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Sara Escorihuela, Lucía Valero, Alberto Tena, Sergey Shishatskiy, Sonia Escolástico, Torsten Brinkmann, Jose Manuel Serra
Three polyimides and six inorganic fillers in a form of nanometer-sized particles were studied as thick film solution cast mixed matrix membranes (MMMs) for the transport of CO₂, CH₄, and H₂O. Gas transport properties and electron microscopy images indicate good polymer-filler compatibility for all membranes. The only filler type thatdemonstrated good distribution throughout the membrane thickness at 10 wt. % loading was BaCe0.2 Zr0.7 Y0.1 O₃ (BCZY). The influence of this filler on MMM gas transport properties was studied in detail for 6FDA-6FpDA in a filler content range from one to 20 wt...
December 9, 2018: Membranes
Hengzhen Feng, Wenzhong Lou, Dakui Wang, Fuquan Zheng
The traditional silicon-based micro-electro-mechanical systems (MEMS) safety and arming (S&A) device fuze cannot isolate abnormal outputs in the detonation environment, which creates hazards for personnel. To address this problem, we report the design of a MEMS S&A device with integrated silver, copper, nickel and polyimide (PI) films, which is based on the principle of a MEMS S&A device and uses copper azide as the primer. The MEMS S&A device was optimized using theoretical calculations of the explosion suppression mechanism performance in a detonation field, where the theoretical model was verified by dynamic simulation (LS-Dyna)...
December 10, 2018: Micromachines
Maria Vomero, Elena Zucchini, Emanuela Delfino, Calogero Gueli, Norma Carolina Mondragon, Stefano Carli, Luciano Fadiga, Thomas Stieglitz
Glassy carbon (GC) has high potential to serve as a biomaterial in neural applications because it is biocompatible, electrochemically inert and can be incorporated in polyimide-based implantable devices. Miniaturization and applicability of GC is, however, thought to be partially limited by its electrical conductivity. For this study, ultra-conformable polyimide-based electrocorticography (ECoG) devices with different-diameter GC electrodes were fabricated and tested in vitro and in rat models. For achieving conformability to the rat brain, polyimide was patterned in a finger-like shape and its thickness was set to 8 µm...
December 7, 2018: Materials
Lushi Kong, Yu Wang, Hongsheng Yu, Bingxue Liu, Shengli Qi, Dezhen Wu, Wei-Hong Zhong, Guofeng Tian, Jie Wang
Development of non-flammable separators with excellent properties is in urgent need by next-generation advanced and safe energy storage devices. However, it has been extremely challenging to simultaneously achieve fire-resistance, high mechanical strength, good thermo-mechanical stability and low ion-transport resistance for polymeric separators. Herein, to address all these needs, we report an in-situ formed core-shell silica@ silica-imbedded polyimide (in-situ SiO2 @(PI/SiO2 )) nanofabric as a new high-performance inorganic-organic hybrid separator...
December 13, 2018: ACS Applied Materials & Interfaces
Dae Kyom Kim, Sehwa Bong, Xuanzhen Jin, Kwang-Dong Seong, Minsik Hwang, Nam Dong Kim, Nam-Ho You, Yuanzhe Piao
Efficient strategies to prepare carbon materials with improved electrochemical performance for supercapacitor have been in great demand. Herein, we develop multiple-heteroatom-doped carbons (from single- to triple-doped) by pyrolysis of polyimide precursors using a facile in situ approach. This approach can be used to tune heteroatom compositions by controlling the desired polyimide monomer functional groups as well as introducing external doping sources into the polyimide precursor solutions. Various types of multiple-heteroatom-doped carbons such as N; N,S-; N,F-; N,S,B-; and N,F,B-doped carbon are synthesized...
December 13, 2018: ACS Applied Materials & Interfaces
Xinfu Zhao, Xinqiang Wang, Jian Zhang, Xibin Yi
A novel Z-scheme Polyimide (PI)/AgBr@Ag aerogel photocatalyst has been successfully synthesized by combining in-situ precipitation method and supercritical drying method. The as-prepared PI/AgBr@Ag-50 (50% of AgBr@Ag in PI/AgBr@Ag) aerogel photocatalyst exhibited excellent photocatalytic activity for oxytetracycline degradation with a rate constant of 0.025 min-1, which was 6.9 and 2.6 times as many as that of PI aerogel and AgBr@Ag nanoparticles, respectively. More significantly, PI/AgBr@Ag-50 aerogel photocatalyst showed stable cycling, which could be attributed to the high mechanical strength and 3-D network of PI aerogel...
December 9, 2018: Chemistry, An Asian Journal
Daniel P Armstrong, Richard J Spontak
Stimuli-responsive soft materials are becoming increasingly important in a wide range of contemporary technologies, and methods by which to promote thermal stimulation remotely are of considerable interest for controllable device deployment, particularly in inaccessible environments such as outer space. Until now, remote thermal stimulation of responsive polymers has relied extensively on the use of nanocomposites wherein embedded nanoparticles/structures are selectively targeted for heating purposes. In this study, an alternative remote-heating mechanism demonstrates that the dielectric and resistive thermal losses introduced upon application of an alternating current generate sufficient heat to raise the temperature of a neat polyimide by over 70 °C within ≈10 s...
December 11, 2018: Macromolecular Rapid Communications
Hanjun Wu, Huali Zhang, Weijun Zhang, Xiaofang Yang, Hong Zhou, Zhiquan Pan, Dongsheng Wang
In this work, a novel core-shell structured magnetic polyimide@layered double oxides (LDO) composites coating a porous polyimide (PI)-coated Fe3 O4 magnetic core and layered double hydroxide (LDH) has been successfully synthesized by solve-thermal synthesis and co-precipitation process. The magnetic PI@LDO composites were characterized by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), thermogravimetry analysis (TGA) and magnetic properties analysis. The composite materials displayed core-shell structure with flower-like morphology...
December 3, 2018: Chemosphere
Mengyao Yao, Xin Zhao, Junxian Zhang, Wenjun Tan, Jie Luo, Jie Dong, Qinghua Zhang
Porous carbons derived from metal-organic framework are promising materials for a number of energy and environmental related applications. To integrate the powder metal-organic framework derived carbon into feasible engineered materials, a facile strategy to fabricate integrated flexible film is developed by growth of metal organic framework nanoparticles on polyimide electrospun nanofibers following with calcination to fabricate freestanding porous carbon decorated carbon nanofiber membranes. Then vertically polyaniline nanowire arrays were uniformly deposited on the hierarchical porous carbon substrates by in situ polymerization...
November 30, 2018: Nanotechnology
Yugo Kubo, Hirokazu Tanaka, Yoshihiro Saito, Akira Mizoguchi
With commercialization of the 5th generation mobile communication system and the further spread of the Internet of Things, industrial innovation is arriving with new business fields related to concepts such as high-speed communication, self-driving vehicles, and remote medicine. One of the challenges is the realization of flexible devices with high-definition circuits, which requires new fabrication techniques for Cu films on polymer substrates to meet demands and an understanding of the Cu/polymer interfacial nanostructure to assure product quality...
December 3, 2018: ACS Applied Materials & Interfaces
S H Yim, Z Kim, S Lee, T H Kim, K M Shim
We designed a double-layered polyimide film heater where the direction of the injection current of each layer is opposite to that of the other layer to reduce the magnetic field. The width of the heater is 0.125 mm and the resistance is 21.2 Ω. This specially designed heater successfully demonstrated temperature controllability within 10 mK for an atomic cell in an atom spin gyroscope while minimizing the generation of the magnetic field to within 1 nT.
November 2018: Review of Scientific Instruments
Doo-Young Youn, Uihyun Jung, Muhammad Naqi, Seon-Jin Choi, Min-Goo Lee, Sungho Lee, Hi-Joon Park, Il-Doo Kim, Sunkook Kim
Real-time temperature monitoring of individual blood packages capable of wireless data transmission to ensure the safety of blood samples and minimize wastes has become a critical issue in recent years. In this work, we propose flexible temperature sensors using Ag nanowires (NWs) and a flexible colorless polyimide (CPI) film integrated with a wireless data transmission circuit. The unique design of the temperature sensors was achieved by patterning Ag NWs using a three-dimensional (3D) printed mold and embedding the patterned Ag NWs in the CPI film (p-Ag NWs/CPI film), which resulted in a flexible temperature sensor with electrical, mechanical, and temperature stability for applications in blood temperature monitoring...
November 29, 2018: ACS Applied Materials & Interfaces
Kyoungjun Choi, Amirhossein Droudian, Roman M Wyss, Karl-Philipp Schlichting, Hyung Gyu Park
Reliable and large-scale manufacturing routes for perforated graphene membranes in separation and filtration remain challenging. We introduce two manufacturing pathways for the fabrication of highly porous, perforated graphene membranes with sub-100-nm pores, suitable for ultrafiltration and as a two-dimensional (2D) scaffold for synthesizing ultrathin, gas-selective polymers. The two complementary processes-bottom up and top down-enable perforated graphene membranes with desired layer number and allow ultrafiltration applications with liquid permeances up to 5...
November 2018: Science Advances
Qinglan Zhao, Dongfang Yang, Cheng Zhang, Xuanhe Liu, Xin Fan, Andrew K Whittaker, Xiu Song Zhao
Redox-active polyimide materials hold a great promise for electrochemical energy storage applications, especially for flexible energy storage devices. However, the low utilisation efficiency due to poor electrical conductivity of the materials remains one of the greatest challenges. In this work, we designed and prepared polyimide-graphene composite materials and tested their electrochemical properties in sodium-ion capacitors. By manipulating the interfacial chemistry and interactions between the polyimide and graphene, composite electrode materials with different polyimide particle sizes and morphologies were obtained...
November 26, 2018: ACS Applied Materials & Interfaces
Guohua Sun, Guoqing Dong, Lushi Kong, Xiaona Yan, Guofeng Tian, Shengli Qi, Dezhen Wu
Herein, we demonstrate a strategy to improve the tensile strength, thermal safety issues, and electrochemical performance of an as-synthesized polyimide separator. By spraying the solution of a specific chemical constituent on both sides of a poly(amic acid) non-woven membrane followed by thermal treatment, a novel polyimide nanofibrous membrane with porous-layer-coated morphology was successfully fabricated by in situ self-bonding and micro-crosslinking technique. The self-bonding and micro-crosslinking techniques improve the tensile strength of the nanofiber membranes from 5 MPa to 28 MPa by forming a crosslinked network structure, thereby reducing the risk of nanofiber disassembly during long-term operation...
November 26, 2018: Nanoscale
Byeong-Cheol Kang, Tae-Jun Ha
There have been constant attempts as regards high-performance thin-film transistors (TFTs) by improving the charge injection between the source/drain electrode (S/D) and the channel. In this paper, we investigate the effect of the electric contact on the device performance of single-wall carbon nanotube (SWCNT) TFTs employing the suitable work function material. In order to realize the electric contacts for the dominant hole injection between the S/D and the SWCNT active channel, a high work function material of molybdenum trioxide (MoO x ) fabricated by an optimized process are utilized...
March 1, 2019: Journal of Nanoscience and Nanotechnology
Bin Chang, Jing Chen, Mingan Zhou, Xiaojie Zhang, Wei Wei, Bin Dai, Sheng Han, Yanshan Huang
A nitrogen-doped carbon layer coating on a 3D graphene framework (NCL@GF) was produced by the in-situ polymerization of a uniform polyimide layer on the graphene framework surface and a carbonization process. The NCL@GF exhibited a 3D macroporous structure with uniform N-doped porous carbon layers and a high 5.4 at. % nitrogen content, which not only effectively enhanced the active sites but also facilitated fast ion and electron transport in the 3D pathways. Consequently, the NCL@GF as the anode of a sodium-ion battery (SIB) exhibited a discharge capacity of 357 mAh g-1 at 0...
November 20, 2018: Chemistry, An Asian Journal
Young-Tae Kwon, Yun-Sung Kim, Yongkuk Lee, Shinjae Kwon, Minseob Lim, Yoseb Song, Yong-Ho Choa, Woon-Hong Yeo
Inkjet-printed electronics using metal particles typically lack electrical conductivity and interfacial adhesion with an underlying substrate. To address the inherent issues of printed materials, this paper introduces advanced materials and processing methodologies. Enhanced adhesion of the inkjet-printed copper (Cu) on a flexible polyimide film is achieved by using a new surface modification technique, a nanostructured self-assembled monolayer (SAM) of (3-mercaptopropyl)trimethoxysilane. A standardized adhesion test reveals the superior adhesion strength (1192...
November 19, 2018: ACS Applied Materials & Interfaces
Guangyuan Xu, Zahraa A Jarjes, Hsiang-Wei Wang, Anthony R J Phillips, Paul A Kilmartin, Jadranka Travas-Sejdic
Carbon nanomaterials possess superb properties and have contributed considerably to the advancement of integrated point-of-care chemical and biological sensing devices. Graphene has been widely researched as a signal transducing and sensing material. Here, a grass-like laser-scribed graphene (LSG) was synthesized by direct laser induction on common polyimide plastics. The resulting LSG grass was employed as a disposable electrochemical sensor for the detection of three neurotransmitters, dopamine (DA), epinephrine (EP), and norepinephrine (NE), and in the presence of uric acid and ascorbic acid as potential interferants, using differential pulse voltammetry and cyclic voltammetry...
November 29, 2018: ACS Applied Materials & Interfaces
Hom N Sharma, Matthew P Kroonblawd, Yunwei Sun, Elizabeth A Glascoe
Moisture sorption and diffusion exacerbate hygrothermal aging and can significantly alter the chemical and mechanical properties of polymeric-based components over time. In this study, we employ a multi-pronged multi-scale approach to model and understand moisture diffusion and sorption processes in polyimide polymers. A reactive transport model with triple-mode sorption (i.e., Henry's, Langmuir, and pooling), experiments, and first principles atomistic computations were combined to synergistically explore representative systems of Kapton H and Kapton HN polymers...
November 15, 2018: Scientific Reports
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