ACS Applied Polymer Materials
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2019
·
IF 0
Chao Qian,Tianwen Zhu,Weiwen Zheng,Runxin Bei,Siwei Liu,Dingshan Yu,Zhenguo Chi,Yi Zhang,Jiarui Xu
Surface hydroxylation was implemented on CaCu3Ti4O12 (CCTO) particles to improve their interface compatibility and dispersibility in polyimide matrix. The surface hydroxylated CCTO fillers (CCTO–OH) were obtained by treating the CCTO particles in the mixed solution of H2SO4 and H2O2. The experimental results showed that the CCTO–OH/polyimide (PI) composite films had higher dielectric permittivity and lower coefficient of thermal expansion (CTE) compared to those of the CCTO/PI composite films, which were mainly attributed to the good dispersion of CCTO–OH particles and the enhanced interfacial polarization between CCTO–OH particles and PI chains. Among these CCTO–OH/PI composite films, the composite film with 40 vol % CCTO–OH particle loading exhibited the highest dielectric permittivity (76.9, 102 Hz), and a low dielectric loss (0.2, 102 Hz) was maintained. The maximum discharge energy density of the CCTO–OH/PI composite film with 25 vol % CCTO–OH reached 1.31 J/cm3, which was almost twice that of pure PI (0.63 J/cm3). Further, the prepared CCTO–OH/PI composite films had excellent heat resistance and low CTE. The high-k property of the CCTO–OH/PI composites remained stable up to 300 °C, which is probably the most heat-resistant dielectric material reported in the literature and is absolutely critical for the manufacture of electronic devices facing extreme conditions.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2019
·Vol. 136
·期 39
·47991
·
IF 2.188
Dekang Cheng,Huan Wang,Bin Liu,Shan Wang,Yang Li,Yushuang Xia,Chuanxi Xiong
Flexible dielectric materials with high electric energy density and high-temperature resistant characteristic are of great importance for modern electronics and electrical systems. Herein, two-dimensional molybdenum disulfide (MoS 2 ) nanosheets were efficiently produced via liquid-phase exfoliation and then incorporated into polyimide (PI) to prepare MoS 2 /PI dielectric nanocomposites. Compared to the pristine PI, MoS 2 /PI nanocomposite films exhibited much larger dielectric permittivity while their dielectric losses still maintained relatively low levels. On the other hand, the Weibull breakdown strength of these nanocomposite films initially increased and then decreased with the increase in the MoS 2 content and gave rise to a maximum value of 395 MV m −1 at 1 vol % loading. Combination of the improved dielectric permittivity and breakdown strength makes the MoS 2 /PI nanocomposite film with 1 vol % MoS 2 possess an elevated energy density of about 3.35 J cm −3 . Moreover, good tensile and thermal properties of the nanocomposite films hold great promise for their applications in high-temperature and harsh conditions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47991.
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ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Zhimin Hao,Juntao Wu,Chaolu Wang,Jingang Liu
Particulate matter (PM) pollution is a serious threat to human health. Zeolitic imidazolate framework-8 (ZIF-8) is a kind of metal-organic framework, and ZIF-8 not only can capture PM2.5 efficiently but also possesses excellent chemical and thermal stability. In this study, ZIF-8-modified soluble polyimide (PI) nanofibrous membranes were prepared via an electrospinning process. As a result, the PI-ZIF membrane shows high PM2.5 filtration efficiency (up to 96.6 ± 2.9%), superior thermal stability (up to 300 °C), good transmittance, excellent mechanical properties, and low pressure drop. The prepared PI-ZIF membrane with excellent comprehensive property shows a promising application in PM2.5 capture, especially in harsh conditions.
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 53
·期 18
·12885-12893
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IF 2.993
Fei Zhifang,Yang Zichun,Chen Guobing,Li Kunfeng,Zhao Shuang,Su Gaohui
A glass fiber/polyimide (PI)/SiO 2 composite aerogel (FPS aerogel) was prepared by dispersing glass fibers in PI/SiO 2 hybrid sol derived from 4,4′-oxydianiline (ODA), pyromellitic dianhydride (PMDA) and tetraethoxysilane (TEOS) with supercritical CO 2 fluid drying technology. The SiO 2 primary particles were combined with PI chains which improved the strength of the composite aerogel, and the glass fibers inhibited the shrinkage deformation during the drying process by acting as the supporting skeletons. Effects of PI contents on the density, shrinkage, thermal conductivity and mechanical properties of the FPS aerogels were investigated. The as-prepared FPS aerogels had low densities (0.116–0.145 g/cm 3 ), high specific surface area (844–963 m 2 /g), low thermal conductivity (0.0268–0.0280 W m −1 K −1 at room temperature) and relatively high compression strength (0.12–0.29 MPa) with integrated nanostructures, fewer powders and stronger fiber/aerogel matrix interfaces. The density, the shrinkage, the thermal conductivity and the compression strength of the FPS aerogels increased with the increasing PI content. This research provided a new method employing PIs and glass fibers as strengthening phases to improve the mechanical properties of SiO 2 -based aerogels.
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高影响因子
APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Yang Pu,Shuang Zhu,Pohui Wang,Yuqin Zhou,Pan Yang,Sensen Xuan,Yaping Zhang,Hongping Zhang
A novel branched sulfonated polyimide/molybdenum disulfide nanosheets (bSPI/MoS 2 -ns) composite membrane was fabricated for vanadium redox flow battery (VRFB) application. Scanning probe microscope (SPM) and field emission-scanning electron microscope (FE-SEM) images verify the successful exfoliation of monolayer and a few layers of MoS 2 nanosheets. X-ray diffraction (XRD), attenuated total reflection-fourier transform infrared spectrometer (ATR-FTIR) and FE-SEM results demonstrate that bSPI, bSPI/MoS 2 -ns and bSPI/MoS 2 nanopowders (bSPI/MoS 2 -np) membranes are successfully prepared. Both thermogravimetric analysis/differential thermogravimetry (TGA/DTG) and ex-situ chemical stability testing results confirm bSPI/MoS 2 -ns membrane has improved thermal and chemical stabilities in contrast with pristine bSPI membrane. The bSPI/MoS 2 -ns membrane owns high proton conductivity (5.04 × 10 −2 S cm −1 ) and extremely low vanadium ion permeability (0.65 × 10 −7 cm 2 min −1 ), leading to its highest proton selectivity (7.75 × 10 5 S min cm −3 ) among all the membranes tested. Besides, during 500 times cycle charge–discharge test, the coulombic efficiency, energy efficiency and discharge capacity retention of VRFB using bSPI/MoS 2 -ns membrane are higher than or comparable to those of VRFB using Nafion 117 membrane. And the surfacial morphological integrity of bSPI/MoS 2 -ns membrane maintains better than reported pristine bSPI membrane after long-time VRFB usage. Above results indicate that the as-prepared bSPI/MoS 2 -ns membrane has great potential for VRFB application.
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ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Xin Li,Jin Wang,Yibo Zhao,Xuetong Zhang
Aerogels have been widely used in the fields like thermal insulation, energy storage, environmental remediation, catalysis, drug release, sensor, and cosmic dust collection, etc. Hydrophobic functionalization not only determines the surface energy and basic physical properties of the target aerogels but also be critical for their long-term stability due to their highly open-porous structures. However, there is still lack of facial and versatile methodologies for the hydrophobic functionalization of aerogels, especially for the nonsilica ones. Herein, two efficient fluorine-free strategies were developed to synthesize various hydrophobic and even superhydrophobic polyimide (PI) aerogels. First, superhydrophobic PI aerogels with contact angle higher than 150° were fabricated by the segregation self-assembly process between poly[4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride)-co-p-phenylene diamine] and poly[biphenyl-3,3′,3,4′-tetracarboxylic dianhydride-co-2,2′-dimethylbenzidine] (poly(BPDA-DMBZ)). These PI aerogels exhibited a lotus effect that water droplets could not wet the surface but could easily roll off. Second, various hydrophobic PI aerogels, including the well-documented superhydrophilic PI aerogels derived from DMBZ–BPDA and 4,4′-oxydianiline–BPDA, were synthesized by the density-induced hydrophilicity–hydrophobicity transition approach. These PI aerogels exhibited a petal effect that water droplets on the aerogel surface appeared spherical in shape, which could not roll off even when the aerogel was turned upside down. These two reported strategies might open new and straightforward ways to hydrophobic functionalization of other polymeric aerogel systems.
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ACS Sustainable Chemistry & Engineering
·
2018
·
IF 6.14
Qingguo Chi,Zhiyou Gao,Tiandong Zhang,Changhai Zhang,Yue Zhang,Qingguo Chen,Xuan Wang,Qingquan Lei
In recent years, polymer-based dielectric capacitors have attracted much more attention due to the advantages of excellent flexibility, light weight, and high power density. However, most studies focus on energy storage performances of polymer-based dielectrics at room temperature, and there have been relatively fewer investigations on polymer-based dielectrics working under high-temperature conditions, which is much closer to the practical applications. Besides, dielectric capacitors operating in a high-temperature environment require excellent temperature stability of structure and performance. In this paper, high-temperature-resistant polyimide (PI) is selected as the matrix material, and 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 (BZT–BCT) nanofibers are used as the filling phase. By analyzing the energy storage behaviors of BZT–BCT/PI composites at different temperatures, it can be found that when the doping content of BZT–BCT nanofibers is more than 1 vol % the dielectric strength of the composites drops sharply when the temperature increases from 25 to 150 °C, resulting in serious deterioration of energy storage properties. On the basis of this, a composite film with a sandwich structure has been designed, where BZT–BCT/PI with different volume fractions is the intermediate layer and hexagonal boron nitride (h-BN) with good thermal and insulating properties is introduced in the top and bottom layers with a content of 5 vol %. Consequently, the results have shown that the energy storage properties of the constructed sandwiched dielectric composite films exhibit excellent temperature stability. The maximum field strength of the composite film with a BZT–BCT content of 1 vol % in the intermediate layer is 360 and 350 kV/mm under temperatures of 25 and 150 °C, and the storage density is 2.3 and 1.83 J/cm3 respectively.
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DYES AND PIGMENTS
·
2018
·
IF 3.767
Ye Tian,Ying Song,Hongyan Yao,Huaxuan Yu,Haiwei Tan,Ningning Song,Kaixiang Shi,Bo Zhang,Shiyang Zhu,Shaowei Guan
Two novel solution-processable polyimide (PI-6FDA) and co-polyimide (CoPI-6FDA), with triphenylamine (TPA)-derived structure as electron donor units and trifluoromethyl-containing phthalimide as electron acceptor units, were designed and synthesized for polymer memory device application. The TPA branched structure was introduced into the CoPI-6FDA to modify the performance of the polymer memory devices. Compared with PI-6FDA, CoPI-6FDA based memory devices exhibit better memory performance in lower threshold voltage of −3.1 V, higher ON/OFF current ratios of 10 5 , and better operation stability and charge transfer complex stability. The effect of TPA branched structures on memory performance has been further explored by optoelectronic measurements and theoretical calculation. Moreover, the optical and electrochemical measurements reveal the charge transfer mechanism of the CoPI-6FDA and PI-6FDA, which is related to the electrical bistability. The introduction of TPA branched structures was proved as a suitable strategy to fabricate the polymer memory devices with high performance.
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高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2018
·
IF 4.514
Hao Feng,Xinliang Fang,Xiaoyun Liu,Qibing Pei,Zhong-Kai Cui,Shifeng Deng,Jinlou Gu,Qixin Zhuang
This study reports the synthesis and characterization of reduced polyaniline decorated reduced graphene oxide/polyimide (RGO@R-PANI/PI) nanocomposite films with enhanced dielectric properties and thermostability. The steric effects of R-PANI decorated on the surface of RGO not only prevented the aggregation of RGO but also improved the dispersion of RGO@R-PANI nanosheets in the PI matrix, leading to higher dielectric constant (ε) and lower dielectric loss (tanδ) of the RGO@R-PANI/PI nanocomposite films than those of the RGO/PI nanocomposite films. The highest dielectric constant (25.84) was observed in the 20 wt% RGO@R-PANI/PI nanocomposite film (the mass fractions of RGO was 3.44%) with a low dielectric loss of 0.11 at 1 kHz. Furthermore, the 5 wt% weight loss temperature of the 20 wt% RGO@R-PANI/PI nanocomposite films was 480 °C, indicating the nanocomposite films are good candidates for dielectric materials under extreme temperature.
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高影响因子
RSC Advances
·
2018
·Vol. 8
·期 20
·11119-11126
·
IF 2.936
Faqin Tong,Shuangshuang Chen,Zhao Chen,Xuemin Lu,Qinghua Lu
Enhancing the azimuthal anchoring energy of the aligning film is a key requirement to improve the quality of liquid-crystal displays. Based on the assumption of mesogenic side groups being able to align liquid-crystal (LC) molecules, we have designed a novel transparent polyimide bearing cyanobiphenyl mesogenic side chains, which has a similar structure to that of liquid crystal 5CB. A pyrimidyl diamine monomer with a cyanobiphenyl mesogenic unit was first synthesized, and then co-polymerized with 4,4′-diaminodiphenyl ether and 4,4′-oxydiphthalic anhydride. The obtained polyimide (PI) exhibited good thermal stability and mechanical properties, as well as high optical transparency with transmittance of up to 86% in the wavelength range 450–700 nm. By evaluating the adhesion force between PI films and LCs with a super-sensitive microelectro-mechanical balance system, we have verified that appending mesogenic groups on the side chains of PI strengthens intermolecular interactions between the LC and PI surfaces, thereby enhancing the surface anchoring energy. Compared with the unmodified PI, the anchoring energy of the derivatized PI was improved more than 2.2-fold. By virtue of its good transparency and strong anchoring energy, this PI would seem to be an ideal candidate as a LC alignment film, and the concept of mesogens aligning LCs may open a new door in the design of LC alignment films.
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CERAMICS INTERNATIONAL
·
2015
·
IF 2.605
M. Wang,W.L. Li,Y. Feng,Y.F. Hou,T.D. Zhang,W.D. Fei,J.H. Yin
BaTiO 3 nanowires/polyimide (BT-NWs/PI) and BaTiO 3 nanoparticles/polyimide (BT-NPs/PI) composites with low volume (≤10vol%) fraction of ceramic fillers were successfully prepared by in-situ dispersive polymerization. The BT-NWs were synthesized by a simple one-step hydrothermal method . The microstructure, dielectric properties , and energy storage density of the composites were studied. It was found that the two types of fillers were dispersed homogeneously in the PI matrix. Compared with BT-NPs/PI composites, the dielectric constant of composites filled by BT-NWs was larger at the same concentration. Stronger interfacial polarization mainly determined the dielectric properties that we observed on BT-NWs/PI composites. Furthermore, the energy storage density of the composites was significantly enhanced by BT-NWs, and energy storage density of 1.06 J/cm 3 was obtained under an electric field of 2200 kV/cm with the BT-NWs content of 2 vol%, which was 37% larger than that of the pure PI. The results indicate that the introduced wire-like ceramic fillers contribute to the enhancement of the dielectric properties and energy storage density of the composites.
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CHEMISTRY OF MATERIALS
·
2015
·
IF 8.354
Linli Xu,Shidong Jiang,Baopeng Li,Wenpeng Hou,Guoxing Li,Mushtaque A. Memon,Yong Huang,Jianxin Geng
Close-celled aromatic polyimide (PI)/graphene foams with low density and improved flexibility were fabricated by thermal foaming of poly(amic ester)/graphene oxide (PAE/GO) precursor powders. The PAE/GO precursor powders were prepared by grafting GO nanosheets with PAE chains, which led to efficient dispersion of the GO nanosheets in PAE matrix. Incorporation of GO resulted in an enhanced foaming capability of the precursor, i.e., enlarged cell size and decreased foam density. Notably, a decrease of 50% in the foam density was obtained via the addition of only 2 wt % GO in the precursor. In the foaming process, the GO nanosheets functioned as a versatile agent that not only provided heterogeneous nucleation sites but also produced gaseous molecules. By analyzing the foaming mechanism, the excellent features of GO in heat transfer, gas barrier, and strength reinforcement also facilitated to obtain large and uniform cells in the foams. In addition, the PI/graphene foams exhibited a prominent flexibility and enhanced flexural strength, as an elastic-to-nonelastic conversion of the initial stage of the compressive stress–strain curves was observed by increasing the content of graphene in the PI matrix and an increase of 22.5% in flexural strength was obtained by addition of 0.5 wt % GO in the precursor.
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