JOURNAL OF MATERIALS SCIENCE
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2020
·Vol. 55
·期 34
·16158-16170
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IF 3.553
Li Menglin,Sheng Lei,Zhang Hui,Yang Yang,Xu Rong,Bai Yaozong,Song Shangjun,Liu Gaojun,Wang Tao,Huang Xianli,He Jianping
Abstract In order to solve the shortcomings of the current traditional commercial polyolefin microporous membranes with worse thermostability at high temperature, polyimide (PI) nanofiber membranes prepared by electrospinning are promising separators for lithium ion batteries that operate at high temperatures. This preparation includes the forming process of poly(amic acid) (PAA) fibers membrane and thermal-imidization process. In this study, we design the experiment of thermal-imidization for PAA fibers to improve the mechanical strength and the electrochemical performance of the obtained PI nanofiber membrane. It is found that the degradation phenomenon and the crosslinking function occur after the imidization during the heat treatment. The mechanical strength of PI nanofiber membrane gets improved with new crosslinking system after being heat-treated at 350 °C. LiCoO 2 /Li cells based on such PI nanofiber membranes exhibit excellent cycle performance (300 cycles) and rate performance (even at high rates of 6 C), better than those employing polyolefin microporous membranes. Graphic abstract During the heat treatment of polyamic acid, a thermal imidization process will occur. At the same time, different heat treatment temperatures will lead to differences in the degree of imidization and the structure of the fiber membrane material. It is important to understand the thermal imidization process. The effect of thermal imidization temperature on the performance of the electrospun polyimide lithium ion battery separator is studied. The experimental results show that although the degree of imidization is decreased by the heat treatment at 350 °C, it has better cycle performance (300 circles) and rate performance (even at high rates of 6 C).
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高影响因子
ACS Applied Materials & Interfaces
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2020
·
IF 8.758
Fan Xie,Yafang Wang,Longhai Zhuo,Fengfeng Jia,Doudou Ning,Zhaoqing Lu
Benefiting from its superior thermal stability, polyimide (PI) fiber-based composites have attracted wide attention in the field of high-temperature filtration and separation. However, the trade-off between filtration efficiency and pressure drop of traditional PI filters with single morphology and structure still remains challenging. Herein, the electrospun PI high-temperature-resistant air filter was fabricated via thermal-induced phase separation (TIPS), employing polyacrylonitrile (PAN) as a template. The PI nanofibers exhibited special wrinkled porous structure, and the filter possessed a high specific surface area of 304.77 m2/g. The removal of PAN changed the chemical composition of the fiber and induced PI molecules to form complex folds on the surface of the fiber, thus forming the wrinkled porous structure. Additionally, the wrinkled porous PI nanofiber filter displayed a high PM0.3 removal efficiency of 99.99% with a low pressure drop of 43.35 Pa at room temperature, and the filtration efficiency was still over 97% after being used for long time. Moreover, the efficiency of the filter could even reach 95.55% at a high temperature of 280 °C. The excellent filtration performance was attributed to the special wrinkled porous surface, which could limit the Brownian motion of PMs and reinforce the mechanical interception effect to capture the particulate matters (PMs) on the surface of the filter. Therefore, this work provided a novel strategy for the fabrication of filters with special morphology to cope with increasingly serious air pollution in the industrial field.
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PubMed
高影响因子
NEW JOURNAL OF CHEMISTRY
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2020
·Vol. 44
·期 28
·12068-12078
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IF 3.288
Hongtao Liu,Huafeng Tian,Yuanyuan Yao,Aiming Xiang,Haisong Qi,Qiangxian Wu,A. Varada Rajulu
Graphene oxide (GO) plays an important role in improving the mechanical properties and flame resistance of materials. In this work, polyimide (PI) composite foams were in situ generated by introducing modified GO based on a novel method. GO was modified by the interaction of its surfactant groups with dopamine (Do) using noncovalent bonds, to facilitate its dispersion in the PI matrix. The π–π conjugation was confirmed between GO and Do. Chemical interactions occurred between GO and PI through the reaction between the active groups on GO and –NCO of isocyanates. The resulting PI composite foams were characterized for their morphological, structural, mechanical, thermal and flame retardant properties. The cell structure of PI composite foams was uniform. Meanwhile, the compressive strength of composite foams significantly increased from 130 kPa to 163 kPa, resulting in a distinct enhancement in mechanical properties. The thermal stability of the composite foams was highly enhanced by GO as evidenced by the decreased mass loss during the maximum decomposition stage and increased residue at 800 °C. Furthermore, the values of limited oxygen index (LOI) of PI foams increased from 42.0% to 44.5%, while the PI composite foams exhibited self-extinguishing property. Therefore the modified GO dramatically improved the mechanical, thermal and flame resistance properties of PI foams.
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高影响因子
PROGRESS IN ORGANIC COATINGS
·
2020
·
IF 4.469
Shengguo Zhou,Wentao Li,Wenjie Zhao,Qunfang Li,Chao Liu,Zhiwen Fang,Xiulei Gao
In this work, hybrid phase and blend phase composed of carbon nanotube (CNT) and fluorinated graphene (FG) were doped into pure polyimide via a solution doping method to improve the tribological properties of polyimide. The effect of the hybrid phase and blend phase on mechanical and tribological properties of polyimide (PI) composite coatings were systematically investigated. The results showed that there was a much stronger interfacial interaction to enhance the mechanical properties of PI composite coating modified by the blend phase. The tensile strength increased by 46 %, hardness increased by 43 %, and storage modulus increased by 96 % at room temperature. The significantly enhanced mechanical properties can provide plenty of energy to resist wear for PI composite coating, and thus resulting in a 61 % reduction in wear rate. In addition, due to the lubricating properties imparted by the hybrid phase, the coefficient of friction (COF) of PI composite coating modified by hybrid phase was reduced by 13 %, showing the best anti-friction performance.
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高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2020
·
IF 7.183
Shuge Peng,Yamin Chen,Xiaopan Jin,Weiwei Lu,Minglei Gou,Xuefeng Wei,Jingpei Xie
To take advantage of Ag NPs‒enhanced membrane properties, how to slow the release of silver ions from membrane surface is the key. In this study, to enhance silver stability, half encapsulated Ag NPs by a loosely polyimide (PI) were covalently grafted onto ceramic membrane (CM) via in-situ reduction during thermal imidization. Various techniques were used to characterize the micro‒structure, pore size distribution , surface tension, and Zeta potential of the polyimide‒silver nanoparticle‒ceramic composite membrane (PI–Ag/CM). The antibacterial activity was assessed with fluorescent imaging method. The stability of silver was evaluated by static immersion and dynamic filtration tests. The anti‒biofouling performance was evaluated using bovine serum albumin (BSA) and E. coli as the model foulants, respectively. The results showed that the Ag NPs with the size of 50–80 nm were uniformly embedded on the surface of the grafted PI, which endowed the PI‒Ag/CM with improved silver stability, antibacterial activity, and anti‒biofouling performance simultaneously. This study demonstrated a new pathway for the modification of CM‒based and other inorganic membranes with lasting anti‒biofouling performance in water treatment.
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高影响因子
MATERIALS & DESIGN
·
2020
·
IF 6.289
Hong Ruan,Qiu Zhang,Weiqiang Liao,Yuqi Li,Xiaohua Huang,Xu Xu,Shaorong Lu
Developing self-lubricating composites with excellent tribological, thermal, and mechanical properties is a key aspect to solving the wear of materials . Herein, ionic liquid functionalized graphene (ILFG) were prepared by a π-π stacking interface design strategy. Then, a range of ILFG was filled into the polyimide (PI) matrix to prepare ILFG/PI composites (IGPI), and their tribological properties were investigated with a plate-on-ring apparatus under dry sliding conditions. When the content of ILFG was 0.4 wt%, the friction coefficient and specific wear rate of IGPI decreased by 38.2% and 25% compared to pure PI, respectively. A synergistic lubrication mechanism of ionic liquid (IL) and graphene was proposed for the formation of tribofilm under dry sliding. In addition, the mechanical and thermal properties of IGPI were also significantly improved by the synergy of IL and graphene. When the content of ILFG was 0.4 wt%, the tensile strength and modulus of IGPI composites increased by 51.9% and 56.5% relative to pure PI, respectively. The decomposition temperature of 5% weight loss (T 5% ) of IGPI with 0.4 wt% ILFG could reach 581.3 °C, an increase of 52.6 °C compared to that of PI, and the glass transition temperature improved by 14 °C.
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高影响因子
COMPOSITES PART B-ENGINEERING
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2019
·
IF 6.864
Syed Asadullah,Han Wu,Shiqi Mei,Deqiang Wang,Yongkang Pan,Dongliang Wang,Jun Zhao,Jie Wei
Polyimide (PI) may become a promising biomaterial for dental and orthopedic application due to its high mechanical strength , good biocompatibility and bio-stability as well as modulus of elasticity similar to the bone of human body. In this study, bioactive tantalum pentoxide (Ta 2 O 5 , TO)/polyimide (PI) composites (TPC) were fabricated by blending modification through a process of cold-pressing and sintering. The results revealed that the compressive strength , thermal stability, surface roughness , hydrophilicity and surface energy of TPC were significantly enhanced with the increase of TO content. Moreover, apatite mineralization of TPC in simulated body fluid (SBF) was obviously improved, in which TPC with TO of 50 wt% content (TPC50) displayed the best bioactivity . Furthermore, the cellular responses (adhesion, proliferation and differentiation) of rat bone mesenchymal stem cells (rBMSCs) to TPC were obviously upregulated with the increase of TO content. The results demonstrated that the TO content in the composites remarkably affected not only physical-chemical properties but also the cells behaviors. It can be suggested that TPC50 with improved surface properties and bioactivity as well as good cytocompatibility would have great potential and prospect for dental and orthopedic applications.
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高影响因子
RSC Advances
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2019
·Vol. 9
·期 14
·7706-7717
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IF 3.049
Shuangshuang Yue,Baoquan Wan,Yunying Liu,Qiwei Zhang
In this work, reduced BaTiO3 (rBT) particles with a large number of defects sintered in a reducing atmosphere (95N2/5H2) were introduced into polyimide (PI) matrix without using any modifier or surfactant components. The rBT/PI composite films fabricated by an in situ polymerization method showed significantly enhanced dielectric constant and energy storage density. The dielectric constant of the rBT/PI composite with 30 wt% rBT reached up to 31.6, while maintaining lower loss (tg δ = 0.031@1000 kHz) compared to pure PI (εr = 4.1). Its energy storage density (9.7 J cm−3 at 2628 kV cm−1) was enhanced by more than 400% over that of pure PI (1.9 J cm−3 at 3251 kV cm−1), and was greater than the energy density of the best commercial biaxially-oriented-polypropylenes (BOPP) (1.2 J cm−3 at 6400 kV cm−1). The energy storage efficiency was around 90% due to the linear dielectric performance of rBT/PI composite films. The improved dielectric constant and energy storage density could be attributed to the combined effect of the interface interaction between two phases and the surface defects of rBT induced by the reducing atmosphere. Therefore, rBT/PI composite films with high dielectric constant, energy storage density and storage efficiency may have potential applications in the preparation of embedded capacitors.
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高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
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2018
·Vol. 56
·期 18
·2115-2128
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IF 2.588
Zhiming Mi,Zhixiao Liu,Chunbo Wang,Yuhan Liu,Changjiang Zhou,Daming Wang,Xiaogang Zhao,Hongwei Zhou,Yumin Zhang,Chunhai Chen
To develop colorless and soluble polyimide films, cis -hydrogenated bisphenol A ( cis -HBPA) was successfully separated from HBPA isomers, and two novel monomers containing cis -HBPA unit, 4,4 ′ -(4,4 ′ -isopropenylbicyclohexyloxy) diphthalic anhydride (HBPADA) and 4,4 ′ -(4,4 ′ -isopropenylbicyclohexyloxy) dianiline (f) were designed and synthesized. PI–(1 – 5) were achieved from HBPADA and five kinds of aromatic diamines and PI – 6 from HBPADA and semiaromatic diamine f via a two-step thermal imidization. All the polyimides could afford flexible, tough, and transparent films with transparency as high as 86% at 450 nm. Surprisingly, the polyimides containing cis -HBPA unit exhibited excellent solubility not only in polar solvents such as N, N -dimethylacetamide, but also in low boiling solvents such as chloroform and dichloromethane. Additionally, analogues aromatic PI – 7 derived from 4,4 ′ -(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) and 2,2-bis(4-aminophenyl)hexafluoropropane (e) was obtained for comparison with PI–(1 – 6) on aspects of thermal, mechanical, soluble, optical, electrical, and morphological properties. The structure-property relationships of PI–(1 – 7) were investigated in detail. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56 , 2115–2128
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高影响因子
ACS Applied Electronic Materials
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2019
·
IF 0
Nan Zhang,Chun Huang,Shangshang Wan,Ling Kang,Menghan Hu,Yonghua Zhang,Xing Wu,Jian Zhang
An easy-to-fabricate, high-performance, and ultrabendable heater is always essential for the development of flexible devices such as gas sensors. Currently, most of the flexible heaters involve vacuum facilities or special inkjet printers/inks, which leads to complex processes and high fabrication cost. In this work, an innovative polymeric metalization technique was developed on polyimide substrate: in addition to the tunable electrical properties, Ag thin films obtained through the low-temperature solution-based process, the so-called surface modification and ion exchange (SMIE) process, could provide enhanced interfacial adhesion and mechanical stability. With a carbon ink as a masking layer, generated by a common home-/office-use inkjet printer, more than 400 patterned flexible heaters can be batch-fabricated on an A4 size polyimide conveniently. The results indicate that the heaters exhibit good electrical properties as well as superior bending stabilities. For the heaters with dimension of 1 cm × 1 cm, under an applied voltage of 20 Vdc, the maximum temperature achieved is 300 °C. Both the response time and recovery time are less than 15 s. The heaters can bear more than 1200 times bending cycling with a relative resistance change ratio of 0.11%. The developed technology is compatible with current batch fabrication processes such as roll-to-roll and can be employed to develop flexible heaters with high mechanical stability in the future.
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JOURNAL OF MEMBRANE SCIENCE
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2015
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IF 5.056
Jinchao Li,Yaping Zhang,Shuai Zhang,Xiaodong Huang
We report the fabrication and properties of high performance and inexpensive composite membranes of sulfonated polyimide (SPI) and sulfonated molybdenum disulfide (s-MoS 2 ) for the vanadium redox flow battery (VRFB) application. Scanning electron microscopy (SEM) images reveal the uniformity of SPI/s-MoS 2 membrane. Both EDS and XRD results verify the existence of s-MoS 2 in SPI/s-MoS 2 membrane and show the interaction between SPI and s-MoS 2 . The physico-chemical properties of as-prepared SPI/s-MoS 2 membrane, including water uptake and ion exchange capacity, etc. are evaluated and compared to those of SPI, SPI/MoS 2 and Nafion 117 membranes, respectively. The SPI/s-MoS 2 membrane possesses increased proton conductivity and reduced vanadium ion permeability than pure SPI membrane, and it has the highest proton selectivity (2.24×10 5 S min cm −3 ) among all membranes. The VRFB with SPI/s-MoS 2 membrane presents a higher coulombic efficiency ( CE ) and energy efficiency ( EE ) compared with Nafion 117 at the current density ranging from 20 to 80 mA cm −2 . The SPI/s-MoS 2 membrane shows a longer discharge time (193 h above 0.8 V) than Nafion 117 (72 h). Moreover, the SPI/s-MoS 2 membrane exhibits stable operation performance up to 500 cycles with no significant decline in CE and EE . All experimental results confirm that the SPI/s-MoS 2 membrane is suitable for use in VRFB.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2016
·Vol. 133
·期 28
·
IF 1.866
Baoming Li,Zhiyin Wu,Li Lin
A novel organosoluble polyimide (PI) with pyrimidine ring in the main chain was synthesized by chemical and thermal imidization, respectively, from 3,3′,4,4′-benzophenone tetracarboxylic dianhydride and 2,4-diamino-6-chloropyrimidine as raw materials and its molecular structure, solubility, UV–visible absorption characteristic, crystallinity, thermal stability, electrochemical behaviors, and mechanical properties were also studied. It was found that the introduction of pyrimidine ring in the main chain could increase the solubility of PI in polar aprotic solvents at room temperature and 60 °C, respectively, because of its molecular main chain with asymmetric structure and two polar N atoms in pyrimidine ring. Furthermore, PI had strong optical absorption peak intensity, excellent thermal stability, good redox reversibility, especially outstanding mechanical properties, which were conductive to its potential applications in adhesives, polyelectrolyte, separation membrane, and so on. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43680.
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