanofibers were fabricated by the electrospinning of poly(amic acid)(PAA) derived from pyromellitic anhydride(PMDA) and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane(6FAP), followed by thermal imidization. After further thermal rearrangement from HPI to polybenzoxazole(PBO) and pyrolysis, the HPI-based carbon nanofibers(HPICNFs) were obtained with abundant nitrogen and oxygen doping content. The effects of PAA concentration, thermally rearranged time and carbonizing temperature on the electrochemical performance of HPICNFs were evaluated. When the PAA concentration was 20%, the thermal rearrangement time was 2 h and the carbonization temperature was 800 °C, the specific surface area and pore volume of the HPICNFs reached 1107.6 m 2 g −1 and 0.6204 cm 3 g −1 . Due to the abundant micro- and mesoporous structures, the HPICNFs exhibited a high specific capacitance of 263.9 F g −1 and excellent capacity retention rate about 75% from 0.5 to 10 A g −1 . After 10,000 charging and discharging cycles, the capacitance retention of the symmetrical coin cell was maintained at about 99.82%, indicating superior long-term charging-discharging cycle stability. Additionally, a light-emitting diode was successfully lighted up by the three coin cells. Thus, this work provides a facile way to prepare the HPICNFs by thermal rearrangement and carbonization, which are expected to be used as high-performance electrode materials for supercapacitors.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Jingfa Zhang,Yongchao Sun,Fangxu Fan,Qizheng Zhao,Gaohong He,Canghai Ma
Thermally rearranged (TR) polymers have seen a growing role in gas separation membranes . Further exploitation of TR membranes with enhanced mechanical properties and gas separation performance are urgently demanded. Herein, a new series of TR polymers incorporating rigid triptycene units were prepared containing amino-functionalized neighbored benzene propellers and thermally rearrangeable o-hydroxy groups. The resultant TR membranes exhibit increased chain d-spacing and gas permeability with the increase of thermal arrangement temperatures. Moreover, the presence of triptycene enhances the mechanical strength of TR polymers due to the π-π stacking effect of triptycene moieties. The 400 °C TR polymer 6FDA-6FAP:DAT(2:1) displays a H 2 permeability of 345.3 Barrer with a H 2 /CH 4 selectivity of 83.6, 440% and 118% higher than the precursor, respectively, exceeding the latest Robeson upper bound. The design principle of TR membranes in this work provides an alternative route for the development of mechanically robust and high performance membranes with potentials for energy efficient gas separations.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
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
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Min Chen,Jiangzhou Luo,Honglei Ling,Xueping Zong,Song Xue
Developing membranes that combine excellent gas separation performance with robust resistance to plasticization is highly demanded for membrane separation but remains a challenge. Herein, a series of Zn 2+ functionalized poly(benzoxazole-co-imide) membrane was constructed via co-polymerizing (4,4′-hexafluoroisopropylidene) diphthalic anhydride (6FDA) with o-hydroxyl diamine 2,2′-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (BisAPAF) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) followed by thermal rearrangement (TR) and Zn 2+ modification processes. The TR conversion opened the polymer chains with larger d-spacing and higher BET surface area, thus, greatly increased the gas permeability . Meanwhile, the post Zn 2+ modification resulted in a huge improved selectivity because of the π-complexation reactions between Zn 2+ and CO 2 and the formation of a Zn 2+ coordination crosslinking network. As a result, due to the synergistic effect of TR and Zn 2+ modification, the overall gas transport properties of these newly developed membranes were greatly improved. Furthermore, the dual network structures that arise from the remaining network PI and the Zn 2+ coordination crosslinking contribute to the resultant membrane with excellent anti-plasticization capability. A represent membrane termed as PBOI-Zn 2+ -14h membrane exhibits great CO 2 /CH 4 separation performance, delivering a CO 2 permeability of 1048.1 Barrer and a CO 2 /CH 4 selectivity of 46.1 that is exceeded the 2008 Roberson limitation. Furthermore, this membrane possesses remarkable resistance to CO 2 -induced plasticization, withstanding pressures above 35 Bar. Overall, this study presents an effective way for constructing polymer membranes with both high gas separation performance and strong resistance to plasticization issue.
研究领域:
材料科学
·
膜分离技术
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Ao Tang,Huijie Nie,Jialin Zhang,Zhuo Chen,Jie Dong,Xin Zhao,Xiuting Li,Qingsong Xu,Qinghua Zhang
Breaking the trade-off effect between permeability and selectivity and preparing membranes with an excellent comprehensive separation performance is a relentless pursuit in the field of membrane separation technology. Herein, a new series of crosslinked thermally rearranged poly(imide- co -benzoxazole) membranes were successfully synthesized with greatly improved comprehensive gas separation performance. The o rtho -hydroxycopolyimide precursor was synthesized by reacting the newly designed dianhydride bearing the amide structure and thermally crosslinkable benzyl groups, N, N'-(2,4,6-trimethyl-1,3-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxamide) (MPADA), with hexaffuoroisopropylidene diphthalic anhydride (6FDA) and thermally rearrangeable diamine, 2,2-bis(3-amino-4-hydroxyphenyl)- hexafluoropropane (6FAP). Sequential thermal treatment at 375-450 °C under air and at 450-465°C under N 2 resulted in the benzyl-induced crosslinking reaction and thermal rearrangement (TR) reaction of ortho -hydroxyimide, respectively, within the precursor membrane. It demonstrates that the above reactions combined with the inherently existing interchain hydrogen bonding not only effectively expand the chain packing enabling microporous structure for gas transport but also introduce multi-scale microporosity via the unique dual crosslinked network that allows for molecular sieving capability in the resulting membrane. The resulting membranes exhibited a remarkable CO 2 permeability (341.2 Barrer) and ideal CO 2 /CH 4 selectivity (53), which outperformed some typical thermally rearranged polymer membranes and the state-of-the-art 2008 upper bound for CO 2 /CH 4 separation. More importantly, the resulting membranes demonstrated a superior anti-aging and high anti-plasticization property attributed to their highly stable molecular skeleton structure. This work provides a reliable route for constructing polymeric membranes with highly improved gas separation performance and stability.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2024
·
IF 4.4
Tian Yu,Qian Liu,Enkai Guo,Ning Qi,Feng Ren,Zhiquan Chen
Compositing metal organic framework (MOF) powder with a polymer substrate is an effective way to obtain an efficient gas separation membrane. However, the weak polymer–filler interaction usually leads to the formation of nonselective cracks in the composite material. Here, we report a MOF–polymer composite membrane with a continuous and dense MOF layer, which was synthesized by magnetron sputtering and vapor phase growth. A thermally rearranged poly(benzoxazole) (TR-PBO) membrane was converted from a hydroxy-polyimide precursor by a thermal rearrangement reaction, which was used as the polymer support of the composite membrane. An ultrathin ZnO seed layer was deposited on the TR-PBO support by magnetron sputtering technology, and then it was converted to a ZIF-8 layer by vapor phase growth. Scanning electron microscopy results confirm the formation of a dense, flat, and continuous ZIF layer with a thickness of about 450–600 nm. The ZIF-8 nanoparticles are uniform in size and evenly distributed. Furthermore, the attached ZIF layer significantly improves the gas selectivity of the composite membrane, which should be attributed to the sieving effect of the unique pore structure of ZIF-8. The method of magnetron sputtering combined with vapor phase growth is effective for improving the selectivity of the gas separation membrane and reducing the aggregation of MOF particles, which opens up a way for the design of flat and ultrathin gas separation composite membranes.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Fangxu Fan,Yongchao Sun,Lu Bai,Tianyou Li,Zeyuan Gao,Gaohong He,Canghai Ma
Thermally rearranged (TR) material has emerged as a focal point in gas separation membranes. However, further enhancing the gas separation performance of TR materials remains a key hurdle. In this study, fluorinated-cardo-based diamine (FFDA) was strategically incorporated into the polybenzoxazole structure to improve the gas selectivity. The size-sieving ability of the polymers was significantly enhanced through the interchain hydrogen bonding and π-π stacking induced by the cardo groups. Furthermore, the aromatic fluorine atoms in FFDA exhibited superior CO 2 adsorption capacity. As the thermal rearrangement progressed and the polybenzoxazole structure developed, pores with a diameter of approximately 3 Å were formed, leading to increased diffusion rate of CO 2 and H 2 . The TR400 °C membranes surpassed the 2018 CO 2 /CH 4 mixed-gas upper bound. Particularly, the 6FDA-FFDA/6FAP(1:1)-TR400 membrane achieved a CO 2 permeability of 185.3 Barrer and a CO 2 /CH 4 selectivity of 79.9—representing increases of 227.3 % and 37.5 %, respectively, compared to the precursor membranes. Moreover, the robust structure of the membrane demonstrated enhanced plasticization resistance, with no discernible plasticization observed under CO 2 /CH 4 mixed-gas conditions up to 20 bar. Our design approach paves the way for developing mechanically robust and highly selective TR membranes, with significant potentials for application in CO 2 separation under aggressive conditions.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2024
·Vol. 62
·期 15
·3439-3448
·
IF 3.9
Xu Liu,Qian Liu,Ning Qi,Zhiquan Chen
In this work, 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF) was used as the fixed diamine monomer, and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 4,4′-oxydiphthalic anhydride (ODPA), 3,3′,4,4′-biphenyltetracarboxylic diandhydride (BPDA) and pyromellitic dianhydride (PMDA) were selected as four different dianhydride monomers, respectively, to prepare the thermally rearranged polybenzoxazole (TR-PBO) gas separation membranes with different structures via a thermal rearrangement reaction at 450°C. The microstructure of TR-PBO membranes was investigated using X-ray diffraction and positron annihilation spectroscopy. All the TR-PBO membranes exhibit bimodal free volume structure, containing ultramicropores (<0.7 nm) and micropores (<2 nm) with size of 3.6–4.6 and 7.6–8.4 Å, respectively. As the steric hindrance of the bridging groups in the dianhydride monomers increases, the radius and number of pores in the membranes increases, leading to an increase in fractional free volume (FFV). The pure gas permeation test shows a positive correlation between gas permeability and FFV in the TR-PBO membranes, indicating that an increase in FFV is favorable for the diffusion of gas molecules. Particularly, the ultramicropores play a decisive role on the gas selectivity. All the TR-PBO membranes exhibit excellent gas permeaselectivity. Among them, the H 2 /CH 4 separation performance of APAF-6FDA and APAF-ODPA membranes approaches the 2008 Robeson upper bound, which is due to the high number of both micropores and ultramicropores. Our results demonstrate that the free volume structure of polymer membranes can be designed by selecting monomers with different structures and utilizing thermal rearrangement reactions, allowing for the preparation of gas separation membranes with high permeability and selectivity. Graphical
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）