POLYMER
·
2022
·
IF 4.432
Ling-jie Zhang,Jian Liu,Long-bo Luo,Xiang-yang Liu,Xu Wang
The combination of high breakdown strength and low dielectric loss has always been a challenge for the preparation of high energy storage density dielectric films . In this work, in order to optimize their dielectric performances, we develop a series of all-organic PI composite films by introducing perchlorinated hexa-peri-hexabenzocoronene (Cl-HBC) molecules with a concentration (0.01–0.1mol%) into PI film. Even at an ultra-low concentration, the Cl-HBC molecule with a quasi-two-dimensional structure would successfully induce the in-plane orientation of PI macromolecular chains and reduce their orientation confusion and molecular cavity. Thus, the existence of Cl-HBC obviously limits the chain mobility of PI in PI-Cl-HBC film under the electric field, which is supposed to reduce the dielectric loss of resulted films. Moreover, Cl-HBC molecules are equipped with a low Lowest Unoccupied Molecular Orbital (LUMO) of about −3.52eV and could work as an electron trap and block the conduction of electrons in the PI composite film. Here, the breakdown strength of the composite film was improved from 442 kV/mm (pure PI) to 539 kV/mm and the dielectric loss was reduced to 0.002. To our best knowledge, it is the first time to significantly enhance the dielectric strength and largely reduce its dielectric loss simultaneously by preparing PI composite film. Meanwhile, compared with pure PI, the energy storage density of composite film increases by 43% and 96% at room temperature and 150 °C, respectively.
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高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Ke Zhao,Siyu Wei,Meng Wang,Yingbo Chen
Owing to the rapid development of the latest micro-electronic devices, polymer composite materials that combine high thermal conductivity and low permittivity have aroused the interest of researchers. However, it is a huge challenge to balance the above parameters. In this work, hexagonal boron nitride (h-BN) powder was ultrasonically exfoliated to obtain alkylated boron nitride nanosheets (Alkyl-BNNS). Then, a series of polyimide (PI) composites were synthesized with different amounts of Alkyl-BNNS. Attributed to more robust interfacial non-covalent interactions between Alkyl-BNNS and polymer chains to inhibit interfacial polarization, Alkyl-BNNS can be scattered well in PI substrate. Thus, the obtained PI composite behaved a high thermal conductivity of 6.21 W/(mK) and a low dielectric constant (3.23) under the load of 20 wt%. Besides, Alkyl-BNNS/PI composites have efficient thermal management capability, low water absorption, favorable electrical resistance, and prominent tensile strength . Importantly, these composite films are expected to be excellent candidates in the field of microelectronics.
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高影响因子
EUROPEAN POLYMER JOURNAL
·
2023
·
IF 6
Hong Li,Feng Bao,Xiaoqian Lan,Shuanger Li,Haoran Zhu,Yadong Li,Mingliang Wang,Caizhen Zhu,Jian Xu
With the rapid development of 5G communications, the traditional interlayer dielectric material polyimide (PI) requires modification due to its intrinsically high dielectric constant (D k ), high dielectric loss (D f ), and high moisture absorption, which make it difficult to meet the needs of the high-frequency communications industry. In this paper, a new strategy for the preparation of novel PI with intrinsically low D k and D f is proposed from the perspective of molecular structure design, the modification effect of superimposing bulky triphenyl pyridine structures and strong electronegativity groups, combined with long-chain anhydride to reduce the density of the imide structure. Therefore, three bulk diamine monomers (BPAB, PBAB3F, PBAB6F) containing triphenyl pyridine structures were designed in this paper and polymerized with 4,4′-(4,4′-isopropyldiphenoxy) phthalic anhydride (BPADA) to obtain three new PIs (PI-H, PI-CF 3 , PI-2CF 3 ) with different fluorine contents, focusing on the relationship between structure and properties, especially the effect of fluorine content on dielectric properties . The results of the study show that the dielectric and hygroscopic properties of PI improve with increasing fluorine content. Among them, PI-2CF 3 has the best overall performance, showing low dielectric (D k = 2.72@10 GHz & D f = 0.00233@10 GHz), high transparency (Cut-off wavelength (λ 0 ) = 389 nm, Maximum transmittance (T via ) = 89%) and low hygroscopicity (Water absorption (M a ) = 0.246%, Contact angle (C a ) = 111°).
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Tongxin Liu,Ruili Zhang,Guangcan Huang,Yabo Xie,Lin-Hua Xie,Jian-Rong Li
Emerging as a new type of porous materials, metal-organic cages (MOCs) show great potential in adsorption and separation. The high porosity and solubility of MOCs have generated increasing interest in their use as fillers for preparing mixed matrix membranes (MMMs). Herein, we present a series of zirconocene-based MOCs (MOC-1, MOC-1-NH 2 , and MOC-1-4F), which were used to fabricate MMMs with polyimide 6FDA-DAM. Particularly, the perfluorinated MOC (MOC-1-4F) could form a clear casting solution with 6FDA-DAM in some solvents. The resultant MMMs were analyzed by AFM, SEM, EDX-mapping, XRD, CSM, Raman, TG, and DSC measurements, indicating that MOC-1-4F were homogeneously dispersed in 6FDA-DAM, and the T g values, mechanical property, CO 2 solubility and diffusivity of the membrane were promoted after the introduction of MOC-1-4F. The MOC-1-4F based membranes also outperformed the membranes with MOC-1 or MOC-1-NH 2 as filler in CO 2 /CH 4 separation. A low MOC-1-4F loaded MMM (MOC-1-4F-2.17%) exhibited 57% improved CO 2 permeability (1228 barrer) in comparison with 6FDA-DAM membrane, and the CO 2 /CH 4 selectivity reached 22, surpassing the 2008 Robeson upper-bound. The plasticization effect was significantly alleviated in MOC-1-4F-2.17%, indicating that the MOC-1-4F-2.17% is potential for CO 2 /CH 4 separation. This work demonstrates that the gas separation performance of MOC-based MMMs could be fine-tuned by the structural tailoring of MOCs.
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Peiyu Jia,Junjie Liu,Jingjing Kong,Mingming Hu,Ning Qi,Zhiquan Chen,Shan Xu,Nanwen Li
Two series of 6FDA-based co-polyimide membranes were synthesized by adding different diamine monomer containing special functional groups: APAF (containing OH) and DABA (containing -COOH). The ODA/APAF and ODA/DABA series were heat treated at 450 °C and 350 °C, respectively. Thermal rearrangement of polymer chain segments is confirmed in ODA/APAF membranes by infrared spectroscopy, while addition of DABA in ODA/DABA membranes causes decarboxylation crosslinking. Positron lifetime measurements reveal existence of ultramicropores in polyimides. The thermal rearrangement in ODA/APAF membranes induces remarkable increase in both size and number of ultramicropores and therefore increase in fractional free volume (FFV), but the crosslinking in ODA/DABA causes significant decrease in both size and number of ultramicropores. The increase in FFV is favorable for gas permeation, but too large size of the micropore drastically deteriorates the gas selectivity. Finally, the ODA/APAF(3:7) shows a high CO 2 permeability of 127.4 Barrer with CO 2 /CH 4 selectivity of 34.2, which surpasses the 1991 Robeson upper bound. Besides, the ODA/DABA(3:7) exhibits a H 2 permeability of 22.6 Barrer with H 2 /CH 4 selectivity of 256.8, which also exceeds the 1991 Robeson upper bound. Our results indicate that the gas permeability and selectivity of polymer membranes can be effectively adjusted by tailoring the ultramicropore structures, and positron can provide precise information about micropores.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Shuaizhen Li,Zhibo Zheng,Siwei Liu,Zhenguo Chi,Xudong Chen,Yi Zhang,Jiarui Xu
High-efficiency heat-dissipation materials are in urgent need in microelectronics industry in 5G era. However, large-scale, low-cost, and high-efficiency preparation technologies still have great challenges. Here, ultrahigh thermal and electric conductive graphite films prepared by graphite-phase carbon nitride (g-C 3 N 4 ) catalyzed graphitization of polyimide film (PI) were reported for the first time. The graphite film obtained from 0.25 wt% g-C 3 N 4 catalyzed polyimide graphitization (G0.25) has homogeneous and perfect graphene structure and state-of-the-art properties. The d -spacing of the graphite layers is about 0.335 nm, which is similar to the ideal layer thickness of graphene (0.334 nm). The thermal conductivity is 1781 W·m −1 ·K −1 and the conductivity is 1.63 × 10 6 S·m −1 , which is 1.49 and 2.18 times of graphite film from pure PI film, 1.94 and 2.34 times of graphite film from commercialized Kapton film (I-film), respectively. The thermal conductivity of G0.25 film is 4.52 times of Cu and 7.46 times of Al. More importantly, the addition of g-C 3 N 4 can reduce the graphitization temperature from 2800 to 2500 ℃, which can reduce the energy consumption by 20.5% in the whole polyimide graphitization process. The developed preparation technology has important guiding significance and very attractive industrial application value for the preparation of large-scale, low cost and high-quality heat dissipation materials.
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高影响因子
TRIBOLOGY INTERNATIONAL
·
2021
·
IF 4.872
Xinle Yao,Sen Liu,Zhongying Ji,Rui Guo,Chufeng Sun,Yuxiong Guo,Xiaolong Wang,Qihua Wang
Three-dimensional (3D) target-region-lubrication printing of photosensitive polyimide (PSPI) filled with polytetrafluoroethylene (PTFE), i.e., PSPI-PTFE, with excellent tribological properties for self-lubricating devices was realized by digital light processing of PSPI-PTFE ink and thermal post-treatment. The 3D-printed PSPI-PTFE composites exhibited the friction coefficients and wear rates sharply reduced by 88% and 98%, respectively, and good mechanical properties , thermal stability and interlayer bonding as well. Importantly, the surfaces with lubricating only in regions where needed were readily realized due to the layer-by-layer manufacturing manner of 3D printing . As proof-of-concept, a target-region-lubricating bearing was demonstrated successfully, which run stably with a speed ranged from 60 to 180 rpm/min, indicating that the 3D-printed PSPI-PTFE composites are suitable for fabricating devices with complex and special shapes.
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高影响因子
Journal of Materials Chemistry C
·
2023
·Vol. 12
·期 1
·276-285
·
IF 6.4
Binzhe Tan,Dongya Guo,Zhirong Tao,Zhibo Chen,Zhijian Lv,Guozhang Wu,Yu Lin
Two-dimensional MXene materials show great potential for electromagnetic interference (EMI) shielding application because of their superior electrical conductivity. However, the susceptibility to oxidation and the mechanical brittleness of MXenes greatly limit their extensive application. Herein, an ultrathin flexible polyimide (PI)/Ti3C2TX composite film with a nacre-like lamellar structure is successfully prepared using a simple vacuum filtration and thermal imidization process. Owing to the addition of PI, the composite film exhibits excellent mechanical properties with a tensile strength of 114.9 MPa and a fracture strain of 3.0%. Moreover, the nacre-like lamellar structure is conducive to multiple internal reflections, giving rise to the absorption of electromagnetic waves. The PI/Ti3C2TX composite film exhibits an outstanding EMI shielding effectiveness of 37 dB in the X-band range with an ultrathin thickness of only 15 μm. Furthermore, PI serves as an antioxidation coating, and its EMI shielding performance is maintained even when the composite film is exposed to various harsh environments. Therefore, the resulting composite film exhibits excellent EMI shielding stability and durability, which enables the potential application of high-performance EMI shielding materials against harsh environments.
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高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Jun Cao,Chunjie Yan,Zefan Chai,Zhigang Wang,Minghe Du,Gen Li,Huanwen Wang,Heng Deng
Laser-induced graphene (LIG) has been extensively investigated for electrochemical energy storage due to its easy synthesis and highly conductive nature. However, the limited charge accumulation in LIG usually leads to significantly low energy densities. In this work, we report a novel strategy to directly transform natural rhodochrosite into ultrafine manganese dioxide (MnO 2 ) nanoparticles (NPs) in the polyimide (PI) substrate for high-performance micro-supercapacitors (MSCs) and lithium-ion batteries (LIBs) through a scalable and cost-effective laser processing method. Specifically, laser treatment on rhodochrosite/polyimide precursors induces the thermal explosion, which splits rhodochrosite (10 μm) into MnO 2 NPs (12–16 nm) on the carbon matrix of LIG due to the sputtering effect. Benefiting from largely exposed active sites from the ultrafine MnO 2 and the synergetic effect from highly conductive LIG, the MnO 2 /LIG MSCs show a high specific capacitance of 544.0 F g −1 (154.3 mF cm −2 ; 14.16 F cm −3 ) at 3 A/g and 82.1% capacitance retention after 10,000 cycles at 5A/g, in contrast to pure LIG (<100 F g −1 ). Moreover, the MnO 2 /LIG-based LIBs show the highest reversible discharge capacity of ∼1097 mAh g −1 at 0.2 A/g and ∼ 866.4 mAh g −1 at 1.0 A/g. This study opens a new route for synthesizing novel LIG-based composites from natural minerals.
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PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2021
·Vol. 56
·期 15
·9344-9355
·
IF 4.22
Fang Dan,Yan Bin,Agarwal Seema,Xu Wenhui,Zhang Qian,He Shuijian,Hou Haoqing
The separator is an important component for energy storage devices. At present, the membranes for supercapacitors are rare, especially the ones that work with an alkaline electrolyte. Herein, a type of flexible and highly porous polymer hybrid nanofiber membrane was prepared via a facile electrospinning process and served as a separator for supercapacitor’s work with strong alkaline electrolyte. As obtained, poly[poly(2,5-benzophenone)]bibenzopyrrolone/polyimide (PBPY/PI) membrane showed good thermal stability, high mechanical strength, large electrolyte uptake (452%), and fast ion conductivity (0.68 mS/cm). Moreover, PBPY/PI membrane exhibited excellent alkali resistance. The supercapacitor assembled with PBPY/PI membrane showed much better performance than those assembled with a commercial polypropylene membrane and electrospun polyimide nanofiber membrane and was found without capacitance loss after charge/discharge at 30 A/g for 10,000 cycles at 80 °C. The PBPY/PI membrane is a good candidate with temperature resistance and alkali resistance for high-performance supercapacitors.
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高影响因子
MACROMOLECULAR MATERIALS AND ENGINEERING
·
2021
·Vol. 307
·期 2
·2100645
·
IF 4.367
Weiwang Chen,Sha Liu,Yueyan Sun,Xiaomeng Zhou,Fenglei Zhou
Polyimide aerogels are promising for diverse applications owing to their nano-porous structure and superior properties. However, the shrinkage of melamine-crosslinked polyimide (MPI) aerogels has greatly compromised their performance in practical applications. In this study, supercritical drying with ethanol rather than CO 2 is employed to enhance their in-use shape stability at high temperatures. The structure, thermal insulation, mechanical strength of the resultant aerogels as well as their shape stability are characterized. Experimental results reveal that the shape stability of MPI aerogels during use is greatly improved thanks to the in-advance baptism of supercritical ethanol drying. The aerogel shrinks by only 2.64 vol.% after being treated at 280 °C for 72 h. Besides, the MPI aerogel shows enhanced compressive strength and can easily support a load more than 20 000 times its own weight. The thermal conductivity of these aerogels varies from 0.034 to 0.046 W m −1 k −1 , indicative of remarkable performance in thermal insulation. In addition, the aerogels that started to decompose at as high as 500 °C also perform well in thermal stability and char forming. It can be envisaged that the developed MPI aerogels with greatly improved in-use shape stability may have broad prospects for thermal insulation at high temperatures.
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高影响因子
TRIBOLOGY INTERNATIONAL
·
2021
·
IF 4.872
Lisong Dong,Jian Wu,Danyang Cao,Xin Feng,Jiahua Zhu,Xiaohua Lu,Liwen Mu
Liquid metal (LM) can be well distributed in polyimide (PI) coatings by ultrasonic shear into 1–2 μm diameter. The LM incorporated PI (PI-LM) coatings show remarkably enhanced tribological properties when the coating slide against GCr15 steel ball at room temperature, while the mechanical properties are slightly reduced. When the filling amount is 8%, the wear is just 10% of pure PI and the friction coefficient can be reduced by 31.6%. During friction process , the LM microspheres are squeezed to the frictional interface and form a transfer film together with PI debris, achieving lower wear and friction coefficient. These results show that PI-LM coatings have high potential as advanced self-lubricating materials.
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高影响因子
危险品化学品经营许可证（带存储）