查找使用阿拉丁产品的科研文献

Breaking the strength-toughness trade-off in high-performance polyimide nanocomposites using solution-processable aminated heterocyclic polyamide-grafted graphene oxide at ultralow loading

Tao Shen,Yewei Jin,Mao Peng

Despite extensive research on graphene oxide (GO) functionalization with small molecules, oligomers and flexible-chain polymers, grafting rigid-chain polymers onto GO remains largely unexplored. Conventional GO modifications enhance the strength of polyimide (PI) while compromising ductility. Herein, we synthesized a novel aminated heterocyclic aromatic polyamide (NH 2 -HAP) and covalently grafted it onto GO via carbodiimide coupling, achieving a high grafting ratio of ∼ 37 wt%. Incorporating NH 2 -HAP-grafted GO (GO-g-NH 2 -HAP) into PI through in-situ polymerization, doctor-blading, and then thermal imidization yields nanocomposites with excellent strength, toughness, moisture resistance, and dielectric performance. Amino and imidazole groups in GO-g-NH 2 -HAP promote its uniform dispersion and form strong covalent bonds at the interface, facilitating efficient load transfer. At an ultralow loading of 0.40 wt% GO-g-NH 2 -HAP (∼0.25 wt% GO), the nanocomposite achieves remarkable enhancements in tensile strength (254.1 ± 11.7 MPa, +201 %), modulus (1.70 ± 0.05 GPa, +83 %), elongation at break (54.5 ± 2.4 %, +106 %), and tensile toughness (103.2 ± 6.9 MJ/m 3 , +470 %), overcoming the typical strength-toughness conflict in small-molecule-modified GO/PI nanocomposites. The film also demonstrates an 81 % reduction in water vapor transmission rate, an 88 % decrease in water absorption, and a lower dielectric constant (2.5 vs. 3.2 for neat PI). These exceptional properties make the nanocomposites promising for microelectronics and flexible devices.

A Porous Polyimide Composite Separator with an In Situ-Polymerized PDOL Gel Network for Enhanced Dendrite Suppression and Interfacial Stability in Lithium-Metal Batteries

Yaqi Xu,Tongtong Zhang,Sibudjing Kawi,Yinhui Li

High-energy-density lithium-metal batteries (LMBs) demand separators with enhanced thermal stability, electrolyte affinity, and ionic transport capability. Herein, a composite separator composed of polyimide, poly(1,3-dioxolane), and lithium bis(trifluoromethanesulfonyl)imide (PI/PDOL/LiTFSI) is developed by preparing a porous support layer via nonsolvent-induced phase separation followed by in situ polymerization, aiming to overcome the limitations of conventional polyolefin-based separators. Density functional theory calculations confirm that the PI/PDOL system enhances Li+ cooperative coordination through electron-rich sites and lowers the HOMO energy of the gel polymer electrolyte, thereby improving high-voltage oxidation stability. The incorporation of LiTFSI further enhances the ionic transport capability and interfacial stability of the LMBs, enabling the composite separator to achieve an ionic conductivity (σ) of 0.61 mS cm–1 along with a Li+ transference number (tLi+) of 0.64. Moreover, the separator exhibits good electrolyte wettability and maintains dimensional stability without noticeable thermal shrinkage up to 200 °C. Electrochemical evaluations reveal outstanding cycling stability, as Li || LiFePO4 cells maintain 96.8% of their capacity following 150 cycles at 0.5 C. Additionally, Li || Li symmetric cells function steadily for 600 h at 1 mA cm–2 without dendrite-induced failure. These findings emphasize the significant promise of the PI/PDOL/LiTFSI composite separator for the upcoming generation of high-energy-density LMBs.

Electrospun polyimide/cellulose acetate propionate nanofiber membrane-based gel polymer electrolyte with fast lithium-ion transport and high interface stability for lithium metal batteries

Gao Chao,Li Xinping,Song Changyong,Wei Guijuan,Zhao Xixia,Wang Shoujuan,Kong Fangong

Polyimide (PI)-based gel polymer electrolytes (GPEs) have been regarded as a hopeful alternative to liquid electrolytes to build safer lithium metal batteries due to their high thermal stability, chemical resistance, insulation properties, and self-extinguishing abilities. However, limited electrolyte affinity and low mechanical strength hindered their application in quasi-solid lithium metal batteries. In this work, a novel composite GPE matrix consisting of highly thermo-stable PI and eco-friendly cellulose acetate propionate (CAP) nanofibers was successfully fabricated by electrospinning. CAP was introduced for the first time to improve the electrolyte wettability by providing polar functional groups and to offer favorable thermal/mechanical properties via hydrogen bonding with the rigid PI chains. As a result, the obtained PI-CAP composite matrix showed ultra-flexibility, high mechanical strength (7.1 MPa), and excellent thermal stability (over 200 °C). The PI-CAP GPE exhibited high ionic conductivity (2.09 × 10 –3 S cm −1 ) and Li + transference number (0.89). The assembled LiFePO 4 /PI-CAP GPE/Li cell displayed a high capacity retention up to 95% after 300 cycles at 1 C and showed better rate capability than the LiFePO 4 /PI GPE/Li cell. The positive effects of CAP on inhibiting lithium dendrite growth and promoting the generation of stable SEI were also confirmed through SEM results of cycled lithium metals. The results indicate that the PI-CAP GPE has a good potential as a cellulose-based quasi-solid electrolyte for lithium metal batteries.

Ultralight and flexible silver nanoparticle-wrapped “scorpion pectine-like” polyimide hybrid aerogels as sensitive pressor sensors with wide temperature range and consistent conductivity response

Huikang Xu,Weijun Chen,Chengyang Wang,Tingting Jia,Dezhi Wang,Gang Li,Daoxiang Zhao,Baojun Cui,Zhen Fan,Xupeng Fan,Haitao Zhang,Tenghai Gan,Hao Xing,Liwei Zhao,Changwei Liu

The demand for sensitive pressure sensors is increasing due to the rapid development of intelligent electronic equipment in high-tech fields such as aerospace and transportation. However, the high-temperature conditions encountered in aerospace applications pose challenges to the performance of flexible sensing materials used in related equipment. In this context, silver nanoparticles (AgNPs)-wrapped polyimide (PI) hybrid aerogels (PI/AgNPs aerogels) with scorpion pectine-like microstructures (SPM) were fabricated by freeze-drying the precursor solution, followed by a thermal imidization reaction and a dipping process with a AgNPs solution. The SPM grew vertically on the layered structure with a height between 20 and 40 μm. These PI/AgNPs provided sufficient structural strength as a support while providing recovery and contact points. The AgNPs were uniformly dispersed on the SPM (with a thickness of 78–120 nm on PI/AgNPs-1). The SPM-interface secondary response structure was used to realize an electrical response in a broad tension (the PI/AgNPs-2 aerogel has changed from −15.63 kPa under 30 % tensile stress to 69.25 kPa under 70 % compression stress). The hybrid aerogels had excellent sensing performance, including good resistance change (89 %), ultra-high sensitivity (6.9 kPa −1 ), the ability to detect different deformations (compression, tension, and bending), and low fatigue after 3000 load-unload cycles. In addition, these aerogels were able to withstand high temperatures up to 250 °C, and they showed good conductivity response consistency at high and room temperatures. These PI/AgNPs aerogels can be used as sensors in extreme conditions such as in aeroengine peripheral electronics for sensing and detecting external loads.

RETRACTED ARTICLE: Effects of Copper Nanoparticles Located in Different Regions of Polytetrafluoroethylene/Polyimide Blends on the Morphology, Mechanical and Tribological Properties of PTFE Composites

Zhao Yuanliang,Qi Xiaowen,Zhang Wenli,Fan Bingli,Yang Qingxiang

The effects of copper nanoparticles (Cu) located in different regions of polytetrafluoroethylene/polyimide (PTFE/PI) blends on the morphology, thermal, mechanical, and tribological properties of PTFE composites were studied. Region one is PI phases (the corresponding composites is denoted as PPC), region two is PTFE phases and the interface between PTFE and PI (the corresponding composites is denoted as PPC-m). Results indicate that the incorporation of Cu nanoparticles into PI phases improves the dispersibility and homogeneity of PI phases. As a consequence, the crystallinity of PTFE composites is reduced, but compressive strength and modulus of PTFE composites are enhanced by 50.3% and 14.4% respectively. In addition, self-lubricity and wear resistance of PTFE composites are improved by 10.4% and 50.5%. Scanning electron microscopy (SEM) demonstrates that PI phases with Cu nanoparticles hinder the direct contact between PTFE matrix and counterparts. However, Cu nanoparticles located in PTFE matrix and the interface between PTFE and PI deteriorates the dispersibility and homogeneity of PI phases, which lead to the poor mechanical and tribological performance of PTFE composites.

Scalable co-cured polyimide/poly(p-phenylene benzobisoxazole) all-organic composites enabling improved energy storage density, low leakage current and long-term cycling stability

Peiyuan Zuo,Jinpeng Li,Donglin Chen,Lingzhi Nie,Liang Gao,Jingyu Lin,Qixin Zhuang

The all-organic high-temperature polymer dielectrics with promising scale-up potential have witnessed much progress in the energy storage area, etc. However, the electron suppression trap mechanisms behind many all-organic dielectrics are still unclear, especially for high temperature resistant poly(p-phenylene benzobisoxazole) (PBO) polymers. To resolve this tough issue, we herein innovatively prepared PBO-based all-organic thin films containing sulfone-based polyimide (P(DSDA-ODA)) functioning as an electron trap phase using a facile and scalable co-curing method. The great linear dielectric properties of the prepared P(DSDA-ODA)/PBO films hold high dielectric thermal stability over the temperature range from 25 °C to 200 °C. The 60 wt% P(DSDA-ODA) systems yield the lowest leakage current (3.8 × 10−8 A cm−2). The tight structure and reduced leakage current enable an enhanced breakdown strength of 60 wt% P(DSDA-ODA)/PBO (470 kV mm−1), which is 1.7 times that of pure PBO. Meanwhile, it can reach 4.16 J cm−3 of energy density, which is 257% higher than that for pure PBO thin films while concurrently maintaining a long stable charge–discharge cycle (at least 5000 times) and high charge–discharge efficiency at 85.10%. Moreover, P(DSDA-ODA)/PBO still exhibits excellent energy storage performance at high temperature compared to PBO. This innovative strategy is further verified by replacing P(DSDA-ODA) with P(6FDA-ODA), and therefore lays a solid foundation for more investigation on scalable all-organic dielectrics.

Easy Green Construction of a Universal Sensing Platform Based on Crystalline Polyimide Covalent Organic Frameworks with Sensitive Fluorescence Response to Metal Ions and Antibiotics

Ning Zhao,Jing-Min Liu,Fei-Er Yang,Shi-Wen Lv,Jin Wang,Shuo Wang

It is of great significance to establish a simple method for sensitively detecting metal ions and antibiotics for food safety. Herein, two crystalline polyimide covalent organic frameworks (COFs) were constructed via a green method, in which no organic solvents were used. Results suggested that both COF-1 and COF-2 with π-conjugated frameworks emitted strong fluorescence originating from the n−π* transition in N,N-dimethylformamide and the alkaline aqueous solution. More interestingly, both COF-1 and COF-2 showed excellent sensing performance for various metal ions and typical antibiotics. Taking COF-1 as the specific research object, the as-synthesized COF-1 exhibited noticeable turn-off fluorescence behaviors for 10 metal ions and 2 antibiotics. A high linear correlation coefficient, a wide linear range, and a low detection limit were achieved in real samples. The aggregation effect and π–π reaction were the possible fluorescence quenching mechanisms. In short, this work provides insights into the synthesis and application of fluorescent sensors based on COFs in food detection fields.

Experimental and Molecular Simulation Study on the Effect of γ-Aminopropyl Triethoxysilane-Modified Nano Silica on the Mechanical and Dielectric Properties of Polyimide Composites

Xinyue Hu,Hong Ruan,Yuqi Li

The synthesis of polyimides with low dielectric constants, high wear resistance, and excellent mechanical properties is crucial to expanding their applications in aerospace and microelectronics. This study employed γ-aminopropyl triethoxysilane to modify the surface of silica, yielding a modified silica/polyimide nanocomposite (KSPI). Molecular dynamics simulations were conducted to evaluate the performance of the KSPI, incorporating the microstructural morphology and interface interaction energy changes. Results demonstrated that adding 0.5 wt.% APS-modified silica improved interfacial bonding, as well as mechanical and tribological properties. Compared with pure polyimide, the tensile strength of KSPI increased by 35.99%, whereas the dielectric loss and wear rate decreased by 52.4% and 54.03%, respectively. Simulations comparing KSPI and silica/polyimide systems revealed a 24.15% reduction in the solubility parameter similarity coefficient R and a 77.02% decrease in the free volume for KSPI, indicating superior compatibility owing to its reaction with silica hydroxyl groups to form Si  O  Si bonds, reduce hydrophilicity, and inhibit agglomeration. γ-aminopropyl triethoxysilane modification improves silica dispersion, enhancing the thermal resistance, tensile mechanical properties, and dielectric properties of the KSPI. This study established a robust preparation method for high-performance polyimide composites and elucidated how interface compatibility regulates polyimide composite performance employing combined theoretical analysis and experimental validation. Highlights γ-aminopropyl triethoxysilane enhances silica and polyimide compatibility. Interface regulation simultaneously improves polyimide mechanical properties. Molecular simulations revealing correlations between interface and performance. The modified composite exhibits higher thermal stability and lower dielectric loss.

Synergistic effect of thermal crosslinking and thermal rearrangement on free volume and gas separation properties of 6FDA based polyimide membranes studied by positron annihilation

Jingjing Kong,Junjie Liu,Peiyu Jia,Ning Qi,Zhiquan Chen,Shan Xu,Nanwen Li

Two kinds of polyimide membranes 6F-AP and 6F-AP/DA (APAF:DABA=3:2) were synthesized and heated between 300–450 °C to study the effect of thermal treatment on the chain structure and gas transport performance of membranes. Fourier Transform Infrared (FI-IR) and X-ray diffraction (XRD) measurements show that heating causes rearrangement of polyimide into rigid polybenzoxazole which prevents the effective stacking of polymer chains leading to the increase of d-spacing and fractional free volume. Positron annihilation results confirm the increase of both size and number of free volume due to the thermal rearrangement. The addition of DABA monomer into 6F-AP causes crosslinking during heating, which results in tightening of the rigid chain spacing of benzoxazole, thus leading to slight decrease in the size and number of free volume. The increase in fraction free volume induced by thermal rearrangement can significantly improve the gas permeability of 6F-AP series membranes, which increases from 16.2 and 3.9 barrer to 271.4 and 200.3 barrer for H 2 and CO 2 , respectively, after increasing the heating temperature from 300 to 450 °C. But this is accompanied by a decrease in gas selectivity due to the increase in free volume size. Finally, by careful tailoring the free volume structure through thermal rearrangement and crosslinking, the 6F-AP/DA polyimide treated at 400 °C exhibits a H 2 permeability of 196.4 barrer and a H 2 /CH 4 ideal selectivity of 90, which is above the 2008 Robeson upper bound. Our results indicate that by designing the functional groups of the reaction monomer plus appropriate thermal treatment, the microstructure of polyimide membrane can be effectively adjusted for high-performance gas separation.

High enthalpy efficiency lignin-polyimide porous hybrid aerogel composite phase change material with flame retardancy for superior solar-to-thermal energy conversion and storage

Jintao Huang,Jingtao Su,Weihao Xu,Jiahui Lin,Mengman Weng,Yidong Liu,Yonggang Min

Liquid-solid organic phase change materials (PCMs) exist shortcomings of leakage, poor solar-to-thermal conversion efficiency, and flammability , which restrict the application scope of solar-thermal energy storage. To meet these problems, PCMs (ZrP-PI@PEG) with excellent thermal energy storage, solar-to-thermal conversion, and flame retardancy were fabricated in this study. The polyimide (PI)/sodium lignosulfonate-zirconium phosphate (SL-ZrP) hybrid-aerogels (ZrP-PI) were prepared by freeze-drying and thermal imidization. ZrP-PI aerogels composited with polyethylene glycol (PEG) via vacuum impregnation to fabricate the composite PCMs (CPCMs, ZrP-PI@PEG). The in-situ biochar generated from SL-ZrP increases both solar-to-thermal conversion and flame retardant of CPCMs. The final result demonstrates that ZrP-PI@PEG exhibits a superior adsorption ratio (95.5%) and outstanding latent heat (157.67 J/g), as well as about 13% flame retardant index decrease in heat release rate (HRR) and total heat release rate (THR). Furthermore, ZrP-PI@PEG shows great thermal stability and reliability after conducting a leakage experiment and thermal cycling test. These superior resultants indicate that ZrP-PI@PEG has a good potential for widespread and long-term use in solar thermal energy storage.

Nano iron oxide-deposited calcium copper titanate/polyimide hybrid films induced by an external magnetic field: toward a high dielectric constant and suppressed loss

Qing Guo Chi,Jiu Feng Dong,Chang Hai Zhang,Ching Ping Wong,Xuan Wang,Qing Quan Lei

In this paper, we report promising dielectric characteristics of iron oxide-deposited nanosized calcium copper titanate (nano CCTO–Fe3O4)/polyimide (PI) hybrid films induced by an external magnetic field. Nano CCTO particles with a pure perovskite cubic structure and without impurity phases were prepared, and then Fe3O4 nanoparticles were deposited as discrete units on the surface of CCTO to fabricate nano CCTO–Fe3O4 hybrid particles. The effects of magnetic field treatments on the dielectric properties of the composites were investigated in detail. The nano CCTO–Fe3O4/PI hybrid films annealed under an applied magnetic field exhibited a substantial increase in dielectric permittivity, a slight increase in dielectric loss, and a decrease in the percolation threshold. For the hybrid composites subjected to a magnetic field treatment for 30 min at 90 °C, a high dielectric permittivity of 308 and relatively low dielectric loss of 0.60 at 100 Hz were simultaneously achieved when the content of nano CCTO–Fe3O4 was only 12 vol%. Such composites are promising for applications in electronic devices. The experimental results are well explained by percolation theory, which indicated that the enhanced dielectric properties of the hybrid films mainly originated from the large interfacial area and interfacial polarization induced by the external magnetic field.

Synthesis of photosensitive polyimide for liquid crystal alignment under non-polarised UV ageing lamp irradiation and a study on the possible mechanism of alignment

Gang Zhu,Fei Wang,Wenjie Liu,Xinjian Gong,Pengfei Geng,Zhenwei Gao,Yinghan Wang