MOLECULES
·
2023
·Vol. 28
·期 13
·4889
·
IF 4.6
Meng Lian,Feng Zheng,Lingbin Meng,Fei Zhao,Jun Liu,Jimei Song,Qinghua Lu
Heteroaromatic polyimides (PIs) containing benzimidazole have attracted tremendous attention due to their positive impact on the properties of PIs. Some research on PIs containing 4,4′-[5,5′-bi-1H-benzimidazole]-2,2′-diylbis-benzenamine (4-AB) has been reported. However, reports are lacking on homo-polyimides (homo-PIs) containing 3,3′-[5,5′-bi-1H-benzimidazole]-2,2′-diylbis-benzenamine (3-AB), which is one of the isomers of4-AB. In this paper, the influence of amino groups’ positions on the performance of homo-PIs was investigated. It was found that the net charge of the amine N group in4-ABwas lower than that of3-AB, resulting in higher reactivity of4-AB. Consequently, PIs containing4-ABdisplayed better mechanical performance. Molecular simulation confirmed that3-ABand its corresponding PI chain exhibited distorted conformation, leading to the PI films containing3-ABhaving a lighter color. In addition, the3-ABstructure was calculated to have higher rotational energy compared to4-AB, resulting in a higher glass transition temperature (Tg) in PIs prepared from3-AB. On the other hand, PIs containing4-ABexhibited a higher level of molecular linearity, leading to a lower coefficient of thermal expansion (CTE) compared to PIs prepared from3-AB. Furthermore, all PIs showed higher thermal stability with a 5% weight loss temperature above 530 °C andTghigher than 400 °C.Keywords:heteroaromatic polyimides;isomeric diamine;bis-benzimidazole
研究领域:
材料科学
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化学工程
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DOI
PubMed
高影响因子
Materials Today Communications
·
2023
·
IF 3.8
Miao Jiang,Chao Xiao,Xusheng He,Huichao Du,Yanyan Wang,Xin Ding,Xian Zhang,Xiaofei Li,Kang Zheng,Xianglan Liu,Lin Chen,Xingyou Tian
Functional textiles with efficient sweat releasing and thermal insulating play a pivotal role in maintaining physiological comfort in cold winter. However, the breathability and warmth have conflicting structural demands on the conventional fabric. Here, a porous polyimide film (PIF) with tunable sweat release capability was prepared by growing a graphene layer through laser-ablation strategy. Jungle-like graphene layer offers the porous PI film with distinct advantages, including a desired super hydrophobic performance (water contact angle =153°), rapid air permeability (1572 g/m 2 ·24 h), quick drying function based on high photo-thermal and electro-thermal conversion efficiency, and outstanding thermal insulating capability (0.033 W/m·K). Moreover, the graphene layer can also be custom printed into various patterns, which expanded the application scenarios for wearable flexible electronics. Overall, this Janus design offered insight into the proactive control of sweat release and heat transfer within the hierarchical and interconnected network, providing promising benefits to the development of multifunctional drying and warming textiles.
研究领域:
材料科学
·
纺织工程
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DOI
高影响因子
HIGH PERFORMANCE POLYMERS
·
2022
·
IF 1.73
Yihao Nie,Xibin Yi,Xinfu Zhao,Shimo Yu,Jing Zhang,Xiaochan Liu,Sijia Liu,Zhipeng Yuan,Minna Zhang
The cost of CO2 separation and energy consumption can be decreased through the use of CO2 adsorption. Due to the electron-rich heteroatoms in its network, polyimide (PI) has a remarkable affinity for CO2. Polyethylene glycol (PEG) can increase the layer spacing of polymers, so as to change the mass transfer of CO2 in it. Furthermore, the ether bond (-O-) in PEG has good affinity for CO2. In this study, PEG-1000 was introduced into PI aerogel by mild sol-gel method at low temperature, and freeze-drying was used to produce PI/PEG composite aerogels with directional pore structure. The effect of PEG-1000 content and directional pore structure of the PI/PEG composite aerogels on CO2 adsorption performance were further studied. The L-PI/PEG-4 composite aerogel, which contains 4 g PEG and is directionally frozen in liquid nitrogen, has a CO2 adsorption capacity of 16.76 cm3/g at 25°C and 1 bar. L-PI/PEG-4 aerogel also exhibits high CO2/N2 selectivity and adsorption cycle stability.
研究领域:
材料科学
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环境科学
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化学工程
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DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2023
·
IF 6.2
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.
研究领域:
材料科学
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电气工程
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DOI
高影响因子
ACS Sustainable Chemistry & Engineering
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2023
·
IF 8.4
Zishang Tian,Qi Zhao,Xingchen Liu,Yingxiong Wang,Jie Zhao,Yuqi Wang,Xianglin Hou
Aromatic polyimide (PI) is characterized by rigid chains and strong interchain interactions, resulting in poor solubility and non-melting of polymers, so chemical recovery of PI is challenging. Herein, ethylenediamine (EDA) was successfully used for the aminolysis of PI on the surface of flexible printed circuit boards (FPCBs). The PI can be completely degraded at 50 °C for 40 min at a revolution speed of 200 rpm, and the epoxy adhesive and flexible copper clad laminate sheet were separated by simple filtration. The degradation mechanism of PI was proposed and verified by the density functional theory (DFT) method. Intermolecular hydrogen bonding and the vicinal amino moiety of EDA play an important role in activating nucleophiles. DFT calculations show that the formation of the six-membered ring transition state is the rate-determining step during the breaking of the amide bonds. The Gibbs activation energy and the Gibbs reaction energy are 22.90 and 11.73 kcal/mol, respectively. This study provides guidance for the degradation of PI and the recovery of FPCBs.
研究领域:
材料科学
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化学工程
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环境科学
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产品关联
DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2023
·
IF 2.5
Chen Weiwang,Wan Mengmeng,Liu Sha,Tang Yating,Xu Qian
Melamine-crosslinked polyimide (MPI) aerogels are promising for diverse applications owing to their economical cost and impressive performance. However, MPI aerogels tend to suffer severe shrink in the processes of preparation and practical applications. Their upgrades, i.e., carbon foam-reinforced polyimide (CF-PI) aerogel composites, therefore were proposed in this study, to address this issue. The structure, thermal insulation of the resultant composites as well as their mechanical strength were characterized. The CF-PI aerogel composites were observed to have low shrinkage (as low as 9.25 vol.%) and low thermal conductivity (21 mW m −1 k −1 –34 mW m −1 k −1 ), indicative of significantly improved shape stability and exceptional thermal insulation capability. Besides, these aerogel composites also performed well in thermal stability, and did not decompose unless the temperature exceeds 400 °C. All these advantages contribute to the broad application prospects of thus aerogel composites in many aspects, such as thermal insulation for high temperatures, and so on. Graphical Abstract The composite is apparently composed of carbon foam and PI aerogel. Of the two, the carbon foam itself serves as a support frame, and PI aerogel is filled inside as the functional component. When the polymer concentration increases from 4 to 8%, the shrinkage of CF-PI aerogel composites gradually increases.
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DOI
高影响因子
EUROPEAN POLYMER JOURNAL
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2023
·
IF 6
Bo Xu,Rui Feng,Tingting Zhao,Ling Zhou,Yanyun Ju,Jiaqi Chen,Qimeng Zhang,Lijie Dong
High-performance polyimide (PI) films with excellent ultraviolet (UV)-resistant radiation and low dielectric constant ( k ) properties are ideal spacecraft antenna substrates in space applications. However, conventional commercial PI films like Kapton® applied in the aerospace field are inevitably subjected to the harsh UV radiation environment, leading to their structural damage and performance failure. Herein, a type of “self-sacrificial” micro-branched crosslinked PI films were fabricated by employing tris(4-aminophenyl)amine (TAPA) intrinsically containing the C-N bonds to crosslink linear pure fluorinated PI (FPI), where TAPA functioned as the dual roles of crosslinker and creating “self-sacrificial” local deep traps of C-N bonds in crosslinked sites. Consequently, abundant local deep traps of C-N bonds in crosslinked sites could capture energy from UV-rays to prevent the destruction of PI molecular main chains, thus the crosslinked FPI-TAPA films exhibited better UV-resistant radiation properties than that of pure FPI films and commercial PI films. And the crosslinked film showed least k of 2.53 and least dielectric loss of 0.006 at frequency of 1 MHz owing to the introduction of micro-branched crosslinked structure. Additionally, a high breakdown strength of 522 MV/m, as well as a high tensile modulus of 3.03 ± 0.07 GPa, was achieved, much better than the value of pure FPI film. This work provides a novel and facile approach to fabricate high-performance PI films with excellent UV-resistant properties, exhibiting great potential application in aerospace and microelectronics industries.
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高影响因子
Coatings
·
2023
·Vol. 13
·期 10
·1726
·
IF 3.4
Lei Chen,Weiyu Luo,Yima He,Lizhen Huang,Jinjie Xu,Kaixin Li,Yonggang Min
The development of renewable polymers as alternatives to the petroleum-based ones has received significant attention due to the increasing depletion of fossil oil and the associated environmental concerns. In this study, a semi-biomass-based polyimide (PI) film was successfully synthesized, using biomass-derived furfural (HMFA) as one of the raw materials. A two-step approach was first developed for this process: (1) conversion of HMFA to 3,3,4,4-biphenyltetracarboxylic acid dianhydride (BPDA) and (2) polymerization of BPDA with p-phenylenediamine (PPD) to form a PI film. The fabricated PI film demonstrated excellent properties, such as a high thermal decomposition temperature up to 600 °C, a satisfactory glass transition temperature (Tg) exceeding 365 °C, a coefficient of thermal expansion (CTE) of ≈30 ppm/K, a tensile strength greater than 120 MPa, a dielectric constant value below 3.4, a dielectric loss value of less than 0.02, and a 24 h water absorption rate below 0.8%. These performances are comparable to the petrochemical-based PI. This work offers a promising strategy for utilizing biomass-derived materials in polyimide synthesis and would drive a new wave of advancements in polymer science.Keywords:furfural;BPDA;polyimide;biomass;renewable polymer
研究领域:
材料科学
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聚合物化学
·
可持续材料
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DOI
高影响因子
ACS Applied Polymer Materials
·
2023
·
IF 5
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.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
POLYMER TESTING
·
2023
·
IF 5.1
Wenchao Zhang,Min Jiang,Feng Guan,Shiyu Liu,Liangjun Wang,Yanpeng Li,Dong Yue,Jialong Li,Xiaoxu Liu,Yu Feng
High-performance polymer dielectrics are critical for high-tech fields such as electrical insulation and aerospace. Nevertheless, it is still challenging to achieve simultaneous improvements in both dielectric constant and breakdown strength in polymer dielectrics. In this work, Al 3+ substitution Si 4+ in SiO 2 by high-temperature sintering to create hole traps to obtain the acceptor-doped fillers Si 1-0.75x Al x O 2 (SA (x mol%)), and polyimide (PI) dielectric containing SA fillers with different contents were synthesized using in-situ polymerization. The hole traps in the fillers modulate the electrical behavior of the polymer dielectric, thereby significantly increasing the dielectric constant and breakdown strength by modulating the polarization behavior and capture carriers. Among them, the dielectric constant of the 1.25 vol% SA (1.5 mol%)/PI composite was increased to 3.60 at 1 Hz, and the breakdown strength E b reached 581.5 kV/mm. This work provides a new synthesis strategy for simultaneously achieving high insulation and high polarization of polymer dielectric.
研究领域:
材料科学
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电气工程
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DOI
高影响因子
POLYMER ENGINEERING AND SCIENCE
·
2023
·Vol. 63
·期 7
·1953-1960
·
IF 3.2
Guiqing Zhao,Xin Mu,Dandan Ma,Shuhong Wang,Jiaqi Pan,Jiwen Cui,Meili Qi
With the advent of 5G era, the high millimeter-wave frequency band, poor signal penetration and large loss make 5G communication more dependent on low dielectric constant materials. Therefore, the research and development of low dielectric polymer materials has become a hot spot in recent years. With its good chemical corrosion resistance, thermal stability, high dispersion and high mobility, titanium dioxide (TiO 2 ) as a high function fine inorganic material is doped in polymer systems to improve the electrical properties of polymer composites. In recent years, a large number of studies have used spherical TiO 2 nanoparticles doped on the polymer matrix, however, there is almost no research on doping nanolinear TiO 2 nanoparticles on the polymer matrix. Here, TiO 2 nanowires were prepared by hydrothermal method, and the prepared TiO 2 nanowires were added to polyimide (PI). TiO 2 /PI monolayer and three-layer composite films with good dielectric and mechanical properties were prepared by in-situ polymerization. Fourier transform infrared spectoscopy, scanning electron microscopy and X-ray diffraction were used to characterize the structure and test the properties of the composites. During the initiation process, the thermal initiation reaction of the composite membrane was completed. The composite film with good mechanical properties and excellent dielectric properties were obtained by adding titanium oxide nanowires, which can meet the requirements of its use in the field of microelectronic devices.
研究领域:
材料科学
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电子工程
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DOI
高影响因子
ACS Applied Materials & Interfaces
·
2023
·
IF 9.5
Chang-Heng Li,Zhengyong Huang,Junping Lin,Tingting Hou,Yunlong Zi,Jian Li
As a clean, sustainable energy source, sound can carry a wealth of information and play a huge role in the Internet of Things era. In recent years, triboelectric acoustic sensors have received increasing attention due to the advantages of self-power supply and high sensitivity. However, the triboelectric charge is susceptible to ambient humidity, which reduces the reliability of the sensor and limits the application scenarios significantly. In this paper, a highly moisture-resistant fluorinated polyimide composited with an amorphous fluoropolymer film was prepared. The charge injection performance, triboelectric performance, and moisture resistance of the composite film were investigated. In addition, we developed a self-powered, highly sensitive, and moisture-resistant porous-structure acoustic sensor based on contact electrification. The detection characteristics of the acoustic sensor are also obtained.
研究领域:
材料科学
·
传感器技术
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DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）