查找使用阿拉丁产品的科研文献

Preparation and alignment properties of photosensitive polyimide containing benzophenone in main chain

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

Lightweight 3D-net Copper-Plated Polyimide Current Collector for Lithium-Ion Batteries

Tingyu Song,Yonggang Min

Graphical In this work, 3D-net copper-plated polyimide current collector was prepared through electroless plating method and obtained a structure of PI core and Cu shell. This novel current collector possesses a lightweight areal density. Three different Cu loading copper-coated PI CC samples was prepared and compared. The lithium-ion batteries assembled with Cu-PI CC 2 exhibit better performance. Current collector (CC) is an indispensable constituent in lithium-ion battery (LIB). It plays an important role in supporting electrode materials and conducting electrons between the electrode materials and the external circuit. However, the density of metal CC is high and it hinders the lightweight development of LIB. In this work, lightweight three-dimensional (3D) CC was designed and prepared via a facile electroless plating method. The 3D copper-plated polyimide CC has a low areal density. The 3D structure of Cu-PI CC 2 can facilitate Li + transfer between electrode materials and electrolyte owing to electrolyte can permeate through electrode. Moreover, the lithium titanate anode assembled with the 3D copper-plated polyimide Cu-PI CC 2 exhibited enhanced cycling and rate performance.

Enhancing the dielectric properties of polyimide-based composites with donor-doped SiO2

Wenchao Zhang,Liangjun Wang,Shiyu Liu,Feng Guan,Min Jiang,Yanpeng Li,Dong Yue,Jialong Li,Xiaoxu Liu,Yu Feng

It is important that the dielectric material in the electrical system be able to handle the increasing applied electric strength owing to the rising demands for power supply reliability. Based on this, in this work, Nb 2 O 5 donor doped SiO 2 (NSO) particles were synthesized by high-temperature sintering method and successfully doped into the PI matrix. The maximum E b of the composite material is 527.3 kV/mm, which is 64.2% higher than that of pure PI (321.1 kV/mm) and 34.8% higher than that of the SiO 2 /PI composite material (392.5 kV/mm) owning to the effect of donor doping on the carrier transport of the composite material. At the same time, it maintains excellent dielectric stability and lower dielectric loss even at 100 ℃. These consequences offer a new strategy for enhancing the integrated dielectric properties of polymer dielectrics in insulation fields.

Study on Chemical Graft Structure Modification and Mechanical Properties of Photocured Polyimide

Zhiqiang Liu,Yilun Cai,Feifan Song,Jiajin Li,Jian Zhang,Yi Sun,Guoqiang Luo,Qiang Shen

The great challenge facing additive manufacturing is that the available high-performance 3D printing materials can hardly keep up with the rapid development of new additive manufacturing technology. Then, the commercial resins available in the market have some problems, such as poor thermal stability, insufficient light-curing degree, and large shrinkage after curing, which need to be solved urgently. This study reports a photocurable polyimide ink for digital light processing (DLP) 3D printing to prepare controllable 3D structures with high thermal stability, low shrinkage, and excellent comprehensive properties. In this study, pyromellitic dianhydride and diaminodiphenyl ether, the Kapton polyimide with the highest performance synthesized so far, were selected as raw materials, and 2,2′-bis(3,4-dicarboxylic acid) hexafluoropropane dianhydride containing fluorine was introduced to modify the branched-chain structure. The polyimide was prepared by one-step imidization, and then the graft with photocurable double bonds and certain functions was grafted by reaction of glycidyl methacrylate with phenolic hydroxyl groups. In this work, the solubility of the synthesized oligomer polyimide in organic solvents was greatly increased by combining three methods, thereby allowing the formation of ink for photocuring 3D printing, and the ink can be stacked to form low-shrinkage polyimide with complex controllable shape. Polyimide printed by DLP can produce complex structures with good mechanical character and thermal stability and small shrinkage. Therefore, the polyimide prepared in this study is considered to be a resin of great commercial possibility. In addition, due to its properties, it has important development potential in some fields with high demand for thermal stability, such as high-temperature cooling valves, aerospace, and other fields.

Thermal, mechanical investigation and neutron shielding analysis for Gd-MOF/polyimide materials

Chen Hu,Qunying Huang,Yutao Zhai

None of the currently commercialized shielding materials in Generation IV nuclear energy systems are satisfactory in their performance. Developing a candidate neutron shielding material with good heat resistance and high strength is a challenging task. In this work, various gadolinium metal–organic frameworks (Gd-MOFs) with obvious advantages, such as porous structures, organic surfaces and strong neutron-absorbing nuclei, were synthesized to constrain polyimide (PI) chains. A series of Gd-MOF/PI conjugates were subsequently assessed for their thermal stability, mechanical properties and neutron shielding performance. The increase of the Gd-MOF content improved the thermal neutron shielding ability but slightly reduced the fast neutron shielding ability. Compared with those of pure PI, the Gd-MOF/PI films demonstrate a higher glass transition temperature (Tg), which is considered the gold standard of engineering plastics. It was also observed that the tensile strength directly correlates with the Gd-MOF content, which continuously increases until a maximum is reached, and then subsequently decreases. Furthermore, the high-temperature tensile test showed that these tunable Gd-MOF/PI films are intact and robust, indicating their potential application for neutron shielding materials in Generation IV nuclear energy systems.

Anisotropic Polyimide/Cellulose Nanofibril Composite Aerogels for Thermal Insulation and Flame Retardancy

Ruina Zheng,Jiayu Hu,Zhichao Lin,Guozhang Wu,Yu Lin

In this study, we report a series of lightweight, anisotropic polyimide/cellulose nanofibril (PI/CNF) composite aerogels with outstanding thermal insulation and flame retardancy via unidirectional drying and freeze drying methods. Along the axial direction, PI/CNF composite aerogels exhibit an arranged tube-like structure in parallel to ice crystal growth, thus providing superior mechanical properties. Conversely, the composite aerogels show a honeycomb-like pore structure along the radial direction, exhibiting excellent elastic properties. More importantly, the addition of CNF endows the composite aerogels with low thermal conductivity along the radial direction. The surface temperature of the composite aerogels with a thickness of 15 mm is 70% lower than that of hot stage annealing at 180 °C for 60 min. Furthermore, the composite aerogels show flame retardant and self-extinguishing performance in the combustion experiment. Therefore, the anisotropic PI/CNF composite aerogels with thermal insulation and flame retardancy are promising for expanding potential applications in aerospace fields.

A superhydrophobic fluorinated-silica/polyimide nanofiber membrane with ultra-low dielectric constant

Xu Chengze,Wang Xiang,Yu Zhiyong,Gu Jianbo,Feng Xiangyang,Zhang Siyuan

For ultra-large-scale integrated circuits to proceed at a rapid pace, dielectric materials with an ultralow permittivity, excellent mechanical properties, and moisture resistance are highly sought after. Herein, a series of F-SiO 2 /PI nanofiber films with an ultralow- k value have been successfully created by coaxial electrospinning and in situ sol–gel techniques, allowing them to be used under moisture conditions. Thanks to the introduction of fluorinated substituents and high porosity, F-SiO 2 /PI films exhibited ultralow dielectric constants, less than 1.8 at 1 MHz, and high hydrophobicity with contact angles greater than 145°. In addition, when TEOS was added in quantities ranging from 0.25 to 1.00 ml, F-SiO 2 /PI films with dielectric constants of 1.81–2.65 (1 MHz) at 80% R.H., and the water contact angles of 146.1°, 148.0°, 151.9°, and 154.2°, respectively, were obtained, compared to 4.17 of dielectric constant at 80% R.H. and contact angle with water 112.0° for pure PI nanofiber films. In this regard, the F-SiO 2 /PI films offered great promise as an insulating material for electronics and microelectronics.

4,4′,4′′-Triaminotriphenylamine-based porous polyimide as a visible-light-driven photocatalyst

Qin Wang,Jianling Zhang,Yuyan Yu,Yi Dan,Long Jiang

Aiming to develop a visible-light-driven polymeric photocatalyst that can be fabricated by an easy-to-scale-up polymerization method, a porous polyimide (PPI) with a specific surface area (SBET) of 79.3 m2 g−1 was synthesized by a facile polycondensation of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) with 4,4′,4′′-triaminotriphenylamine (TPA). UV-vis diffused reflection spectroscopy (DRS), electrochemical analysis, valence band X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculation results reveal that the prepared PPI possesses a narrow band gap (2.04 eV) with the valence band (VB) located at 1.26 V (vs. NHE) and the conduction band (CB) edge at −0.78 V (vs. NHE), clearly indicating the visible light activity of PPI. The photocatalytic performance for the degradation of methylene blue (MB) in water was studied, and the results demonstrate that PPI possesses excellent photocatalytic activity under visible light irradiation. Electron paramagnetic resonance (EPR) and photo-current analyses were used to study the photocatalytic mechanism, which show that PPI has a lot of single electron trapped oxygen and more light-generated electrons. This work may provide a cost-effective, potentially scalable strategy to design and develop a polymeric photocatalyst with continuously tunable photoelectrical properties.

Facile fabrication of superhydrophobic polyimide/polytetrafluoroethylene composite coatings with high water adhesion

Yonggang Guo,Zhongying Wang,Haihong Wu,Xia Zhang

A facile casting method was used to fabricate superhydrophobic polyimide/polytetrafluoroethylene composite coatings with high water adhesion. The water contact angles of the composite coatings were larger than 150 °, expressing superhydrophobic property. But water droplets pinned tightly on the composite coating, even if it was upside down. The X-ray photoelectron spectrum analysis indicated that polyimide and polytetrafluoroethylene coexisted in the resulting coating. The observation with scanning electron microscopy showed that the composite coating formed lotus-like structure with many spherical polyimide papillae randomly bonding on the surface. But the tops of the polyimide papillae were not covered by lance-shaped Teflon fibres, forming an inhomogenous and discontinuous surface structure. This special surface chemical distribution and lotus-like structure combined to contribute to the high adhesive superhydrophobicity. This simple method may greatly extend the application range of high adhesive superhydrophobic surfaces in microcontrollable and microfluidic application. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42810.

Facile preparation of polyimide/graphene nanocomposites via an in situ polymerization approach

Songlv Qin,Cheng Chen,Mingjun Cui,Afang Zhang,Haichao Zhao,Liping Wang

In this study, to achieve a compatible and good dispersion of graphene in polyimide matrix, we synthesized an aromatic diamine, aniline trimer, as a polymerizable graphene dispersant. Polyimide/graphene nanocomposites with 0.25–2% mass fraction of graphene were prepared by in situ condensation of pyromellitic dianhydride, 4,4′-oxydianiline, and aniline trimer (AT) functionalized graphene in DMAc, following subsequent thermal imidization at elevated temperatures. UV-vis and Raman spectroscopy verified the π–π interactions between AT and graphene. The microstructure analysis using XRD, SEM, and TEM were performed to investigate the morphology of graphene in the polyimide matrix. The thermal, mechanical, and tribological properties of polyimide/graphene nanocomposites were investigated by TGA, DMA, and friction and wear tests. In view of the ease of preparation and their superior physical properties over neat polyimide, PI/G composites prepared in this study showed promising applications as wear-resistant and self-lubricating materials.

Synthesis of novel graphene oxide-polyimide hollow fiber membranes for seawater desalination

Aisheng Huang,Bo Feng

Hollow fiber membranes are more favorable for the fabrication of membrane modules in industry because of its high membrane area to module volume ratios. In the present work, we reported the preparation of novel graphene oxide (GO)/polyimide (PI) hollow fiber membranes for the first time by direct spinning of a GO/PI suspension via a coaxial two-capillary spinning strategy. The structure and morphology of GO/PI hollow fiber membrane was characterized by using XRD , FT-IR and FESEM . The GO nanosheets can homogeneously be dispersed in the PI matrix to form continuous and robust membranes due to a good compatibility between GO and PI, and GO/PI hollow fiber membrane shows a typical asymmetric structure. The performances of the GO/PI hollow fiber membrane were evaluated for desalination of seawater by pervaporation . The GO/PI hollow fiber membrane displays excellent water permeability and salt rejection for desalination of different concentrations of seawater. At 90   °C, a high water flux (15.6   kg   m −2   h −1 ) and a high salt rejection (99.8%) can be obtained. Further, the GO/PI hollow fiber membrane displays a high stability for seawater desalination with a long time measurement.

Preparation and properties of sulfonated polybenzimidazole-polyimide block copolymers as electrolyte membranes

Pan Haiyan,Chen Shixiong,Jin Ming,Chang Zhihong,Pu Hongting

Sulfonated polybenzimidazole-polyimide block copolymers are synthesized through condensation polymerization at high temperature. The length of the polyimide chain is varied to give a series of block copolymers with various block lengths. The as-synthesized block polymers are used to prepare the corresponding membranes through the solvent evaporation method. The structure of the block copolymers is characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Their mechanical strength, thermal behavior, water uptake, swelling ratio, and proton conductivity, as well as oxidative stability are also investigated. All the block copolymers exhibit good thermal stability, dimensional stability, mechanical strength, and proton conductivity. Compared to the random sulfonated polyimide-containing benzimidazole membranes with the same degree of sulfonation, the membranes prepared from the block copolymers show higher proton conductivities. The proton conductivities of the block copolymer membranes range from 6.2 × 10 −4 to 1.1 × 10 −2  S cm −1 at 105 °C. The block copolymer membrane doped with phosphoric acid exhibits proton conductivity higher than 0.2 S cm −1 at 160 °C, indicating its potential applications in proton exchange membrane fuel cells operated under high temperature and low humidity conditions.