MOLECULES
·
2023
·Vol. 28
·期 24
·7987
·
IF 4.6
Yancheng Wu,Manyu Lian,Guotao Huang,Yangfan Zhang,Ningbo Yi,Liyong Tian,Feng Gan,Chunping Ma
Atert-butyldiphenylsilyl-containing polyimide (PI-OSi) has been established as a colorimetric and ratiometric chemosensor for rapid detecting fluoride ions (F−). The UV-vis absorbance ratio value (A322/A288) ofPI-OSiin a DMF solution displays a wide linear range change to F−concentrations with a detection limit (DL) value of 2.13 μM. Additionally, adding incremental amounts of F−to a DMF solution ofPI-OSishows an immediate color change to yellow and finally to green from colorless. More interestingly, the resultingPI-OSiplus F−system (PI-OSi·F) could detect trace water in DMF. The A292/A322value ofPI-OSi·F almost linearly increases with low water content, which suggests convenient quantitative sensing of trace water content in DMF. The DL value ofPI-OSi·F for sensing water in DMF is determined to be 0.00149% (v/v). The solution color ofPI-OSi·F returns to colorless when the water content increases, indicating thatPI-OSi·F can conveniently estimate water content in DMF by naked-eye detection. The detection mechanisms confirmed by an1H NMR study and a DFT calculation involve a F−-induced desilylation reaction ofPI-OSito form phenolate anion followed by protonation with trace water. Finally,PI-OSifilm was fabricated for the colorimetric detection of F−and water in CH3CN.Keywords:tert-butyldiphenylsilyl-containing polyimide;colorimetric and ratiometric chemosensor;fluoride ions;trace water
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PubMed
高影响因子
POLYMER
·
2023
·
IF 4.6
Long Ni,Yinfu Luo,Guanchun Wang,Liwei Yan,Shaoyu Qiu,Mei Liang,Shengtai Zhou,Huawei Zou
In this work, a facile microwave-assisted foaming and thermal imidization treatment method was proposed to fabricate flexible polyimide (PI)/rGO composite foams with anisotropic pore structures . The PI/rGO composite foams (PIF/rGO) were used as the starting derivatives to prepare carbon foams that demonstrated excellent anisotropic thermal insulation and electromagnetic interference (EMI) shielding applications. The directional growth of pore structures during the foaming period resulted in the formation of aligned ellipsoidal strip-like pore structure in the horizontal direction (i.e., perpendicular to the pore growth direction), which was attributed to the escape of foaming gases such as tetrahydrofuran , methanol and H 2 O. The homogeneous dispersion of rGO in the PI-derived carbon skeleton endowed corresponding carbon foams with excellent mechanical and thermal stability, high thermal insulation and electrical conductivity (σ) as well as absorption dominated EMI shielding performance. The σ and EMI shielding effectiveness (SE) of carbon foams showed an increasing trend with increasing rGO content. The σ, EMI SE and specific EMI SE of the carbon foams reached up to 33.0 S/m, 49.0 dB and 8792.8 dB/(g/cm 2 ) in the horizontal direction, respectively. Therefore, this work provided a facile strategy to fabricate lightweight and anisotropic pore structure rGO-containing PIFs and carbonized derivatives, which demonstrated promising applications in high-end industrial fields.
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Materials Today Physics
·
2023
·
IF 11.5
Xianzhe Sheng,Shuhuan Yun,Shengli Wang,Yusong Gao,Xinpei Zuo,Xing Miao,Xuetao Shi,Jianbin Qin,Zhonglei Ma,Guangcheng Zhang
The polyimide (PI) foams possess outstanding properties such as light weight, high temperature resistance, sound absorption and noise reduction, thermal insulation and flame retardant , etc. However, the currently reported PI rigid foams (PIRFs) exhibited poor mechanical properties and heat resistance due to their low crosslinking density , and could not be used for structural materials in areas such as aerospace and military ships, etc. Herein, the highly heat resistant and mechanically strong co-crosslinked polyimide/bismaleimide (PI/BMI) rigid foams were fabricated by the feasible and scalable capping precursor powder foaming method. The norbornene-end-capped polyimide oligomer (NEPIO) was melt copolymerized with 4,4′-bismaleimide diphenylmethane (BDM), incorporating the maleimide structure into the PI molecular chain and constructing the high-density PI/BMI co-crosslinking networks. Four different diamine monomers were used for the fabrication of co-crosslinked PI/BMI rigid foams. The results showed that the PI/BMI rigid foams using m -phenylenediamine (MPD) as diamine monomer exhibited the superior comprehensive performances, including outstanding heat resistance with high glass transition temperature ( T g ) of 386.1 °C and thermal degradation temperature ( T 10 wt% ) of 534.9 °C, as well as excellent compression strength of 6.58 MPa at room temperature and 6.32 MPa at high temperature of 200 °C with a mass density of 290 kg/m 3 , which surpassed all the previously reported PI rigid foams. Moreover, the PI/BMI rigid foams showed superior thermal insulation properties with ultra-low thermal conductivities at room temperature and 200 °C, as well as outstanding flame resistance with high limited oxygen index (LOI) of above 45%. The obtained co-crosslinked PI/BMI rigid foams showed promising application potentials as structural materials in aerospace, military ships, rail transportation and other high temperature resistant special fields.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Fuying Pei,Hongge Jia,Shuangping Xu,Mingyu Zhang,Yanqing Qu
Membrane separation is considered an effective technology for treating oily wastewater. Hydrophilic, underwater oleophobic water removal membranes prepared by electrostatic spinning have received significant attention due to their excellent antifouling properties, small pore blockage, and high permeation flux. Herein, a simple and effective method was proposed for fabricating fabrics with superhydrophilic and submerged superoleophobic properties. First, the materials were co-blended with sodium dodecyl benzene sulfonate by electrostatic spinning, and then the porous fiber membrane was obtained by a step-up temperature for thermal imidization. The obtained membranes showed superhydrophilic and underwater oleophobic properties and could separate oil–water emulsions with or without surfactant stabilization while also exhibiting certain retention of methylene blue dye. The separation efficiency was driven by gravity alone, and the oil–water separation efficiency was always above 98.5% for 10 separation cycles, with a separation flux of up to 700 L·m −2 ·h −1 . The modified membranes were tested and evaluated for various oil–water emulsions, and the separation efficiency was found to be consistently above 98.5%. In addition, the membranes showed satisfactory mechanical strength, high-temperature resistance, and excellent contamination resistance, suggesting that these membranes could serve as promising candidates for the treatment of industrial oil-in-water emulsions.
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高影响因子
POLYMER
·
2022
·
IF 4.432
Min Zhao,Caili Zhang,Yunxuan Weng,Pei Li
Thermal oxidative crosslinking results in the generation of oxygen bridges among polymer chains and helps regulate the membrane microstructure. Simultaneously, any strategy to increase the crosslinking sites of polyimide (PI) can improve the crosslinking efficiency and allow precise control of the pore structure of membranes. Phenolphthalein-based PIs are potentially suitable precursors for thermal oxidative crosslinking of membranes, since thermal treatment will result in the degradation of lactone ring leading to the generation of a pair of phenyl crosslinking sites. In this work, three phenolphthalein-based diamines with different structures were designed and synthesized. The three diamines were subsequently reacted with 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) to prepare phenolphthalein-based PIs. The original membranes were post-treated by thermal oxidation crosslinking at 400 °C and 425 °C, respectively; the lactone ring underwent decomposition, and the imide ring opened at the same time, resulting in the generation of multiple crosslinking sites and correspondingly improving the crosslinking efficiency. The effect of the side groups (−CH 3 , –CF 3 or unsubstituted) of phenolphthalein-based diamine and thermal treatment temperatures on the gas separation performance of phenolphthalein-based PI membranes were investigated. Wide-angle X-ray diffractometry (WAXD) and wide-angle X-ray scattering (WAXS) analysis demonstrated that the π-π stacking distance were improved. BTDA-FPP-425 had a CO 2 /CH 4 selectivity of 37.68. This thermal degradation along with thermal oxidative crosslinking strategy provides a promising approach for fabrication of CO 2 /CH 4 separation membrane .
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JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Jun Liu,Jun Long,Wenheng Huang,Wenjie Xu,Xiujuan Qi,Jinchao Li,Yaping Zhang
Vanadium redox flow battery (VFB) is promising for use as an energy storage/conversion device, however membrane imposes a limitation in enhancing the performance of VFB. Herein, a novel diamine monomer bis(2-trifluoromethyl-4-aminobenzene) amine containing imino groups is synthesized by nucleophilic substitution and reduction reactions. Then, we develop four branched sulfonated polyimide (I-bSPI) membranes with 40%–70% theoretical sulfonation degrees for application in VFB. The trade-off between proton conduction and vanadium ion blocking of I-bSPI membrane is broken, and the stability of I-bSPI membrane is also effectively enhanced owing to hydrogen bonds network and Donnan repulsion effect. Surprisingly, the proton selectivity of I-bSPI-50 membrane is 4.6 times that of commercial Nafion 212 membrane. In addition, I-bSPI-50 membrane exhibits superior coulomb and energy efficiencies to Nafion 212 membrane at 100–300 mA cm −2 . And I-bSPI-50 membrane has steady efficiencies and high capacity holding abilities during 600-time cycles. This work illustrates a promising pathway to obtain cost-effective membrane by hydrogen bonds construction strategy for VFB application.
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Journal of Materials Chemistry C
·
2022
·Vol. 10
·期 38
·14255-14264
·
IF 8.067
Xiaofei Li,Xin Ding,Yuhang Du,Chao Xiao,Yanyan Wang,Kang Zheng,Xianglan Liu,Lin Chen,Xingyou Tian,Xian Zhang
Photothermal actuators have received more and more attention due to their high efficiency, easy fabrication, and various implementation methods. In this work, we prepared a photothermal actuator via structural design using liquid metal (LM) particles and polyimide. Due to the flexibility of liquid metals, which is different from those of other rigid fillers, the photothermal actuator responds rapidly with a bending speed of 21.89° s−1, which exceeds those of most of the reported photothermal actuators. In addition, this work explored the photoactuation mechanism of the liquid metal/polyimide photothermal actuator and found that the difference in the thermal expansion coefficient was the main reason for the liquid metal content to be low. What's more, the photothermal actuator can mimic the creeping of caterpillars, the swimming of fish, and the lifting and falling of arms under a NIR laser. Besides, the photoactuators can be used as light-controlled switches to realize the remote and precise control of the circuit. Therefore, photoactuators are expected to be used in the fields of bionic systems and flexible robots, which enriches the research content of photoactuators and expands the application field of liquid metals.
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Journal of Materials Chemistry A
·
2022
·Vol. 10
·期 23
·12692-12701
·
IF 14.511
Chang Xu,Fan Gao,Jiajin Tang,Yanbo Yao,Tao Liu
Due to their highly efficient and broad-band optical absorption characteristics, different types of carbon materials, e.g., carbon black, carbon fibers, carbon foam, carbon nanotubes, graphene, etc., have been explored for the use as light absorbing materials in the emerging technology of interfacial solar-driven water evaporation. Nevertheless, the current approach for fabricating/integrating/assembling a highly efficient water evaporation system typically involves a tedious multi-step process, in which the light-absorbing materials are separately prepared by a sophisticated wet-chemistry approach and then integrated with the underlying insulation layer. Herein, we manifest a simple approach that relies on a direct laser writing carbonization (DLWc) method in conjunction with HNO3 oxidation treatment for fabricating multi-layer structured interfacial solar-driven water evaporation systems. With this approach, two different types of water evaporation systems are designed, fabricated, characterized and evaluated, which include the perforated hydrophobic carbon/polyimide/hydrophilic carbon tri-layer TLF system and an inverted V-shaped hydrophilic carbon/polyimide bi-layer BLV system. Depending upon the design schemes, the DLWc enabled interfacial solar-driven water evaporation systems achieve high water evaporation rate in the range of 1.11–1.73 kg m−2 h−1 with excellent long-term stability and mechanical robustness. The efficient, scalable and low-cost fabrication process and the excellent water evaporation performance of the DLWc enabled water evaporation systems make them highly promising in the niche application of compact, stand-alone and portable water purification use.
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Nanomaterials
·
2021
·Vol. 11
·期 11
·3038
·
IF 5.076
Tao Shi,Zhiheng Zheng,Huan Liu,Dezhen Wu,Xiaodong Wang
Electromagnetic (EM) and infrared (IR) stealth play an important role in the development of military technology and the defense industry. This study focused on developing a new type of multifunctional composite film based on polyimide (PI)/graphene/Fe3O4hybrid aerogel and polyethylene glycol (PEG) as a phase change material (PCM) for EM and IR bi-stealth applications. The composite films were successfully fabricated by constructing a series of PI-based hybrid aerogels containing different contents of graphene nanosheets and Fe3O4nanoparticles through prepolymerizaton, film casting, freeze-drying, and thermal imidization, followed by loading molten PEG through vacuum impregnation. The construction of PI/graphene/Fe3O4hybrid aerogel films provides a robust, flexible, and microwave-absorption-functionalized support material for PEG. The resultant multifunctional composite films not only exhibit high microwave absorption effectiveness across a broad frequency range, but also show a good ability to implement thermal management and temperature regulation under a high latent-heat capacity of over 158 J/g. Most of all, the multifunctional composite films present a wideband absorption capability at 7.0–16.5 GHz and a minimum reflection loss of −38.5 dB. This results in excellent EM and IR bi-stealth performance through the effective wideband microwave absorption of graphene/Fe3O4component and the thermal buffer of PEG. This study offers a new strategy for the design and development of high-performance and lightweight EM–IR bi-stealth materials to meet the requirement of stealth and camouflage applications in military equipment and defense engineering.Keywords:electromagnetic and infrared bi-stealth;phase change material;polyimide-based aerogels;graphene/Fe3O4hybrid;thermal regulation;microwave absorption
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高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Yan Li,Lu-Bin Zhong,Qi-Jun Zhang,Chao-Yang Guo,Bu-Qing He,Mohammad Younas,Yu-Ming Zheng
The quest for a highly breathable protective clothing with good barrier performance is rapidly rising, especially in the fight against the COVID-19 pandemic. However, commercial protective clothing usually experiences trade-off between air permeability and barrier performance. Herein, a highly breathable and durable polyimide (PI)-based protective clothing material with good barrier performance was fabricated by electrospinning. The structure of PI electrospun nanofibrous membranes (PI-ENMs) was optimized in terms of mechanical strength , filtration efficiency and air permeability. The results showed that the PI-ENM with 500 nm diameter prepared by electrospinning for 4 h had high filtration efficiency (96.13 %), low pressure drop (57.1 Pa) and high-quality factor (0.057 Pa -1 ). The optimized PI-ENM had a high bacterial filtration efficiency of 99.48 %, which meant that it would possess good microbial barrier performance in practical applications. Due to the low air resistance, the PI-ENM demonstrated a high air permeability of 265.44 mm s −1 , which was 40–160 times that of commercial protective clothing. An ultra-thin layer of polydimethylsiloxane (PDMS) was coated on the thermal stable PI-ENMs via chemical vapor deposition to obtain PI-ENM@PDMSs, of which the fire resistance was further enhanced without compromising filtration efficiency and resistance. Moreover, the PI-ENM@PDMSs exhibited strong hydrophobicity , robust mechanical strength, and excellent stability, and can be easily reused via common sterilization methods without impacting its protection performance. Therefore, PI-ENM@PDMSs is a promising candidate for reusable breathable protective clothing.
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高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2026
·
IF 5.1
Liqi Zhuang,Fengxia Zhai,Xinyu Wang,Xincheng Sun,Shicheng Zhao
A strategy based on the combined regulation of the DS and FFV of membranes. • The prepared membrane exhibits high proton conductivity and dimensional stability. • The BSPI-50 membrane exhibited a peak power density of 72.97 mW cm −2 . • The membrane exhibited good long-term stability in single-cell tests. The trade-off between proton conductivity and dimensional stability of sulfonated polyimide (SPI) proton exchange membranes (PEMs) greatly limits their practical application in direct methanol fuel cells (DMFCs). Herein, a strategy for regulating the proton conductivity and dimensional stability of copolymer membranes through the coupled regulation of the degree of sulfonation (DS) and fractional free volume (FFV) is proposed. By introducing bulky fluorene groups as side chains to regulate the FFV, a series of SPI PEMs with different DS and FFV were prepared. It is found that an appropriate balance between DS and FFV is critical for achieving high proton conductivity and dimensional stability. In particular, the BSPI-50 membrane achieves a proton conductivity of 113 mS·cm −1 at 80 ℃ while maintaining a low swelling ratio of 35.2 %. Molecular dynamics simulations reveal that FFV can be tuned by adjusting the content of fluorene units, as increased side-group content weakens intermolecular interactions between polymer chains. An appropriate balance between DS and FFV facilitates the formation of well-connected hydrophilic nanochannels, thereby promoting proton transport while maintaining dimensional stability. The BSPI-50 membrane delivers a peak power density of 72.97 mW·cm −2 in single cells and exhibits durability over 100 h of continuous operation, with a minimal voltage decay rate of 0.7 mV·h −1 . This work demonstrates that the combined regulation of DS and FFV provides an effective approach to balancing proton transport and dimensional stability, enabling the development of SPI PEMs with excellent overall performance for DMFCs. Download: Download high-res image (134KB) Download: Download full-size image
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DOI
高影响因子
POLYMER
·
2023
·
IF 4.6
Dandan Li,Zhaohui Lu,Zhao Ke,Ke Xu,Fengna Dai,Youhai Yu,Guangtao Qian,Chunhai Chen
Membranes with low dielectric constant and high moisture resistance are the key material for miniaturized and integrated communication equipment as an interlayer dielectric layer. Here, a series of cross-linked PI aerogel membranes were prepared by co-polymerization and scraping coating technology . The introduction of the fluorinated blocks and benzimidazole ring structures can consequently garner novel PI aerogel membranes with fascinating dielectric properties and outstanding moisture resistance. The dielectric constants of the sample membranes are as low as 1.33 at 1 KHz and 1.32 at 1 MHz with dielectric loss as low as 0.0079 at 1 KHz and 0.0035 at 1 MHz. The water contact angle can reach 107.35° with a surface roughness value of 30.428 nm. Moreover, the PI aerogel membranes have high specific surface area and excellent thermal and mechanical properties. The thermal conductivity as low as 35.4 mW m −1 K −1 at room temperature indicates excellent thermal insulation performance. PIAM-2 is suitable as an interlayer dielectric layer for electronic components under harsh environment. In addition, the influence of surface roughness on surface wettability was also elaborated on which can provide a feasible method for the preparation of low dielectric materials with moisture resistance.
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高影响因子
危险品化学品经营许可证（带存储）