碳纳米管/液晶复合材料的研究进展

当今各种纳米材料在液晶显示和非显示应用方面已显示出非凡潜力。其中,碳纳米管与液晶分子同具各向异性几何外形,更容易分散到液晶中,稳定性更强。本文简要综述了近年来碳纳米管/液晶复合材料的研究进展,首先介绍了碳纳米管与液晶材料的基础概念与分类,讲述了将碳纳米管分散到液晶中常用的3种方法,讨论了碳纳米管对液晶材料相变温度、光学性能、电导率、介电性质与力学性能等物理性质的影响,最后介绍了碳纳米管/液晶复合材料在致动器、传感器、手写板、高强度材料等领域的应用。对碳纳米管/液晶复合材料制备、性能与应用研究的认识,将有助于探讨碳纳米管与液晶分子间相互作用导致改善液晶热、介电、电光、力学等物理性质的确切机制,为未来相关应用的实现奠定了基础。     

碳纳米管/液晶弹性体复合材料的力学性能

近年来,碳纳米管/液晶弹性体复合材料凭借其稳定高效的光热性能,成为目前刺激-响应液晶弹性体领域的一个重要研究方向,但目前研究者大多重点关注其光响应行为及使用场景,并未系统研究碳纳米管对液晶弹性体材料力学性能的影响。本文通过物理掺杂的方法制备了不同质量分数的碳纳米管/液晶弹性体复合材料,并利用傅里叶红外光谱、差示扫描量热仪、广角X射线衍射仪、动态热机械分析仪等对制备的复合材料进行热学、液晶性质和力学性能的表征及分析。实验结果表明,碳纳米管的掺杂量对复合材料的力学性能有明显影响,其中掺杂质量分数8%的单壁碳纳米管的液晶弹性体复合材料的力学性能最为优异。在30℃时,断裂强度为5.62 MPa,断裂伸长率为182%;在85℃(清亮点温度之上)时,其断裂强度为1.62 MPa,断裂伸长率为89%。相对于纯液晶弹性体薄膜材料而言,质量分数8%碳纳米管的液晶弹性体复合材料的断裂强度接近纯液晶弹性体薄膜的3倍,且可以实现最大收缩率为45%的可逆伸缩形变,在人造肌肉、软体机器人等智能材料领域表现出有良好的应用前景。     

一种PMMA表面改性的热压键合方法研究

介绍了一种基于表面改性技术的PMMA热压键合新方法。PMMA表面首先用其单体MMA进行改性，然后在真空热压设备中热压键合。主要的键合参数如下：键合压力0．5MPa～2．5MPa，温度88℃～100℃，时间180s。通过拉力法测量了键合强度，其最大值可达到0．15MPa。实验结果表明，与常规的热压键合方法相比，该方法可有效地降低键合温度，减少键合时间，提高键合强度，从而可减少对PMMA基片上微细图形结构的破坏。使用聚合物的单体（MMA）对PMMA进行改性，可避免对微管道产生化学污染，有利于集成毛细管电泳的生化分析。利用品红和氢氧化钠混合溶液对键合后的微流体芯片进行密封性测试，结果表明，封装后的微流体芯片没有出现泄漏的情况。     

BaTiO3表面改性对其环氧树脂复合材料性能的影响

采用硅烷偶联剂KH550对BaTiO3粉末进行了表面改性,以提高BaTiO3-环氧树脂复合材料的性能.研究了钛酸钡颗粒的表面状态、复合材料的微观形貌和介电性能以及复合材料与铜箔问的结合力,探讨了表面改性影响复合材料电学和力学性能的作用机理.结果表明:BaTiO3的表面改性有利于BaTiO3在环氧树脂基体中的分散,提高了...     

新型导电高聚物对神经元修补元件的表面改性

利用一种新型的导电聚合物——聚3,4-二氧化乙烷噻吩(PEDOT)的衍生物PEDTM,成功地在用微加工技术制作的神经元修补元件的电极上制得了导电涂层。该导电聚合物既克服了聚吡咯由于α—β(β?键接而产生的缺陷, 又克服了EDOT在水中溶解度小,无法在生物分子的掺杂下电化学合成PEDOT/生物分子导电涂层的缺陷。SEM和AFM照片表明PEDTM/PSS导电涂层具有粗糙的表面形貌,表面积增加,其阻抗也比未涂层前降低很多,在1 kHz处其阻抗值降低了两个数量级。研究结果表明,PEDTM/生物分子导电涂层的阻抗比聚吡咯/生物分子涂层降低得更多。     

碳纳米管分散形态的电镜研究

未经处理的碳纳米管常呈现团聚形态。然而，团聚形态对进一步深入研究碳纳米管的性能与应用造成了很大的局限．所以，碳纳米管的有效分散至关重要。现在国内虽已对碳纳米管的分散进行了一定的探索，但却未能对分散务件进行定量标定。本文采取超声波振荡的方法进行分散，并细致、深入地探讨了不同分散务件对碳纳米管分散形态的影响，从而说明选用适当的碳纳米管原料、延长超声振荡时间以及降低悬浮液浓度都将有利于碳纳米管的充分分散。     

离子注入金属材料表面改性

本文着重叙述了最近以来离子注入金属材料改性新的进展。离子注入金属的研究,其研究对象品种繁多,需要高注量,且样品形状复杂,因此离子注入金属中的物理问题比半导体离子注入更加复杂。包括各种离子注入多种金属所出现的溅射腐蚀、倾斜注入、特球形状注入、离子浓度分布、注入条件与金属相变的关系以及离子注入提高耐磨损机理等诸多难题。离子注入金属材料改性研究近年来极为活跃,已发表了不少评论文章。希望这篇评论能对从事离子束材料改性工作的人员有所帮助。     

碳纳米管金属复合材料的合成及其吸波性能

通过乙炔催化裂解制得碳纳米管,采用浓硫酸和双氧水的混合溶液对碳纳米管进行表面羟基化修饰,利用化学镀使Pd、Co以及FePt金属纳米粒子成功地吸附在碳管表面,结果发现碳纳米管及其复合物均为介电损耗型介质,Co-碳纳米管复合物相比纯碳纳米管在高频区域有较强的宽范围吸收。     

天然橡胶/改性粘土复合材料结构与性能研究

为提高非碳黑填料对橡胶等高分子材料的补强作用，人们研究了多种的填料改性方法，包括偶联剂、分散剂及其它化学、物理改性［１—２］。本工作采用还原剂、强酸、热处理等对二种不同粘土进行化学改性并进行结构研究，再制备粘土胶复合材料，测定其硫化胶的物理力学性能和...     

填充碳纳米管/石墨的有机导电膜

介绍一种填充碳纳米管 /石墨的有机导电膜的制备及导电膜的组成与处理条件对其导电性能影响的研究 .实验发现 ,当碳纳米管 /石墨的配比为 1 /7— 1 /4 ,有机聚合物 /导电填料的配比为 2 7.6/72 .4— 32 .4/67.6时 ,该有机导电膜具有最佳的电性能和力学性能 ,且在一定条件下呈现负的温度系数 .采用多层结构模型推导出导电膜的电流密度表达式 ,其理论值与实验值相符合 .     

Additive‐Free Dispersion of Single‐Walled Carbon Nanotubes and Its Application for Transparent Conductive Films

A good dispersion of single‐walled carbon nanotubes (SWCNTs) in liquid media is a prerequisite to fulfill many of their applications. This contribution reports an efficient approach to additive‐free dispersion of SWCNTs with the aid of functionalized carbonaceous byproducts (CBs, e.g., amorphous carbon, carbon nanoparticles, and carbonaceous fragments) in SWCNT products. SWCNT bundles are treated by oleum intercalation and nitric acid oxidation in sequence, which leads to the selective functionalization of the CBs while the structure and properties of the SWCNTs are well preserved. These functionalized CBs can improve the subsequent dispersion of SWCNTs and the majority of SWCNTs in the suspension are present in small bundles or individually. Moreover, SWCNT transparent conductive films (TCFs) are fabricated by using these suspensions. The SWCNT TCFs obtained can achieve a low sheet resistance of 76 and 133 Ω sq^?1, with optical transmittance of 82% and 90% at 550 nm, respectively.     

碳纳米管的制备、修饰及其应用

简要介绍了碳纳米管的制备及其纯化技术，以及近年来碳纳米管修饰、管内填充方面的研究，并概述了碳纳米管在复合材料、发光材料、纳米器件方面的应用及其在固体基片上的定向组装。     

纳米金修饰碳纳米管阵列结构的表面增强拉曼散射

研究了纳米金粒子修饰碳纳米管阵列结构的表面增强拉曼散射性能.通过FDTD理论模拟仿真了不同粒径纳米金颗粒的场强分布;并采用化学还原的方法制备出直径分别为20、40和60 nm三种不同粒径的金颗粒,然后将纳米金粒子修饰到有序定向的碳纳米管阵列表面,并将该结构作为表面增强拉曼基底.FDTD软件仿真结果表明,60 nm粒径的纳米金颗粒周围场强分布最强,是入射场场强的15倍.同时将罗丹明6G溶液用于测试几组不同尺寸的金颗粒对拉曼散射光强的影响,发现60 nm金颗粒对R6G拉曼信号增强最大.FDTD理论模拟仿真和罗丹明6G溶液实验测试结果表明:金颗粒尺寸在20～60 nm内,颗粒尺寸越大,拉曼散射光的光强越大.     

Towards Efficient Dispersion of Carbon Nanotubes in Thermotropic Liquid Crystals

Motivated by numerous recent reports indicating attractive properties of composite materials of carbon nanotubes (CNTs) and liquid crystals (LCs) and a lack of research aimed at optimizing such composites, the process of dispersing CNTs in thermotropic LCs is systematically studied. LC hosts can perform comparably or even better than the best known organic solvents for CNTs such as N‐methyl pyrrolidone (NMP), provided that the dispersion process and choice of LC material are optimized. The chemical structure of the molecules in the LC is very important; variations in core as well as in terminal alkyl chain influence the result. Several observations moreover indicate that the anisotropic nematic phase, aligning the nanotubes in the matrix, per se stabilizes the dispersion compared to a host that is isotropic and thus yields random tube orientation. The chemical and physical phenomena governing the preparation of the dispersion and its stability are identified, taking into account enthalpic, entropic, as well as kinetic factors. This allows a guideline on how to best design and prepare CNT–LC composites to be sketched, following which tailored development of new LCs may take the advanced functional material that CNT–LC composites comprise to the stage of commercial application.     

Tailored Assembly of Carbon Nanotubes and Graphene

This Feature Article reviews recent progress in the tailored assembly of carbon nanotubes and graphene into three‐dimensional architectures with particular emphasis on our own research employing self‐assembly principles. Carbon nanotubes and graphene can be assembled into macroporous films, hollow spherical capsules, or hollow nanotubes, via directed assembly from solvent dispersion. This approach is cost‐effective and beneficial for large‐scale assembly, but pre‐requests stable dispersion in a solvent medium. Directed growth from a nanopatterned catalyst array is another promising approach, which enables the control of morphology and properties of graphitic materials as well as their assembly. In addition, the aforementioned two approaches can be synergistically integrated to generate a carbon hybrid assembly consisting of vertical carbon nanotubes grown on flexible graphene films. Tailored assembly relying on scalable self‐assembly principles offer viable routes that are scalable for mass production towards the ultimate utilization of graphitic carbon materials in nanoelectronics, displays, sensors, energy storage/conversion devices, and so on, including future flexible devices.     

纳米碳管及相关材料的电性能

碳管是Ｃ原子按一定的排列方式形成一封闭的结构，构成有别于金刚石和石墨的Ｃ的第三种分子形式。１９９１年日本发现了碳管的一种形式——纳米碳管。这类材料具有特殊的力学、化学、磁学、电学等性能。笔者综述纳米碳管及相关材料的电学性能及应用前景，指出这类材料近期有望在复合材料中得到应用，而运用到电子工业尚需较长的时间     

掺杂单壁碳纳米管的电流特性

依据Boltzmann方程及单壁碳纳米管(SWNTs)能量色散关系,对单个掺杂SWNTs(金属型和半导体型)所加偏压、掺杂浓度及管口直径影响输运电流的性质进行数值计算.分析表明,掺杂SWNs中的电流随偏压变化呈现跃变结构;管口直径、掺杂后Fermi能级附近的态密度以及各通道输运电子的能力直接决定电流的特性,如电流强度、跃变间隔及跃变幅度;同时电流的特性也与温度有关.     

Composites of Polyacrylonitrile and Multiwalled Carbon Nanotubes Prepared by Gelation/Crystallization from Solution

Composite films of polyacrylonitrile (PAN) and multiwalled carbon nanotubes (MWNTs) have been prepared by gelation/crystallization from solution. The contents of MWNTs were 5–10 wt.‐%, measured against PAN. The electrical and mechanical properties have been studied in comparison with those of the homopolymer PAN films prepared from the same method. Furthermore, stabilization and the carbonization have been carried out by using the drawn PAN–MWNTs as a new precursor to prepare carbon films with a cross‐sectional area much larger than that of a commercial carbon fiber (> 3000 times). The MWNTs within the PAN matrix promote the formation of a condensed aromatic ladder structure during the stabilization process and play an important role in preparing PAN‐based carbon material with high carbon quality and high mechanical properties. When the stabilized composites with 10 wt.‐% MWNTs are carbonized at 1000 °C, the Young's modulus reaches 37.5 GPa, and the electrical conductivity reaches 10² S cm^–1. The carbonized PAN homopolymer does not form an adequately robust bulk film for the mechanical properties to be measured.     

The Influence of Surface Chemistry and Pore Size on the Adsorption of Proteins on Nanostructured Carbon Materials

Carbon films are synthesized by templating of anodic aluminum oxide films. These carbon materials exhibit nanochannels with controlled diameter and length. Selected chemical treatments are done to tailor the surface chemistry. The adsorption capacities of bovine serum albumin and cytochrome c are measured by temperature‐programmed desorption with mass spectrometry (TPD‐MS) analysis and with conventional biological assays. The first method allows quantification of the proteins that exhibit strong interactions with the surface, while the second one is used to obtain the total adsorption capacity. Moreover, the TPD‐MS profiles, which are related to the structural modifications of the proteins during the adsorption, show that strong interactions take place with hydrophobic surfaces. When oxygenated functions are present, the adsorption capacity increases and the nature of the interactions is modified. The ratio of irreversible to reversible adsorption is significantly different for the two proteins, and is slightly related to the surface chemistry. The influence of nanochannel size is studied: below 50 nm, the coverage ratio shows that access to the porosity is limited by diffusion in the channel and by pore plugging, in agreement with the strong interactions of proteins with the carbon surface.