POLYMER
·
2019
·
IF 3.771
Zuolin Wu,Baochun Han,Chunhua Zhang,Danyang Zhu,Zhenghua Yang
Highly hydrophobic fluorinated polyimide aerogels were successfully prepared using a mild sol-gel method at room temperature from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2′-bis(trifluoromethyl)- 4,4′-diaminobiphenyl (TFDB), and cross-linked with 2,2′,7,7′-tetraamino-9,9′-spirobifluorene (TASBF). The obtained polyimide aerogels had low bulky density (0.118–0.161 g/cm 3 ), high specific surface areas (440.6–606.7 m 2 /g), small pore diameter (17.08–44.89 nm) and excellent mechanical property. These polyimide aerogels also exhibited high thermal stability in both nitrogen and air atmosphere, and the 5% weight loss occurred at temperatures above 530 °C. The introduction of 6FDA into polymer structures enhanced the hydrophobicity of the prepared polyimide aerogels. After replacing 50 mol % of BPDA with 6FDA in the oligomer backbone, water contact angles of the aerogels increased from 104.5° to 126.5°, and water absorption decreased from 4.3% to 2.1%. The high hydrophobicity makes these polyimide aerogels good candidates for use as thermal insulators in harsh environments and other applications.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2017
·
IF 2.843
Zhigeng Chen,Haohao Huang,Shijing Yan,Zhanping Zheng,Shumei Liu,Yanchao Yuan,Jianqing Zhao,Yi Fu
A new approach to synthesize fluorine-containing graphene oxide (FCGO) was proposed, in which a less toxic reagent was used rather than fluorine gas or anhydrous hydrogen fluoride. The dielectric and mechanical properties of polyimide composites were improved by incorporating a small amount of FCGO. FCGO served as not only nanofiller to lower the dielectric constant of PI films but also inorganic toughening particles to improve the toughness of PI films. The dielectric constant of PI films with 0.6 wt % FCGO was decreased from 3.33 for pure PI to 2.34. In addition, both the tensile strength and Young’s modulus of PI films with 0.6 wt % FCGO were increased to 141 MPa and 4.95 GPa from 118 MPa and 2.81 GPa for pure PI, respectively. In addition, its tensile energy to break was enhanced to 31.6 MJ/m3 from 20.8 MJ/m3.
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Nanomaterials
·
2024
·Vol. 14
·期 17
·1388
·
IF 4.4
Tian Zhou,Yu Yuan,Luyi Xiao,Wei Ding,Yong Wang,Li-Ping Lv
Redox-active porous organic polymers (POPs) demonstrate significant potential in supercapacitors. However, their intrinsic low electrical conductivity and stacking tendencies often lead to low utilization rates of redox-active sites within their structural units. Herein, polyimide POPs (donated as PMTA) are synthesized in situ on multi-walled carbon nanotubes (MWCNTs) from tetramino-benzoquinone (TABQ) and 1,4,5,8-naphthalene tetracarboxylic dianhydride (PMDA) monomers. The strong π–π stacking interactions drive the PMTA POPs and the MWCNTs together to form a PMTA/MWCNT composite. With the assistance of MWCNTs, the stacking issue and low conductivity of PMTA POPs are well addressed, leading to the obvious activation and enhanced utilization of the redox-active groups in the PMTA POPs. PMTA/MWCNT then achieves a high capacitance of 375.2 F g−1at 1 A g−1as compared to the pristine PMTA POPs (5.7 F g−1) and excellent cycling stability of 89.7% after 8000 cycles at 5 A g−1. Cyclic voltammetry (CV) and in situ Fourier-Transform Infrared (FT-IR) results reveal that the electrode reactions involve the reversible structural evolution of carbonyl groups, which are activated to provide rich pseudocapacitance. Asymmetric supercapacitors (ASCs) assembled with PMTA/MWCNTs and activated carbon (AC) offer a high energy density of 15.4 Wh kg−1at 980.4 W kg−1and maintain a capacitance retention of 125% after 10,000 cycles at 5 A g−1, indicating their good potential for practical applications.
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PubMed
高影响因子
ELECTROCHIMICA ACTA
·
2017
·
IF 4.798
Yang Pu,Xiaodong Huang,Pan Yang,Yuqin Zhou,Sensen Xuan,Yaping Zhang
Branched sulfonated polyimide (bSPI) membranes based on three different non-sulfonated diamine monomers were fabricated for vanadium redox flow battery (VRFB) usage. Both FT-IR and 1 H NMR spectra confirm that bSPIs were successfully synthesized. TGA results show that bSPI membranes have good thermal stability. FESEM pictures indicate that the surface of membrane in contact with catholyte keeps better integrity than that in contact with anolyte after 500-time cycling charge-discharge test. The water uptake, ion exchange capacity, mechanical strength of bSPI membranes are larger than or close to those of Nafion 117 membrane, and bSPI membranes exhibit remarkably lower vanadium ion permeability compared with Nafion 117 membrane. In addition, bSPI membranes have outstanding chemical stability in contrast with linear SPI membrane in ex-situ degradation test. Further, the bSPI (BAPP) membrane displays the best chemical stability and highest proton selectivity (1.23 × 10 5 S min cm −3 ) among all bSPI membranes, thus it is seen as an optimum one for further single VRFB test. During 500-time cyclic charge-discharge test, the coulomb efficiency ( CE : 97.1 ∼ 99.7%) of VRFB containing bSPI (BAPP) membrane is higher than that containing Nafion 117 ( CE : 95.2 ∼ 98.6%) at 30 ∼ 120 mA cm −2 . The VRFB using bSPI (BAPP) membrane presents higher or comparable energy efficiency ( EE ) and capacity retention compared with that using Nafion 117 membrane at low or high current density. Based on the excellent physico-chemical properties and single cell performance together with much lower cost compared with widely used Nafion 117 membrane, the as-prepared bSPI (BAPP) membrane has great potential to be applied in VRFB.
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RSC Advances
·
2017
·Vol. 7
·期 34
·20742-20753
·
IF 3.108
Yuanshi Xin,Tongsheng Li,Fanglin Xu,Mingming Wang
Modified graphene/carbon nanotube (abbreviated GCNT) assemblies were prepared by chemical compounding from amino-functionalized graphene (abbreviated MG) and carboxyl-functionalized multi-walled carbon nanotube (abbreviated MCNT). Diverse hybrid structures, such as graphene-shelled CNT microspheres, graphene/CNT interlayers and CNT-coated graphene nanosheets, have been obtained by adjusting the reaction ratio of the two precursor particles. The as-prepared GCNTs were incorporated into polyimide (PI) matrix to yield GCNT/PI composites by in situ polymerization. The mechanical, thermo-mechanical and tribological properties of GCNT/PI composites were investigated and synergistic effects in terms of lubrication and wear resistance have been acquired. The friction coefficient and wear rate decreased by 29.3% and 75.8%, respectively, with only 0.5 wt% addition of GCNT14 (WMG/WMCNT = 1 : 4), compared to virgin PI. The results indicate that combinational structure of multidimensional assemblies has a great influence on the enhancement performance and tribological mechanism of nanocomposites.
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JOURNAL OF POLYMER RESEARCH
·
2014
·Vol. 21
·期 11
·1-10
·
IF 1.897
He Zihai,Dai Wen,Yu Jinhong,Pan Lulu,Xiao Xiane,Lu Shaorong,Jiang Nan
In this paper, we have fabricated thermotropic liquid crystalline with epoxy groups grafted AlN nanoparticles (LCE-g-AlN) and then incorporated these into polyimide (PI) matrix to obtain the composites. The structure of LCE-g-AlN was charactered by Fourier-transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analyses (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The morphology and thermal properties of composites were systematically investigated. The morphology of the PI/LCE-g-AlN composites performed by scanning electron microscopy (SEM) indicating a homogeneous distribution of LCE-g-AlN nanoparticles in the PI matrix. Moreover, the value of Young’s modulus and tensile strength of the PI composites was increased by 78.3 % and 22.7 % in comparison with neat PI, respectively. The value of storage modulus of the PI composites achieved 7897 MPa with the incorporation of 10 wt.%, which increase 159.6 % compared with the neat PI (3035 MPa).
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POLYMER COMPOSITES
·
2014
·Vol. 37
·期 3
·907-914
·
IF 1.455
Peijiang Liu,Zhengjun Yao,Lin Li,Jintang Zhou
Polyimide (PI) and chemical modified graphene oxide nanocomposite films are prepared by in situ polymerization from solutions of pyromellitic dianhydride and 4,4′-oxydianiline with various amount (0.5–2 wt%) of 3-aminopropyltriethoxysilane (APTS) functionalized graphene oxide (GO) sheets in dimethylacetamide. The APTS functionalized GO (GO-APTS) is a versatile platform for polymer grafting, improving excellent dispersion of GO in the PI matrix, and forming strong interaction with the PI matrix. The GO-APTS/PI nanocomposites exhibited improvement in mechanical and thermal properties by addition of a small amount of GO-APTS. With the addition of a small amount of GO-APTS (1.5 wt%) to PI matrix, mechanical properties with the tensile strength and Young's modulus improved by 45% and 15%, respectively. The thermal analysis showed that the thermal stability of PI was slightly enhanced by the incorporation of GO-APTS (1.5 wt%). This approach provides a strategy for developing high performance functionalized GO-polymer composite materials. POLYM. COMPOS., 37:907–914, 2016. © 2014 Society of Plastics Engineers
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Boya Su,Jing Yang,Chenxi Xiong,Jie Song,Jingwen Hu,Zejing Wei,Guang Huang,Ping Rao,Honglei Guo
Polyimide (PI) aerogels possess significant potential for various applications due to their outstanding mechanics and thermal insulation. However, a major drawback of these aerogels is their susceptibility to moisture, which not only compromises their insulative performance but also leads to an increase in weight. To address this issue, we have developed a moisture-resistance technique by incorporating a long-chain hydrophobic barrier at the ortho position relative to the imide groups to enhance the moisture-resistance of the PI aerogels. This approach involved using a series of diamines with hydroxyl groups strategically located at the ortho position of imide groups as reactants. The resulting PI aerogels demonstrated a significant improvement in water resistance, reducing water-uptake to merely one-tenth of that recorded in unmodified samples. Furthermore, the effectiveness of this hydrophobic modification was validated through molecular dynamics simulations, which indicated a diffusion coefficient of 4.41 × 10 −11 m 2 /s after modification. These findings represent a considerable advancement in developing effective methods for hydrophobic modification of PI aerogels, with potential applications in aerospace, electronic communications, and environmental protection.
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PubMed
高影响因子
MACROMOLECULES
·
2024
·
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.
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高影响因子
ACS Applied Polymer Materials
·
2024
·
IF 4.4
Jinhuan Li,Mengqi Huang,Wentao Gao,Kai Yao,Hongfang Ma
Graphene/polyimide composite aerogels (GPIs) were fabricated through a one-pot solvothermal method and then underwent heat treatment at 350 °C to obtain GPIs (350). GPIs (350) exhibits prominent electromagnetic-wave-absorbing properties. Specifically, the minimum reflection loss can reach −75.90 dB with a thickness of 3.75 mm, and the effective absorption bandwidth reaches 6.44 GHz with a thickness of 2.70 mm. The actual dosage of graphene oxide in the GPIs (350) absorbers is low to 3 wt %, showing high effectiveness in absorbing electromagnetic waves. Notably, GPIs (350) also displays excellent thermal stability up to 415 °C. Polyimide is proven to tune the electromagnetic properties and provide much graphene–polyimide interface. The composition of graphene and polyimide, the three-dimensional morphology, and post-heat treatment are the perfect match to guarantee excellent comprehensive electromagnetic wave absorption properties. The present work provides a much more facile and effective approach to fabricating electromagnetic-wave-absorbing materials with exceptional properties through tuning engineering polymers.
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高影响因子
POLYMER ENGINEERING AND SCIENCE
·
2025
·
IF 3.2
Lu Shen,Xinyue Jiang,Long Ni,Yinfu Luo,Mei Liang,Yunhua Yang,Shengtai Zhou,Huawei Zou
With the rapid development of science and technology, there is an increasing demand for lightweight materials with excellent electromagnetic interference (EMI) shielding and infrared stealth performance for space applications. In this study, a series of polyimide/silica (PI/SiO 2 ) aerogels were fabricated by blending, which were dried using supercritical CO 2 drying method. Then, PI/SiO 2 composite aerogels were carbonized to prepare carbon aerogels with superior thermal insulation and EMI shielding properties. The carbonized PI/SiO 2 aerogels contained mesopores which enhanced the interfacial thermal resistance and improved the thermal insulation performance by 69% when compared with those samples without SiO 2 . The presence of mesopores adjusted the impedance matching of carbon aerogels, which allowed more EM waves to enter inside of the aerogels and dissipate through multiple reflections, thereby achieving absorption-dominant EMI shielding performance. This study proposed a viable approach to preparing PI-based carbon aerogels with excellent infrared stealth and EMI shielding performance, which show promising applications in aerospace and related industries. Highlights The introduction of SiO 2 regulated the microstructure of carbon aerogels. The thermal conductivity of carbon aerogels reached as low as 0.10 W/mK with 3 wt% SiO 2 . The EMI performance of carbon aerogel was enhanced from 22.4 to 33.5 dB.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Yutao Hao,Daomin Min,Ziwei Gao,Di Zhang,Jinghui Gao,Yongbin Liu
Electric vehicles and renewable energy consumption have huge demands for high-performance polymer dielectric capacitors. However, the resistivity and breakdown strength of existing polymer dielectrics deteriorate significantly at high temperatures, reducing the energy storage density and charge-discharge efficiency of capacitors below service requirements. The charge transport and molecular chain motion characteristics in linear polymers determine their conductivity, breakdown, and energy storage properties, but the quantitative relationship between them is not clear. An in-situ polymerization method was used to prepare polyimide/Al 2 O 3 nanocomposites (PI/Al 2 O 3 PNCs). Experimental results show that the resistivity, breakdown strength, energy storage density, and charge-discharge efficiency of PNCs increase initially and then decrease with increasing doping content, peaking at 3 wt%. The discharged energy density of PI/Al 2 O 3 -3 wt% PNCs at 180°C is 207.52 % higher than pure PI. A conductance-breakdown-energy storage co-simulation model based on charge transport and molecular chain displacement was used to simulate the voltage-current, breakdown, and energy storage characteristics of PNCs. The simulation results are consistent with the experiments. Comparative studies between simulation and experiments show that the independent interface zone between nanofillers and PI hinders charge transport and molecular chain movement, reducing electric field distortion and molecular chain spacing, thereby improving high-temperature breakdown and energy storage performance of PNCs.
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危险品化学品经营许可证（带存储）