ACS Applied Materials & Interfaces
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2022
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IF 10.383
Shuai Zheng,Lei Jiang,Fan Chang,Changqi Zhang,Ning Ma,Xueqiang Liu
High-performance thermal insulating materials are highly desirable in several fields, especially for thermal insulation of buildings to reduce energy consumption. Owing to the remarkable thermal stability, high porosity, low density, and outstanding mechanical features, polyimide (PI) aerogels have attracted great attention. In this work, chemical cross-linked PI (CCPI) aerogels were fabricated via freeze-drying and thermal imidization, which possess outstanding mechanical properties, good thermal stability, and excellent thermal insulation characteristics. The chemically cross-linked structure can effectively inhibit shrinkage, while retaining the structural integrity, resulting in the lower density and lower shrinkage of the materials. In this paper, completely imidized and highly cross-linked polyimide aerogels were synthesized by using p-phenylenediamine (PDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), and the cross-linker 2,3,6,7,14,15-hexaaminotriptycene (HMT). The CCPI aerogels with excellent properties, such as covalently cross-linked chemical structure, low density (0.069 g/cm3), low volume shrinkage (10%), high decomposition temperature (Td5% = 587 °C), and low thermal conductivity (25 mW m–1K–1) are in high demand in the field of thermal insulation. This work furnishes a new method for the development of polymer-based thermal insulation materials for various prospective applications.
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Journal of Central South University
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2022
·Vol. 29
·期 6
·1761-1777
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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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COMPOSITES SCIENCE AND TECHNOLOGY
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2022
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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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Energy & Environmental Materials
·
2022
·Vol. 6
·期 1
·e12427
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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
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2022
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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
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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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Polymers
·
2023
·Vol. 15
·期 10
·2385
·
IF 5
Huimin Qi,Yang Lei,Xuemei Lei,Ding Zhang,Yafeng Zhang,Jiaxin Yu,Baogang Guo
Polyimide-bearing retainer has been successfully used in space environment. However, the structural damage of polyimide induced by space irradiation limits its wide use. In order to further improve the atomic oxygen resistance of polyimide and comprehensively investigate the tribological mechanism of polyimide composites exposed in simulate space environment, 3-amino-polyhedral oligomeric silsesquioxane (NH2-POSS) was incorporated into a polyimide molecular chain and silica (SiO2) nanoparticles were in situ added into polyimide matrix and the combined effect of vacuum environment, and atomic oxygen (AO) on the tribological performance of polyimide was studied using bearing steel as the counterpart by a ball on disk tribometer. XPS analysis demonstrated the formation of protective layer induced by AO. The wear resistance of polyimide after modification was enhanced under AO attack. FIB-TEM confirmed that the inert protective layer of Si was formed on the counterpart during the sliding process. Mechanisms behind this are discussed based on the systematic characterization of worn surfaces of the samples and the tribofilms formed on the counterbody.Keywords:polyimide;NH2-POSS;tribological properties;atomic oxygen;tribofilm
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JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
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2021
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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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Nature Communications
·
2023
·Vol. 14
·期 1
·1-10
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IF 16.6
Xue Tiantian,Zhu Chenyu,Yu Dingyi,Zhang Xu,Lai Feili,Zhang Longsheng,Zhang Chao,Fan Wei,Liu Tianxi
Polyimide aerogel fibers hold promise for intelligent thermal management fabrics, but their scalable production faces challenges due to the sluggish gelation kinetics and the weak backbone strength. Herein, a strategy is developed for fast and scalable fabrication of crosslinked polyimide (CPI) aerogel fibers by wet-spinning and ambient pressure drying via UV-enhanced dynamic gelation strategy. This strategy enables fast sol-gel transition of photosensitive polyimide, resulting in a strongly-crosslinked gel skeleton that effectively maintains the fiber shape and porous nanostructure. Continuous production of CPI aerogel fibers (length of hundreds of meters) with high specific modulus (390.9 kN m kg −1 ) can be achieved within 7 h, more efficiently than previous methods (>48 h). Moreover, the CPI aerogel fabric demonstrates almost the same thermal insulating performance as down, but is about 1/8 the thickness of down. The strategy opens a promisingly wide-space for fast and scalable fabrication of ultrathin fabrics for personal thermal management.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Zhenggang Wang,Jianwei Yuan,Renhao Li,Haipeng Zhu,Jingui Duan,Yanan Guo,Gongping Liu,Wanqin Jin
Compared with traditional separation methods, membrane-based technology shows advantages in energy efficiency for natural gas purification. To overcome the performance trade-off of conventional polymeric membranes, in this study, ZIF-301 MOF was employed as novel filler to fabricate 6FDA-DAM polyimide mixed-matrix membranes (MMMs) for CO 2 /CH 4 separation. A solvent exchange approach was proposed to remove the high-boiling-point solvent used for fabricating the MMMs. The microstructures and physico-chemical properties of the ZIF-301 fillers and ZIF-301/6FDA-DAM MMMs were characterized by SEM, EDX, XRD, IR, TGA, DSC and high-pressure sorption isotherms. The CO 2 /CH 4 transport properties through the MMMs were evaluated by permeation measurement at various feed pressures and analyzed by solution-diffusion model. The results showed that the incorporation of ZIF-301 into 6FDA-DAM enhanced both the CO 2 permeability and CO 2 /CH 4 selectivity, attributing to the preferential CO 2 sorption and aperture molecular sieving effect of the ZIF-301 filler. The MMM with optimal ZIF-301 loading of 20 wt% exhibited CO 2 permeability of 891 barrer and CO 2 /CH 4 of 29.3 that surpassed the 2008 Robeson upper-bound, suggesting that ZIF-301 based membrane could be a potential candidate for natural gas purification.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2021
·Vol. 138
·期 35
·50869
·
IF 3.125
Xiaoqing Xu,Dechao Hu,Wenshi Ma
Achieving synergetic improvements of mechanical strength, toughness, and thermal stability of epoxy resin has been a crucial but very challenging issue. Herein, to explore a new solution for circumventing this issue, polyimide microspheres were successfully prepared through the inverse nonaqueous emulsion process, and the structure, size distribution and morphologies of polyimide (PI) microspheres were comprehensively investigated. Then the PI microspheres were incorporated in epoxy resin matrix to systematically investigate the mechanical and thermal properties of obtained epoxy/PI microspheres composites. It was found that the PI microspheres can not only enhance the mechanical strength of epoxy resin, but also significantly improve the toughness. Specially, the epoxy-based composites containing 3 wt% PI microspheres exhibit a 47% increase in tensile strength, while the G IC and Charpy impact strength increase by 106% and 200%, respectively. The toughing mechanism of epoxy/PI microspheres composites was discussed. Moreover, the PI microspheres can also endow the epoxy resin with excellent thermal stability and heat resistance. Thus, this work may open a new opportunity to synergistically enhance the mechanical and thermal properties of epoxy-based composites and may also give some valuable inspiration for the rational design of other high-performance thermosetting composites.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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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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