TRIBOLOGY INTERNATIONAL
·
2024
·
IF 6.1
Baokai Zhang,Xianqiang Pei,Yanming Wang,Shanhong Wan,Gai Zhao,Qihua Wang,Tingmei Wang
Novel organic coatings were developed by incorporating solvent-free covalent carbon quantum dots nanofluids (CQDs NFs) into a polyimide (PI) matrix. The tribological properties of CQDs NFs/PI composite coatings were tested using a ball-on-disk tribometer, revealing that even a low loading of CQDs NFs significantly improved tribological performance of PI. Molecular dynamics (MD) simulations and nanoindentation tests showed that CQDs NFs restricted PI molecular chain movement, enhancing mechanical properties. Additionally, CQDs NFs promoted the formation of stable transfer films on steel surfaces, improving wear resistance. This study confirms CQDs NFs' effectiveness in modifying PI composite coatings' friction and wear properties.
研究领域:
材料科学
·
摩擦学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2024
·
IF 4.4
Yanan Liu,Ming Hao,Xiaodong Hu,Zhijun Chen,Bo Yang,Yanbo Liu,Xiaoxiao Wang,Yen Wei
Interfacial solar steam generation has been regarded as a promising method to produce freshwater from seawater. Nevertheless, achieving simultaneous optimization of high evaporation efficiency along with stability and durability remains a substantial obstacle for polyimide (PI)-based solar evaporators. Herein, a hierarchically structured PI/MXene composite aerogel was prepared by electrostatic spinning, freeze-drying, and thermal imidization. The combination of PI nanofibers and MXene endows the hybrid aerogels with three-dimensional porous structures, intriguing hydrophilicity, and high light absorption, resulting in augmented light-to-heat conversion efficiency. Furthermore, the PI/MXene composite aerogel exhibits an excellent water evaporation rate of 1.459 kg m–2 h–1 under 1 sun with a high photothermal conversion efficiency of 95.6%. The PI/MXene composite aerogel possesses distinct salt resistance, eminent structural stability, and remarkable cycling stability with an evaporation rate of 1.24 kg m–2 h–1 over 10 cycles. This work provides a prospective strategy for constructing highly efficient solar-powered generator with stable performance for practical application in seawater desalination.
研究领域:
材料科学
·
环境工程
·
纳米技术
·
水处理
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2026
·
IF 6
Jiayou Liao,Junling Lin,Shuangming Wang,Zhichao Zhai,Xianjie Meng,Yangyang Wang,Yong Wang,Chengyun Gao,Fanhui Meng,Jinping Li
Mixed matrix carbon molecular sieve membranes are gas separation membranes that combine the synergistic effects of carbon molecular sieves and inorganic components. The DD3R molecular sieve exhibits significant molecular size sieving effects and demonstrates high adsorption selectivity toward CO2. Against the backdrop of the current push for carbon neutrality, highly efficient CO2 separation materials are of great significance to the development of carbon capture and storage (CCS) technology. This is particularly true in natural gas purification and industrial exhaust gas treatment, where higher demands are placed on the efficient separation of CO2 and CH4. Based on this, this study used the DD3R molecular sieve as the functional filler, used 6FDA-DAM polyimide as the precursor, and obtained the hybrid matrix carbon membrane through a high-temperature carbonization process. The microstructure and physicochemical characteristics of the carbon membranes were systematically characterized using scanning electron microscopy and other techniques, and the effect of DD3R loading on their gas separation performance was investigated. The results indicate that as the doping concentration of DD3R molecular sieves increases, both the CO2 permeability and CO2/CH4 separation selectivity of the mixed matrix carbon molecular sieve membranes exhibit a trend of initially increasing and then decreasing. Furthermore, when the DD3R doping mass fraction reached 0.3 wt %, the prepared carbon membrane exhibited optimal performance, achieving a CO2 permeability coefficient of 29,679 Barrer and a CO2/CH4 selectivity of 33.1, surpassing the Robeson upper limit reported in 2019. The results indicate that, owing to the unique pore structure of the DD3R molecular sieve and its synergistic interaction with the carbon matrix, the carbon membrane effectively overcomes the trade-off between permeability and selectivity, demonstrating significant potential for industrial applications and holding broad prospects in the field of carbon capture.
✓ 已验证
DOI
高影响因子
Fire-Switzerland
·
2026
·Vol. 9
·期 2
·81
·
IF 3.2
Zhi Li,Fang Zhou,Kai Shen,Miao Liu,Yumin Duan,Jiahui Chen,Shuai Li,Haoxuan Yu
Polyimide aerogels (PIAs) possess enormous application potential in high-temperature thermal insulation scenarios. As high-efficiency thermal insulation materials, their thermal safety and thermal insulation performance are of crucial importance. Currently, poor dimensional stability, high-temperature pyrolysis, and severe shrinkage remain the key factors restricting their development and practical application. In this work, we employ an in situ co-gelation synthesis strategy, where methyltrimethoxysilane (MTMS) is introduced as the silica precursor to fabricate SiO2/polyimide aerogels (Si@PIAs). This strategy enhances the interfacial bonding strength between the organic and inorganic phases, enabling their complementation of strengths. Experimental results demonstrate that the incorporation of the inorganic SiO2phase endows Si@PIAs with higher thermal safety, superior thermal insulation performance, lower density, and reduced shrinkage. Among them, Si10@PIA performs best with a density of 85 mg/cm3, a thermal conductivity of 23.28 mW/(m·K), and a heat flow peak temperature of 720.7 °C. More importantly, pyrolysis analysis reveals that the pyrolysis process of Si@PIAs shifts to a randomized nucleation and growth model (n= 2/5) with the mechanism functiong(α) = [−ln(1 −α)]5/2. Compared with pure PIAs, Si@PIAs possess stronger resistance to pyrolysis, lower gross calorific value, and improved thermal safety. This study provides theoretical and practical guidance for the development of high-performance aerogel materials, promoting their application in lithium-ion battery separators, high-temperature insulation, and fire-resistant materials.
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Storage
·
2026
·
IF 10.7
Zhichao Pang,LiZhu Guan,Tianyu Hu,Ling Weng,Yi Jin,Yao Wu,Dongbo Xi,Dongming Shi
With the development of modern power electronic systems, there is an urgent demand for polymer dielectric materials that can operate efficiently for a long time under high temperature and high electric field. In this study, a polyimide (PI)-derivative containing spirocyclic groups was designed. The spirocyclic groups possess a rigid three-dimensional structure, which can effectively destroy the conjugated plane of PI polymer to block intramolecular charge transfer. Meanwhile, the large steric hindrance of the spirocyclic groups increases the distance between molecular chains and disrupts π-π stacking, thus hindering intermolecular charge transport. These effects jointly widen the bandgap and reduce the carrier mobility of the PI derivative. The composite film obtained by blending this PI-derivative with conventional PI exhibits the maximum discharge energy density of 4.78 J/cm 3 with the charge-discharge efficiency of 87.5% under 550 MV/m at 150 °C, outperforming most high-temperature polymer dielectrics. This work provides a feasible strategy for the design of polymer dielectrics targeted at high-temperature energy storage applications.
✓ 已验证
DOI
高影响因子
ACS Omega
·
2026
·
IF 5.2
Jiaozhu Wu,Jiaxi Zhang,Xutao Zhang,Haoyu Ma,Jie He,Qiang Liu,Guangxian Li,Pengjian Gong
Abstract The microwave absorption performance depends on both impedance matching and electromagnetic energy dissipation. Conventional filler-functionalized polyimide (PI) composites can provide strong electromagnetic attenuation, but their limited foamability under supercritical carbon dioxide (scCO2) restricts porous structure formation and thus impairs impedance matching. To address these limitations, this study proposes an intrinsic molecular modification strategy based on a chain segment design. Furthermore, by combining synergistic dielectric-magnetic loss from nanofillers with a double-layer heterogeneous architecture, a PI-based electromagnetic shielding nanocomposite with strong microwave absorption performance and low-reflection characteristics was constructed. Bisphenol A dianhydride (BPADA) was used as the dianhydride monomer, and a series of PI copolymers with tunable chain segment compositions were prepared through the reaction of BPADA with mixed aromatic diisocyanate (MDI) and aliphatic diisocyanate (HDI), followed by thermal imidization/cyclization. The changes in molecular chain mobility, scCO2 foaming behavior, and cellular structure associated with the nominal HDI feed fraction were systematically investigated. The results showed that increasing the nominal HDI feed fraction was associated with an improved rigid-flexible balance of the PI backbone, enhanced segmental mobility, a broader foaming window, and the formation of PI foams with uniform and compact cellular structures. CNT@Fe3O4 nanofillers with both dielectric and magnetic loss capabilities were further introduced to improve the intrinsic electromagnetic loss of the composite foams. The calculated microwave absorption results showed that, after pore structure regulation, the PI/CNT@Fe3O4 nanocomposite foam exhibited markedly enhanced microwave absorption in the X-band. At a porosity of 46 vol %, the minimum reflection loss reached −38 dB at a thickness of 2 mm. A double-layer heterogeneous structure comprising a CNT@Fe3O4-containing porous absorbing layer and a CNT-containing dense reflecting layer was then constructed to exploit impedance gradient transition, dielectric-magnetic synergistic loss, and multiple reflection/reabsorption processes. The optimized sample showed an average absorption coefficient of 0.92 in the X-band and a maximum A/R ratio of 332, indicating pronounced high absorption and low reflection characteristics. This study provides a new strategy for designing and fabricating lightweight, high-performance PI-based electromagnetic protection materials with an absorption-dominated shielding behavior.
✓ 已验证
DOI
高影响因子
ACS Applied Polymer Materials
·
2025
·
IF 4.7
Yiwei Wang,Guan Wang,Li Zhang,Bilal Iqbal Ayubi,Guowei Hou
Polyimide (PI) is widely used as the primary dielectric in solid-state transformers (SSTs), yet rapid degradation under kilohertz, kilovolt pulses at elevated temperature remains insufficiently understood. In practical geometries with gas gaps and exposed edges, partial discharges (PD) localize field at triple points, leading to extrinsic failure. By integrating in situ diagnostics (30 kHz partial discharge monitoring, FTIR, SEM/EDS, and PEA space charge mapping) with a three-tier simulation chain (ReaxFF-MD → TD-DFT → electrothermal phase-field), this work provides an integrated bond-to-breakdown view of PI aging under high-frequency electrical stress. Experiments reveal a nonmonotonic evolution of partial discharge (PD) activity: the PD pulse amplitude and repetition rate first rise and then fall as aging progresses. Reactive molecular dynamics pinpoints C–N/C–C scission in the imide ring, whose CO off-gassing and defect formation halve the PI’s HOMO–LUMO gap (from 5.32 to 2.57 eV). Time-dependent DFT confirms a markedly lower excitation threshold and stronger hole–electron overlap in the defected structure, explaining the trap-assisted charge retention observed by PEA. Using frequency- and temperature-dependent dielectric parameters, a phase-field model incorporates dielectric-loss heating and successfully reproduces the experimentally observed transition from sparse electrical treeing to a continuous breakdown channel with localized thermal runaway. Finally, a physics-informed lifetime model is formulated and fitted to accelerated aging data, quantifying how high-frequency PD damage and dielectric-loss heating together expedite insulation failure. The results establish a defect-mediated, PD-initiated extrinsic electrothermal aging mechanism in PI under kHz excitation and demonstrate a predictive framework for lifetime estimation, thereby guiding the design of polymer dielectrics for high-frequency power equipment.
✓ 已验证
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2026
·
IF 5.8
Anis Alam,Tingkai Zhao,Syeda Khair Un Nisa
Flexible solid-state supercapacitor electrodes require fiber-shaped conductors that combine high electrical conductivity and textile-level mechanical compliance. However, transforming engineering polyimide (PI) fibers from electrically insulating structural supports into integrated conductive electrodes without sacrificing their intrinsic mechanical integrity remains a significant challenge. In contrast to previously reported MXene/CNT/polymer-based flexible fibers, which are predominantly built on soft or elastomeric matrices, achieving high conductivity within a high-temperature structural polyimide while preserving its strength and toughness remains largely unexplored. Herein, we converted intrinsically insulating PMDA–ODA polyimide (PI) into conductive and mechanically robust fibers by wet-spinning of Ti 3 C 2 T x MXene- and carbon nanotube (CNT)-loaded polyamic-acid (PAA) dopes followed by thermal imidization. The resulting MXene (2D)–CNT (1D)–PI fibers exhibit a hierarchical 1D–2D conductive network in which CNTs bridge MXene sheets, suppress restacking, and reduce interflake resistance. The experimental results show that the electrical conductivity increases from ∼1.6 × 10 –10 S·m -1 for pristine PI to 1.61 S·m -1 for MXene/PI and further to 1.5 × 10 2 S·m -1 for MXene–CNT–PI. Using a solid H 3 PO 4 /PVA gel as the electrolyte, the optimized multicomponent fibers display nearly rectangular cyclic voltammetry curves, quasi-triangular charge–discharge behavior, volumetric capacitances of 80–20 F·cm -3 at 0.05–0.20 A·cm -3 , and ∼68% capacitance retention after 5000 cycles. Importantly, despite the incorporation of conductive nanofillers, the fibers retain high tensile strength (∼200 MPa), large elongation (∼35–40%), and high toughness (∼30–32 MJ·m -3 ), approaching that of pristine PI. This work demonstrates a scalable strategy to convert structural polyimide fibers into conductive, mechanically robust electrodes suitable for flexible solid-state energy-storage systems.
✓ 已验证
产品关联
DOI
高影响因子
SURFACE AND INTERFACE ANALYSIS
·
2026
·
IF 2.7
Xu Zhaohong,Li Jian,Tang Xiaodong
Pentaerythritol phosphate (PEPA) grafted TiO 2 and CNT were coated layer by layer onto the surface of carbon fibers to reinforce polyimide (PI) composites. The effect of PEPA grafted TiO 2 and CNT on the mechanical properties of CF/PI composites was studied by scanning electron microscope, contact angle measurement and X-ray photoelectron spectroscopy. The results show that PEPA grafted TiO 2 and CNT can significantly increase the surface activity and specific surface area of carbon fiber, and improve the wettability, reactivity and mechanical meshing between resin and carbon fiber. The interfacial properties and mechanical strength of the composites are improved. The interlaminar shear strength (ILSS) and flexural strength of PEPA grafted TiO 2 /CNT composite grafted carbon fiber composites were increased by 96.2% and 89.7%, respectively.
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2026
·
IF 5.2
Ziteng Guo,Bo Zhao,Ziyi Wang,Kang Xie,Weicheng Zhang,Zhihua Li
Developing high-temperature polyimide (PI) adhesives requires the simultaneous enhancement of bulk cohesive strength and interfacial adhesion. In this work, a 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA)/4,4′-oxidianiline (ODA)-based phenylethynyl-terminated PI system was modified via a 30k/8k molecular weight blend strategy to prepare processable, self-supporting adhesive films. To enhance performance, three distinct polar diamines (sulfone, amide, cyano) were introduced to replace a portion of the ODA. This strategy aimed to strengthen substrate wetting for improved interfacial adhesion and to reinforce bulk cohesion through hydrogen bonding. It is confirmed that the amide-containing sample (PI-A50) was the most effective, showing the highest polarity with a dielectric constant of 3.9 and the highest total surface energy of 51.87 mJ/m2. It has also maintained excellent thermal stability, with a glass transition temperature (Tg) of 317 °C and a temperature at 5% weight loss (Td5%) of 537 °C. Molecular dynamics (MD) simulations revealed the unique synergistic mechanism for its superior performance. The –CONH– group not only showed a stronger interfacial binding energy with the Al (111) substrate, calculated at −19048.7 kcal/mol, but also formed the densest interchain hydrogen bond network, which explains why it achieved the highest cohesive energy density of 200.42 J/cm3 and the lowest fractional free volume of 44.28%. This simultaneous strengthening of both bulk cohesion and interfacial adhesion is the key to its enhanced performance.
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2026
·
IF 5.1
Qingnan Wang,Yueyangchao Yu,Longjie Liu,Yi Ye,Xinglei Zhao,Chongshan Yin,Bin Liu,Shaofei Wang
Efficient separation of CO 2 from CH 4 is a critical unit operation for biogas upgrading and achieving carbon neutrality goals. While mixed-matrix membranes (MMMs) offer an energy-efficient alternative to traditional separation processes, their industrial deployment is often restricted by engineering challenges, specifically filler agglomeration and non-selective interfacial defects. Herein, we report a novel MOF (metal–organic framework) gel network templated polymerization strategy that effectively circumvents these limitations. In this approach, a continuous, pre-formed network of UiO-66 MOF gel serves as a structural scaffold, within which the 6FDA-ODA polyimide matrix is directly polymerized. This method fosters exceptional interfacial adhesion and uniform dispersion of the filler, successfully eliminating non-selective defects. The resulting MMMs exhibit remarkable gas separation performance, with the optimal membrane (MA-0.075, with 1.6 wt% UiO-66 gel loading) achieving a CO 2 permeability of 30.9 Barrer and a CO 2 /CH 4 selectivity of 135.5 under mixed-gas conditions. This represents enhancements of 212 % and 162 %, respectively, over the pristine 6FDA-ODA polyimide membrane, surpassing the 2008 Robeson upper bound. Furthermore, the membrane demonstrated excellent operational stability over 120 h. This work provides a scalable fabrication route for advanced MMMs, demonstrating significant potential for energy-efficient gas separation applications.
✓ 已验证
产品关联
DOI
高影响因子
CARBON
·
2026
·
IF 12.7
Wei Chu,Yong Fang,Xiao Sun,Yujie Zhang,Yachuan Miao,Qiangli Zhao,Qiye Wen,Jianwei Li
With the increasing severity of electromagnetic (EM) pollution, conductive porous materials have been widely used as effective electromagnetic interference (EMI) shielding materials to protect electronic equipment and human health. Although conventional conductive porous materials exhibit better impedance matching and lower EM wave reflection than metal-plate-based shielding materials. It remains challenging to overcome their poor mechanical strength and large thickness. In this study, we fabricated hot-pressed hierarchically porous polyimide foam (PF)/carbon black (CB)/Ni–P and PF/CB/Fe 3 O 4 –P composites with continuous conductive pathways using a chemical foaming and hot-pressing strategy. Benefiting from the continuous conductive pathways and hierarchically porous architecture, PF/CB/Ni–P containing 80 wt% Ni nanoparticles achieved a maximum EMI shielding effectiveness (EMI SE) of 60.7 dB in the X-band at a thickness of 5 mm. Meanwhile, the thicknesses of PF/CB/Fe 3 O 4 –P and PF/CB/Ni–P were further reduced by the hot-pressing strategy, exhibiting optimal absorption coefficients (A) of 0.51 and 0.68, respectively. The results demonstrate that this preparation method achieves excellent comprehensive performance, including enhanced mechanical strength and absorption-dominated EMI shielding, providing a promising approach for designing adaptive EMI shielding systems for aerospace and electronic applications. Download: Download high-res image (349KB) Download: Download full-size image
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）