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碳纳米管的纯化及其在聚乙烯醇中的分散 总被引:3,自引:0,他引:3
采用硫酸和硝酸混合酸对多壁碳纳米管(MWNTs)进行纯化,利用红外光谱(IR)、X射线衍射(XRD)对MWNTs进行了表征;聚乙烯醇/乙醇(V/V=1:1)溶液分散MWNTs,循环伏安法(CV)测试了碳纳米管/聚乙烯醇膜修饰电极的电化学性能.实验结果表明,混酸处理可以提高碳纳米管的纯度及石墨化程度,并可以在碳纳米管上引入羧基功能团;碳纳米管可以均匀地分散在聚乙烯醇/乙醇溶液中并形成稳定的悬浮液,同时碳纳米管/聚乙烯醇膜修饰电极对苯二酚具有明显电化学催化活性. 相似文献
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柔性超级电容器因其加工方式灵活,具有高的能量密度和可剪裁可弯曲的特性,近年来受到广泛的关注.碳纳米管阵列凭借其自身良好的电化学性能、高效的电荷转移率和良好的循环寿命被视为理想的能量储存材料.然而原始碳纳米管阵列密度较小,且因管间较弱的相互作用力使得其在加工和转移过程中容易倒塌散落,从而限制了碳纳米管阵列直接用于组装柔性电子器件.本文应用无水乙醇对阵列进行收缩处理,在保持阵列高度取向优势的前提下大大增加了阵列的密度和机械强度,同时使用生物相容性好的聚乙烯醇(PVA)导电凝胶包埋碳纳米管阵列来制备柔性固态超级电容器件.PVA包埋的阵列复合体在折叠、弯曲过程中既能保持良好的机械稳定性和柔性,又能保持碳纳米管的高度取向性.使用原位电氧化对碳纳米管阵列外壁进行简单的电化学修饰,可以进一步提高该复合器件的性能.该方法为未来研发可穿戴电子器件以及可植入医学器件提供了新思路. 相似文献
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拾取指定长度的半导体性碳纳米管对大规模制造碳纳米管场效应管具有重要意义.本文提出了一种利用原子力显微镜探针和钨针对碳纳米管进行可控长度拾取的方法并进行了碳纳米管导电性分析.在扫描电子显微镜下搭建微纳操作系统,针对切割操作过程中原子力显微镜探针、钨针和碳纳米管的接触情况进行了力学建模和拾取长度误差分析.建立了单根金属性碳纳米管、单根半导体性碳纳米管及碳纳米管束与钨针接触的电路模型,推导了接入不同性质碳纳米管后电路的电流电压特性方程.使用原子力显微镜探针对碳纳米管的空间位姿进行调整,控制钨针对碳纳米管上目标位置进行通电切割,同时获取切割电路中的电流电压数据.实验结果表明,本文提出的方法能够有效控制所拾取碳纳米管的长度,增加碳纳米管与原子力显微镜探针的水平接触长度能够减小碳纳米管形变导致的拾取长度误差,建立的电流电压特性方程能够用于分析碳纳米管的导电性. 相似文献
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将经典金属自由电子气模型应用于金属型碳纳米管, 基于光学天线有效波长理论, 得出了金属型碳纳米管光学天线响应的有效波长与碳纳米管介电特性之间的普适关系. 在对碳纳米管介电特性进行第一性原理计算的基础上, 以金属型4 Å碳纳米管为例, 进一步研究了金属型碳纳米管光学天线响应的有效波长与入射波长之间的关系, 以及金属型碳纳米管光学偶极子天线的谐振特性. 通过将已有传统金属光学天线和碳纳米管天线有效波长的研究结果进行对比, 验证了本文理论的正确性. 结果表明, 碳纳米管光学天线响应的有效波长与入射波长呈近似线性关系, 与传统金属材料构成的同直径光学天线相比, 碳纳米管天线显示出了更强的波长压缩能力, 并且在可见光到红外波段内易于发生谐振. 该研究方法可为碳纳米管光学天线研究提供新的思路. 相似文献
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以二茂铁、二甲苯为前驱体,石英为衬底,在850 oC的管式炉内采用化学气相沉积法制备出了定向碳纳米管阵列. 高分辨透射电子显微镜和拉曼光谱的结果表明:碳纳米管阵列具有良好的定向性和多壁管状结构,石墨化程度高,并且只在表面存在少量单壁碳纳米管.定向多壁碳纳米管阵列的生长模式为“底部”生长模式,即在生长的初期,当催化剂颗粒较小时,析出的碳原子生成了单壁碳纳米管或与其性质类似的多壁碳纳米管(一般层数小于5层);催化剂颗粒逐渐长大后,大量的碳原子析出后生成了普通的多壁碳纳米管,从而形成了单壁碳纳米管只存在于碳纳米管阵列膜表面和多层碳纳米管膜表面与界面的现象. 相似文献
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O. A. Nikolaeva V. I. Kodolov L. G. Makarova A. Yu. Volkov E. G. Volkova 《Physics of the Solid State》2002,44(3):525-526
Metal-containing carbon nanostructures are prepared by heating poly(vinyl alcohol) in mineral media with a lamellar structure at a temperature below 300°C. It is demonstrated that three possible types of nanostructures can be formed, namely, multilayer carbon nanotubes, spherical carbon nanoparticles, and finely crystalline carbon structures. According to the data of transmission electron microscopy, the nanotube size falls in the range from 50 to 300 nm and the nanotubes themselves have a stranded structure. 相似文献
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Dispersion of carbon nanotubes in a polymer matrix is one of the most critical issues in carbon nanotube/polymer composites. In this paper we discuss the considerable improvement in the dispersion of multiwalled carbon nanotubes (MWNTs) in poly(vinyl alcohol) (PVA) matrix that was attained through gum arabic treatment. The mechanical properties of these MWNT/PVA composites show that only 2 wt% nanotube loading increases the tensile modulus by more than 130%. 相似文献
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Superbase‐catalyzed domino 3H‐pyrroles synthesis from ketoximes and acetylene: DFT study vs experiment 下载免费PDF全文
Elimination of vinyl alcohol from 5‐vinyloxypyrrolines in the presence of superbases (final step of domino 3H‐pyrroles synthesis from ketoximes and acetylene) is studied computationally at different levels of theory in DMSO solution (PCM). The sequences of transformations starting from nucleophilic addition of hydroxide ion to carbon‐carbon or carbon‐nitrogen double bonds are proposed as possible mechanisms. Unusual reactivity of 2,5‐dimethylphenyl substituted 5‐vinyloxypyrroline is explained within these mechanisms. 相似文献
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Paolo Ciambelli Maria Sarno Giuliana Gorrasi Diana Sannino Mariarosaria Tortora 《Journal of Macromolecular Science: Physics》2013,52(5):779-795
Nanocomposite materials were prepared by incorporating multiwall carbon nanotubes (MWNTs), obtained by acetylene catalytic chemical vapor deposition (CCVD) on Co/Fe‐modified MgO, within poly(vinyl alcohol) (PVA). Before incorporation, nanotubes were oxidized to obtain better compatibilization with the polymer. It has been found that the addition of COOH‐functionalized and purified MWNTs improves the mechanical response, increases the glass transition temperature, and delays the thermal oxidation of PVA. Furthermore, the PVA crystallinity seems to be enhanced by the presence of nanotubes. 相似文献
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《Composite Interfaces》2013,20(8-9):757-768
Single wall carbon nanotubes (SWNT) are functionalized with poly(vinyl alcohol) (PVA). The functionalized nanotubes are homogeneously dispersed in a PVA solution. Nanocomposite films with low SWNT content (0.1 to 1%) are produced by the wet-casting method. X-ray diffraction shows that the PVA crystallinity was not affected by the presence of the SWNT. The improvement in tensile modulus and strength at such low reinforcement loadings is indicative of good interfacial bonding between the functionalized nanotubes and the polymer matrix. 相似文献
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The current work reports the effect of multi walled carbon nanotubes and single walled carbon nanotubes dispersion on morphological, structural and thermal degradation of electrospun poly(vinyl alcohol) (PVA)/carbon nanotubes (CNTs) dispersed in sodium dodecyl sulfate (SDS) (PVA/CNTs–SDS) composites nanofibers. (PVA/CNTs–SDS) nanocomposites fibers were elaborated using the traditional electrospinning process to disperse and align CNTs into the fibers, especially for low CNTs loading fraction: 0.3 and 0.7 wt%. The morphology of the electrospun fibers was studied using the scanning electronic microscopy. The average diameter of the fibers changes significantly after the incorporation of the CNTs in the PVA. Furthermore, Fourier transform infrared spectroscopy elucidated the effect of CNTs on the crystallization of the PVA which was confirmed by X-ray diffraction analysis. Thermogravimetric analysis showed that the thermal stability of the composite fibers depends on the loading fraction and on the type of carbon nanotubes. 相似文献
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Jelena Cveticanin Aleksandra Krkljes Zorica Kacarevic-Popovic Miodrag Mitric Zlatko Rakocevic Djordje Trpkov Olivera Neskovic 《Applied Surface Science》2010,256(23):7048-94
In this paper, an advanced method of one-step functionalization of single and multi walled carbon nanotubes (SWCNTs and MWCNTs) using γ-irradiation was described. Two synthesis procedures, related with different reduction species, were employed. For the first time, poly(vinyl alcohol) PVA is successfully utilized as a source to reduce silver (Ag) metal ions without having any additional reducing agents to obtain Ag nanoparticles on CNTs. The decoration of carbon nanotubes with Ag nanoparticles takes place through anchoring of (PVA) on nanotube's surface. Optical properties of as-prepared samples and mechanism responsible for the functionalization of carbon nanotubes were investigated using UV-vis and FTIR spectroscopy, respectively. Decorated carbon nanotubes were visualized using microscopic techniques: transmission electron microscopy and scanning tunneling microscopy. Also, the presence of Ag on the nanotubes was confirmed using energy dispersive X-ray spectroscopy. This simple and effective method of making a carbon nanotube type of composites is of interest not only for an application in various areas of technology and biology, but for investigation of the potential of radiation technology for nanoengineering of materials. 相似文献
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The crystallization of poly(vinyl alcohol), derived from its aqueous solution was carried out under a steady-state flow. The effect of the rate of stirring on the crystallization and details of several phenomena observed in stirred solutions during crystallization are presented. Moreover, the structure of crystallized poly(vinyl alcohol) was studied with use of an electron microscope. Evidence is presented for a crystal morphology that includes smooth fibrils and the absence of lamellar overgrowth, i.e., no shish kebabs. 相似文献
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Yawen Huang Jianwei Fu Xiaobin Huang Xiaozhen Tang 《Journal of Macromolecular Science: Physics》2013,52(5):941-954
A new type of cross-linker, based on cyclotriphosphazene with six aldehyde groups, was used for the cross-linking of poly(vinyl alcohol) membranes. FTIR-ATR analysis indicated that cyclophosphazene reacted with poly(vinyl alcohol) by forming C–O–C bonds. TGA and DTG analysis showed that cross-linking improved the thermal stability. The swelling degree and pervaporation properties of cross-linked PVA membranes were also characterized. With increasing cross-linker concentration, swelling degrees and flux decrease while separation factors increase. Compared with PVA membranes cross-linked by glutaraldehyde, PVA membranes cross-linked by cyclophosphazene exhibited better selectivity and permeation rate. 相似文献
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Tensile tests were carried out on free-standing composite films of poly(vinyl alcohol) (PVA) and multiwall carbon nanotubes (MWNTs) for different loading levels. Results show that overall mechanical properties of the composite were greatly improved as compared to the neat PVA film. For PVA-based materials at significant high loading level such as 9.1 wt.% MWNTs, considerable increases in Young's modulus, tensile strength and toughness by factors of 4.5, 2.7 and 4.1, respectively, were achieved. Raman, SEM, TEM, and DSC techniques were used to evaluate the PVA/MWNTs composite system. Strong acid-modification of the pristine MWNTs and the subsequent ultrasonication processing allowed good distribution of the nanotubes in the matrix. SEM together with DSC result shows apparent good wetting of the nanotubes by the PVA matrix, which are supportive of good interfacial bonding between the modified carbon nanotubes and the hosting polymer matrix. 相似文献