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Development of enhanced multiwalled carbon nanotube (MWCNT) conductive polymeric nanocomposites by using acidified derivative of MWCNT as dispersant
摘要： The agglomeration of pristine multiwalled carbon nanotubes (MWCNTs) within a polymer matrix has largely limited the efficient conductive reinforcement of MWCNTs-based polymeric nanocomposites. In this paper, the pristine MWCNTs realized well-dispersed with the assistance of nitric acid acidified MWCNTs. The as-prepared hybrid MWCNTs were used to prepare hybrid MWCNTs buckypaper and hybrid MWCNTs/polyvinyl butyral (PVB) nanocomposites. The hybrid MWCNTs dispersion maintained good dispersing stability over 3 months. The fabrication of hybrid MWCNTs buckypaper shows that the intrinsic conductivity of the hybrid MWCNTs is 25.1 ± 0.2 S/cm, higher than the pristine ones of 23.3 ± 0.2 S/cm. The SEM images of hybrid MWCNTs/PVB nanocomposites show that hybrid MWCNTs are distributed homogenously in the PVB matrix. The conductive performance of nanocomposites is significantly enhanced with a low percolation of 0.44 ± 0.05 wt. % and a high critical exponent of 3.57.
关键词： MWCNTs,conductive reinforcement,multiwalled carbon nanotubes,dispersant,polymeric nanocomposites
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Improving Focusing Properties of Gradient Annular Metal Gratings of Terahertz Range
摘要： We report the design, fabrication, and experimental characterization of dense, monolithic, and planar arrays of externally-fed electrospray emitters with an integrated extractor grid and carbon nanotube ?ow control structures for low-voltage and high-throughput electrospray of the ionic liquid EMI-BF4 in vacuum. Microfabricated arrays with as many as 1900 emitters in 1 cm2 were fabricated and tested. Per-emitter currents as high as 5 μA in both polarities were measured, with start-up bias voltages as low as 470 V and extractor grid transmission as high as 80%. Maximum array emission currents of 1.35 mA (1.35 mA/cm2) were measured using arrays of 1900 emitters in 1 cm2. A conformal carbon nanotube forest grown on the surface of the emitters acts as a wicking structure that transports liquid to the emitter tips, providing hydraulic impedance to regulate and uniformize the emission across the array. Mass spectrometry of the electrospray beam con?rms that emission in both polarities is composed of solvated ions, and etching of the silicon collector electrode is observed. Collector imprints and per-emitter current–voltage characteristics for different emitter array sizes spanning three orders of magnitude show excellent emission uniformity across the array. Performance estimates of the devices as nanosatellite thrusters are provided.
关键词： Electrospray,carbon nanotubes,ionic liquid,MEMS,multiplexing,microfabrication
更新于2025-09-23 15:19:57
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Spectral analysis combined with nonlinear optical measurement of laser printed biopolymer composites comprising chitosan/SWCNT
摘要： Biopolymer composites based on two types of chitosan (chitosan succinate and low-molecular weight chitosan) with single-walled carbon nanotubes (SWCNT) were created by laser printing. SWCNT have good dispersibility in chitosan solutions and therefore, can form relatively homogeneous films that was shown in scanning electron microscopy images. For the studies film composites were formed under the action of laser radiation on aqueous dispersion media. Study of the nonlinear optical process during the interaction of laser radiation with a disperse media has shown that low-molecular chitosan has a large nonlinear absorption coefficient of 17 cm/GW, while the addition of SWCNT lead to a significant increase up to 902 cm/GW. The threshold intensity for these samples was 5.5 MW/cm2 with nanotubes. If intensity exceeds the threshold value, nonlinear effects occur, which, in turn, lead to the transformation of a liquid into a solid phase. Characterization of films by FTIR and Raman spectroscopy indicated arising molecular interactions between chitosan and SWCNT detected as a small frequency shift and a change in the shape of radial breathing mode (RBM). The results indicate the possibility using aqueous dispersion media based on chitosan and SWCNT to create three-dimensional films and scaffolds for tissue engineering by laser printing.
关键词： Tissue engineering,Carbon nanotubes,Nonlinear optical properties,Chitosan,Spectroscopy
更新于2025-09-23 15:19:57
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Arrays of Carbon Nanotubes in a Field of Continuous Laser Radiation
摘要： A numerical analysis of the phase-matching conditions during the incidence of one or two counterpropagating laser beams on an ordered array of single-walled carbon nanotubes (CNTs) is performed. The conditions for the generation of slow surface plasmon waves of the terahertz (THz) and far infrared range propagating along the nanotubes of the irradiated array are determined. It is shown that the plasmon frequency can be controlled by changing the angle of incidence of laser radiation on the structure under study. Thus, it is possible to fulfill the condition of longitudinal resonance, in which each array nanotube is a dipole antenna radiating at the plasmon frequency. In this case, the array forms a system of a large number of in-phase emitters, which allows increasing the efficiency of conversion of laser radiation into THz radiation in comparison with a single nanoantenna.
关键词： phase-matching conditions,terahertz radiation,carbon nanotubes,laser radiation,plasmon waves
更新于2025-09-23 15:19:57
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Silsesquioxane-Polythiophene Hybrid Copolymer as an Efficient Modifier for Single-Walled Carbon Nanotubes
摘要： One silsesquioxane-polythiophene hybrid copolymer, with combined star-like structure and intramolecular heterogeneity, was synthesized and sufficiently characterized via various methods, including FTIR, NMR, and SEC measurements. According to the exploration and characterization results, it was much more efficient at modifying SWNTs than its linear analogs in aqueous solution. The hydrophobic silsesquioxane core and PEDOT chains could locally anchor to the surface of the nanotubes, while the soluble flexible copolymer chains extended into the solution and rigid conjugated chains provided some π-π stacking effect to enhance adhesive force with the conjugated structure of the carbon nanotube, imparting steric stabilization to nanotube dispersion. The noncovalent interaction with SWNTs and solubility in aqueous solution improved the electrochemical characteristics of the modified-SWNT composite and availed for the preparation of a flexible and transparent electroactive film. Accordingly, this kind of silsesquioxane-polythiophene hybrid copolymer will be forwarded to apply to the assembling of flexible optoelectronic devices.
关键词： silsesquioxane-polythiophene hybrid copolymer,single-walled carbon nanotubes,noncovalent modification,electrochemical characteristics,aqueous solution
更新于2025-09-23 15:19:57
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Effect of purification on the electrical properties of transparent conductive films fabricated from single-walled carbon nanotubes
摘要： Transparent conductive films (TCFs) made of single-walled carbon nanotubes (SWCNTs) are usually fabricated using highly pure SWCNTs. Obtaining pure SWCNTs is an important step for harnessing their excellent electrical properties. Herein, we studied the effect of purification of SWCNTs by thermal and acid processes on the electrical properties of TCFs. These purification processes also affected the length and diameter of the SWCNT bundles. The purity of SWCNTs was determined by UV–visible-near-infrared spectroscopy and the metal content by thermogravimetric analysis. TCFs were made by spraying aqueous suspensions of SWCNTs having different purities onto polyethylene terephthalate substrates, and the ratios of dc to optical conductivities of the films were compared. Thermally purified (TP) SWCNT TCFs had a higher ratio than thermally and acid-purified (TAP) ones even though the purity of the TP-SWCNTs was lower than that of the TAP-SWCNTs. The conducting paths of the SWCNT bundle networks in the TP-SWCNT TCFs were well organized, because nanosized graphitic nanoparticles and metal catalysts occupied the spaces between the CNT bundles or networks without hindering the network connections. Although the SWCNT purity affected the conductivity of the SWCNT TCFs, the network property of lower junction resistance with smaller bundle diameter was more influential on film conductivity.
关键词： Transparent conductive films,Film network morphology,Purification,Single-walled carbon nanotubes,Purity evaluation
更新于2025-09-23 15:19:57
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Preparation method and underlying mechanism of MWCNTs/Ti6Al4V nanocomposite powder for selective laser melting additive manufacturing
摘要： The fabrication of high-performance metal matrix nanocomposites is a new development direction in laser additive manufacturing (AM); however, the unique localized line-by-line and layer-by-layer forming process of AM has special requirements on the applicable powder materials for AM. The feedstock powder preparation is an important factor in laser AM, especially the CNTs/metal nanocomposite powder for selective laser melting (SLM) due to the agglomeration of the CNTs. This work focused on the preparation of multi-walled carbon nanotubes/Ti6Al4V (MWCNTs/TC4) nanocomposite powder for laser AM by a planetary ball-milling (PBM). The effect of ball-milling time on the characteristics of nanocomposite powder was studied and the underlying physical mechanism for powder preparation was disclosed. Three nanocomposite powders with milling time of 2 h, 4 h and 16 h were used for SLM processing to determine the optimal nanocomposite powders. The results showed that although the MWCNTs were dispersed uniformly in the matrix powder at increased milling time, severely plastic deformation of nanocomposite powder occurred with loss of its spherical shape. It was concluded that a ball-milling time of 4 h at a speed of 300 rpm was determined to achieve optimal nanocomposite powder for SLM. SLM processing of the nanocomposite powder demonstrated a smooth laser-powder interaction, yielding good metallurgical bonding of scanning tracks with previous tracks and relatively flat surface of samples. This work provided the significant reference to prepare high quality CNTs/metal nanocomposite powder for SLM, which has great potentials to fabricate high-performance metal matrix nanocomposite.
关键词： Planetary ball milling,Selective laser melting,Ti6Al4V (TC4) powder,Multi-walled carbon nanotubes (MWCNTs),Powder characteristics
更新于2025-09-23 15:19:57
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Enhanced photovoltaic performance and stability of perovskite solar cells by interface engineering with poly(4-vinylpyridine) and Cu2ZnSnS4&CNT
摘要： Organic-inorganic perovskite solar cells (PSCs) are emerging candidates for next generation photovoltaic devices. In the last decade, PSCs have depicted a rapid development in device performance, meanwhile, the issue of utilizing low-cost, non-toxic materials with chemical stability as well as long term device stabilities are still lacking. To address these issues, an inexpensive, eco-friendly, and environmentally stable nanostructure of the quaternary chalcogenide Cu2ZnSnS4 (CZTS) as an inorganic hole transport material (HTM) has been investigated. Moreover, simultaneously two strategies has been employed to optimize the photovoltaic parameters. First, an interlayer of poly(4-vinylpyridine) (PVP) has been applied between the perovskite and the hole transport layer (HTL). Second, single-walled carbon nanotubes (CNTs) is incorporated into the CZTS HTL. While, the latter only result in higher short circuit current density (Jsc) from 18.3 to 20 mA cm?2, by using both of the strategies an increase in open circuit voltage (Voc) from 0.98 to 1.05 V as well as Jsc from 18.3 to 20.5 mA cm?2 has been observed. The power conversion efficiency (PCE) of the record device reached to 15.2%, fill factor (FF) increased up to 70% and also demonstrated low hysteresis of 2.3%. The formation of hydrophobic CNT webs among the sphere-like CZTS nanostructures and the presence of the PVP polymeric interlayer results in highly stable devices, which retained more than 98% of the initial PCE at room temperature and 40–45% humidity after 30 days. Thus, our results show that the combination of PVP interlayer and CZTS&CNT HTL offer an opportunity for the scalability of PSCs.
关键词： Cu2ZnSnS4,Inorganic hole transport materials,Stability,Carbon nanotubes,Poly(4-vinylpyridine)
更新于2025-09-23 15:19:57
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Composite Interlayer Consisting of Alcohol-Soluble Polyfluorene and Carbon Nanotubes for Efficient Polymer Solar Cells
摘要： We report the synthesis of composite interlayers using alcohol-soluble polyfluorene (ASP)-wrapped single-walled carbon nanotubes (SWNTs) and their application as electron transport layers for efficient organic solar cells. The ASP enables the individual dispersion of SWNTs in solution. The ASP-wrapped SWNT solutions are stable for 54 days without any aggregation or precipitation, indicating their very high dispersion stability. Using the ASP-wrapped SWNTs as a cathode interlayer on zinc oxide nanoparticles (ZnO NPs), a power conversion efficiency of 9.45% is obtained in PTB7-th:PC71BM-based organic solar cells, which is mainly attributed to the improvement in the short circuit current. Performance enhancements of 18% and 17% are achieved compared to those of pure ZnO NPs and ASP on ZnO NPs, respectively. In addition, the composite interlayer is applied to non-fullerene-based photovoltaics with PM6:Y6, resulting in the PCE up to 14.37%. The type of SWNT (e.g., in terms of diameter range and length) is not critical to the improvement in the charge-transport properties. A low density of SWNTs in the film (~1 SWNTs/μm2 for ASP-wrapped SWNTs) has a significant influence on the charge transport in solar cells. The improvement in the performance of the solar cell is attributed to the increased internal quantum efficiency, balanced mobility between electrons and holes, and minimized charge recombination.
关键词： interfacial layers,alcohol-soluble polyfluorene,interlayers,organic solar cells,conjugated polyelectrolytes,Carbon nanotubes,electron transport layers,composites
更新于2025-09-23 15:19:57
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Liquid-Crystal Phase Optimization Using the Alignment Relay Technique for the Deposition of Single-Walled Carbon Nanotubes
摘要： The alignment and sorting of carbon nanotubes constitutes a challenging and industrially significant field of research. We have recently created a technique to simultaneously align and sort single-walled carbon nanotubes on a surface through the use of a specially designed organic thin film. This alignment relay technique can be intelligently altered to judiciously target key parameters of nanotube deposition including density, alignment, and length. Here, we demonstrate that by simply altering the nature of the liquid crystal used the average length of the nanotubes can be decreased by half while increasing the density 3-fold, with minimal impact on the diameter sorting.
关键词： liquid crystals,molecular chemistry,iptycenes,surface chemistry,carbon nanotubes
更新于2025-09-23 15:19:57