JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2023
·Vol. 34
·期 7
·1-8
·
IF 2.8
Xu Tao,Liu Huiping,Zhao Rongjun,Yuan Linjie,Zhu Zewei,Chen Xi,Hou Haoqin,Peng Xinwen
Polymer film capacitors do not meet the increasing demand of high-temperature (> 125 °C) applications with the rapid development of new energy. In particular, few polymer dielectrics can operate at high temperatures (> 250 °C). In order to develop high-temperature-resistant polymer dielectrics, a novel polyimide containing porphyrin units (PI-a) was prepared by using this diamine polymerized with 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BTDA). PI-a possesses high dielectric constant up to 9.04; however, its highly rigid backbone and low molecular weight affect other properties and applications. Here, high-performance polyimide dielectrics were developed by a highly scalable and low-cost strategy. The PI-a and PI-b which was prepared with 4,4′-diaminodiphenyl ether (ODA) and BTDA are mixed by proper design to improve dipolar polarization and intermolecular interactions among polymer chains. Consequently, such polyimide blend with the ratio of PI-a 40% displays an intrinsic giant permittivity of 6.68, low dielectric loss (< 0.05), the highest energy storage density (2.87 J cm −3 ), and possesses excellent mechanical property and excellent thermal stability. These obtained polyimide blends can extend applications of film capacitors at high temperature.
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JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Zhiguang Zhang,Xiaolong Ren,Guolong Huo,Shuanyan Kang,Zhenggong Wang,Nanwen Li
Fluorinated polyimides with biphenyl structure and –CF 3 with rigid chain structure exhibit great potential in membrane-based gas separation. However, the comprehensive separation performance of this type polyimides is not competitive as a gas separation material. Structure regulation is of great significance to improve the separation performance of polymer membrane. Few studies systematically investigated structure-property relationships in fluorinated polyimide structure. In this study, carboxylic groups are introduced into a fluorinated polyimide(6FDA-TFMB) via copolymerization with DABA diamine monomer . The hydrogen bond between –CF 3 group in TFMB and –COOH group in DABA is proposed to enhance chain segment rigidity and optimize polymer chain arrangement. WAXD results and FFV data indicate that inter-chain cavity of fluorinated polyimide could be finely tuned by adjusting molar ratio of TFMB and DABA in the copolyimide. The resulted copolyimide membranes thus demonstrate tunable gas permeation properties. Gas permeability of 6FDA-TFMB/DABA firstly increases and then decreases, and ideal gas selectivity continuously increases with increasing DABA molar ratio. Among the polyimides, 6FDA-TFMB/DABA(6:4) membrane demonstrated superior separation performance, e.g. CO 2 permeability of 135.6 Barrer and CO 2 /CH 4 ideal selectivity of 31.6, surpassing the commercial cellulose acetate and Matrimid membrane. Attributed to the optimized interchain interaction, the 6FDA-TFMB/DABA (6:4) membrane displays an optimized CO 2 plasticization resistance and physical aging in comparison with 6FDA-TFMB membranes. This study provides a guideline for controlling and optimize the performance of biphenyl fluorinated polyimide gas separation membrane .
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ACS Sustainable Chemistry & Engineering
·
2023
·
IF 8.4
Yuanyuan Zhu,Yunqiang Zhang,Shihang Jin,Mei Li,Hui Zhao,Jiaxi Cui,Laiying Jing
Lithium–sulfur batteries (LSBs) have broad application prospects in high density energy storage. Nevertheless, LSBs present serious safety concerns and rapid capacity decay due to the flammability and contractility of commercial separators at high temperatures and lithium polysulfide (LiPSs) dissolution. In view of this, a multifunctional modified separator is developed by combining a commercial polypropylene (PP) separator with a polyimide (PI)-Super P functional coating and a rigid nonflammable PI matrix. This PI/PP/PI-Super P separator provides multiple advantages: (i) strong physical blocking and chemical trapping/conversion ability for LiPSs, (ii) high flame-retardancy and dimensional stability, and (iii) superior electrolyte wettability and high efficiency lithium dendritic growth inhibition. As a result, the LSBs assembled with PI/PP/PI-Super P separators and pure sulfur cathodes exhibit an ultrahigh discharge specific capacity of 1611.8 mAh/g and excellent cycling performance (the average capacity attenuation within 100 cycles at 1 C is 0.469%) at 80 °C, which exceed the advanced results reported previously. More importantly, even when sulfur and organic electrolyte are adsorbed on PI/PP/PI-Super P, the modified separator still shows good flame retardancy. Additionally, this modified separator is also suitable for LSBs with high sulfur loading. This work offers an innovative design concept for safe and high-performance LSBs.
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JOURNAL OF POLYMER SCIENCE
·
2022
·Vol. 61
·期 6
·491-502
·
IF 3.046
Lidong Cao,Xingzhong Fang,Guofei Chen
High imidization temperature of polyimides (PIs) brings great restriction to the applications in electronic industry. In this study, N,N ′-carbonyldiimidazole (CDI), a novel low-temperature imidization accelerator with the unique dual function of catalyst and dehydrating agent, was researched to solve this problem. PIs synthesized from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4,4′-oxydianiline were researched as the main object on method A and method B, two preparation methods of PIs, by introduction of CDI, which was found that the PIs prepared by method A achieved complete imidization and basically had no residual CDI and N,N -Dimethylacetamide at 180 °C under vacuum, while the completely imidized PIs prepared by method B were also obtained at 40 °C. Even prepared at low temperature, the PI films with adding CDI both showed satisfactory thermal and mechanical properties, especially in reducing coefficient of thermal expansion. In addition, the universality of the reaction between CDI and poly(amic acid) were also verified by other soluble PI systems. All these results prove the superior performance of CDI in lowering imidization temperature, showing great potentials in low-temperature cured PIs. Graphical
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Energy & Environmental Materials
·
2022
·Vol. 6
·期 1
·e12427
·
IF 13.443
Baoquan Wan,Ming-Sheng Zheng,Xing Yang,Xiaodi Dong,Yuchao Li,Yiu-Wing Mai,George Chen,Jun-Wei Zha
Recyclability and self-healing are two most critical factors in developing sustainable polymers to deal with environmental pollution and resource waste. In this work, a dynamic cross-linked polyimide insulation film with full closed-loop recyclability is successfully prepared, which also possesses good self-healing ability after being mechanical/electrical damaged depending on the Schiff base dynamic covalent bonds. The recycled and self-healed polyimide film still maintain its good tensile strength ( σ t ) >60 MPa with Young's modulus ( E ) >4 GPa, high thermal stability with glass transition temperature ( T g ) >220 °C, and outstanding insulation property with breakdown strength ( E 0 ) >358 kV mm −1 , making it a very promising low energy consumption and high temperature resistant insulation material. The strategy of using Schiff base dynamic covalent bonds for reversible repairing the structure of high T g polyimides promotes the wider application of such sustainable and recyclable material in the field of electrical power and micro-electronics.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Zhiheng Zheng,Huan Liu,Dezhen Wu,Xiaodong Wang
Aiming to explore a high-efficient seawater desalination technique based on solar photothermal energy as the cleanest and most abundant renewable energy source, we developed a novel type of phase-change composites based on a polyimide (PI)/MXene hybrid aerogel as a supporting material and polyethylene glycol (PEG) as a phase change material. The introduction of Ti 3 C 2 T x MXene nanosheets as a high-efficient sunlight absorber not only significantly enhanced solar photothermal energy-conversion efficiency up to 87.28% for the aerogel/PEG composites, but also improved the volume capacity of the hybrid aerogels. This resulted in an extremely high PEG loading rate of up to 97.68 wt% and a high enthalpy efficiency of up to 95.16%. The hybrid aerogel/PEG composites also exhibit an outstanding thermal energy-storage capability under a high latent heat capacity of over 170 J·g −1 , high thermal cycle stability, good leakage-resistant performance, excellent thermal impact resistance, and good shape/form stability to deal with the use in seawater desalination. More importantly, the hybrid aerogel/PEG composites show a high seawater evaporation mass of 6.07 kg·m −2 , a high evaporation rate of 1.24 kg·m −2 ·h −1 under one-sun illumination, and a high evaporation efficiency of 50.6% when used in a solar-driven evaporation device. The PI/MXene hybrid aerogel/PEG composites developed by this work exhibit a great potential for application in sustainable seawater desalination.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Hao He,Qiang Liu,Shui-Dong Zhang,Hong-Bing Chen
In this study, polyimide (PI)/carbon fiber (CF) aerogel was fabricated via a freeze-drying method. The introduction of CF endows PI aerogels with good dimensional stability in the thermal imidization process. The resulting aerogel possesses excellent mechanical property (as high as 58.45 MPa) and good hydrophobic property (contact angle above 120°). The PI/CF aerogel also has very good radiation resistance, with a compressive modulus of 50.45 MPa even after 10 MGy irradiation, which is 86.53% of the initial modulus. These characteristics make the PI/CF aerogel very suitable for applications in radiation environment. Subsequently, a carbon aerogel with high temperature resistance and good mechanical properties was obtained by carbonization of the PI/CF aerogel. Its comprehensive property is comparable to traditional porous carbon-bonded carbon fiber composites.
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COMPOSITES SCIENCE AND TECHNOLOGY
·
2022
·
IF 9.879
Chen-yu Li,Ting Gu,De-xiang Sun,Xiao-dong Qi,Cheng-shou Zhao,Yan-zhou Lei,Yong Wang
With the rapid development of electrical equipment and integrated circuits, packaging materials with high heat dissipation capability are in great demand. Reducing the interfacial thermal resistance is still a great challenge in polymeric composites . Herein, surface-induced polyamide acid (PAA) polymerization on boron nitride nanosheets (BNNSs) was firstly achieved, and then the BNNS@PAA was introduced into the polymerization system of polyimide (PI). The dependence of microstructures and performances of the composites on imidization degree of BNNS@PAA was systematically investigated. The results show that there is an appropriate imidization temperature (120 °C), at which the composite with only 10 wt% BNNS@PAA exhibits high thermal conductivity (2.11 W/m·K), excellent mechanical properties (with tensile strength of 97.2 MPa and elongation at break of 19.8%), and good dielectric properties (with a discharged energy density of 3.67 J/cm 3 and a charge-discharge efficiency of 87.4% at the field of 300 MV/m).
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COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2022
·
IF 9.463
Yinan Zhao,Jiayun Chen,Xuejun Lai,Hongqiang Li,Xingrong Zeng,Changcheng Jiang,Qingtao Zeng,Kunquan Li,Zhengzhong Wu,Yunkun Qiu
The rapid development of intelligent fire protection technology puts forward higher requirements for the versatility and fire safety of aerogels . Herein, a multifunctional fire-retardant polyimide/MXene/Ag 2 Se nanowires (PMA) composite aerogel was fabricated via freeze-drying and dip-coating. The PMA aerogel demonstrated good strength and flexibility. The improved thermoelectric properties of the PM 1 A 1 aerogels were attributed to the energy filtration effect between the MXene and Ag 2 SeNW, which endowed the aerogels with accurate temperature sensing and sensitive, repeatable, and stable fire-warning performance. Even after 20 fire-warning test cycles, the trigger time was 4–8 s when exposed to the fire. Furthermore, in the vertical burning test, the PM 1 A 1 aerogel demonstrated remarkable flame retardancy with a limiting oxygen index (LOI) as high as 53% and quickly self-extinguished. Meanwhile, the peak heat release rate of the PM 1 A 1 aerogel was reduced by more than 65% compared with that of the PI aerogel . In addition, the PM 1 A 1 aerogel also represented a good performance in thermostability and thermal insulation . And the sensitive piezoresistive sensing and controllable Joule heating performance enabled the aerogels to be used in wearable devices and heat management, respectively. After coated with polydimethylsiloxane (PDMS), the obtained PDMS-coated PMA aerogel exhibited superhydrophobic and self-cleaning performance. This work provides a facile approach to fabricate PI aerogel with high fire safety and multi-functions, showing promising applications in transportation, building, firefighting, and wearable devices.
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Journal of Central South University
·
2022
·Vol. 29
·期 6
·1761-1777
·
IF 2.392
Wang Xian-peng,Hu Ai-ping,Chen Xiao-hua,Liu Ji-lei,Li Yan-hua,Li Chuan-yi,Wang Han,Tang Qun-li
The integration of electronic components and the popularity of flexible devices have come up with higher expectations for the heat dissipation capability and comprehensive mechanical performance of thermal management materials. In this work, after the modification of polyimide (PI) fibers through oxidation and amination, the obtained PDA@OPI fibers (polydopamine (PDA)-modified pre-oxidized PI fibers) with abundant amino groups were mixed into graphene oxide (GO) to form uniform GO-PDA@OPI composites. Followed by evaporation, carbonization, graphitization and mechanical compaction, the G-gPDA@OPI films with a stable three-dimensional (3D) long-range interconnected covalent structure were built. In particular, due to the rich covalent bonds between GO layers and PDI@OPI fibers, the enhanced synergistic graphitization promotes an ordered graphitized structure with less interlayer distance between adjacent graphene sheets in composite film. As a result, the optimized G-gPDA@OPI film displays an improved tensile strength of 78.5 MPa, tensile strain of 19.4% and thermal conductivity of 1028 W/(m·K). Simultaneously, it also shows superior flexibility and high resilience. This work provides an easily-controlled and relatively low-cost route for fabricating multifunctional graphene heat dissipation films.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2021
·
IF 5.816
Jun Liu,Haorui Duan,Wenjie Xu,Jun Long,Wenheng Huang,Huan Luo,Jinchao Li,Yaping Zhang
A novel sulfonated multi-wall carbon nanotubes (s-MWCNTs) filler is synthesized by ring-opening reaction. And then, a series of branched sulfonated polyimide (bSPI)/s-MWCNTs composite membranes are also prepared for application in vanadium redox flow batteries (VRFBs). The optimized bSPI/s-MWCNTs-2% composite membrane has lower vanadium ion permeability (2.01 × 10 −7 cm 2 min −1 ) and higher proton selectivity (1.06 × 10 5 S min cm −3 ) compared to those of commercial Nafion 212 membrane. Moreover, the VRFB with bSPI/s-MWCNTs-2% composite membrane exhibits higher coulombic efficiencies ( CE s: 96.0–98.2%) and energy efficiencies ( EE s: 79.7–69.5%) than that with Nafion 212 membrane ( CE s: 86.5–92.5% and EE s: 78.5–67.6%) at 80–160 mA cm −2 . The VRFB with bSPI/s-MWCNTs-2% composite membrane has stable battery performance over 400 cycles at 100 mA cm −2 , whose EE value is in the top level among previously reported SPI-based composite membranes. The results show that the bSPI/s-MWCNTs-2% composite membrane has a great prospect in VRFB application.
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JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
·
2021
·
IF 2.569
Yuejia Li,Wei Pan,Fenghua Zhang,Jinsong Leng
Shape memory polymers (SMPs) are smart materials that can be programmed to change shape under external stimuli, whereas the low storage modulus limit the application of them. Herein, carbon fabric (CF) reinforced shape memory polyimide composites (SMPICs) with high storage modulus were manufactured via hot pressing molding process. Firstly, we synthesized one kind of thermoplastic shape memory polyimide (SMPI) with glass transition temperature of 205°C by the two-step high-temperature solution polycondensation. In addition, the triamine was added in the SMPI system as a crosslinking agent to form the thermosetting SMPI with different crosslinking degree. In order to improve the storage modulus of SMPI, the CFs with three layers were embedded in thermosetting SMPI matrix. The storage modulus of the obtained SMPICs was as high as 26 GPa. The glass transition temperature and thermal decomposition temperature of SMPICs were up to 213°C and 505°C, respectively. Moreover, the shape fixation rate and recovery rate of SMPICs were both more than 94%. These SMPICs with high storage modulus is of great significance, proving more application potential in many fields such as aerospace.
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