多壁碳纳米管与溴的相互作用及导电机理

通过溴蒸气的吸附, 提高多壁碳纳米管(MWNT)的本征导电性能, 加溴多壁碳纳米管的电导率提高了3倍. X光电子能谱、近红外光谱、紫外光谱、拉曼光谱表明多壁碳纳米管与溴之间存在共轭作用, 这种作用导致多壁碳纳米管上的π电子向溴偏移, 产生空穴载流子. 利用半导体能带图, 提出加溴多壁碳纳米管微观体系模型来研究溴对多壁碳纳米管的作用及导电机理.     

多壁碳纳米管/溴/聚苯乙炔三元复合材料导电性能的研究

通过机械共混和溶液共混制备了多壁碳纳米管(MWNTs)/溴/聚苯乙炔(PPA)三元复合材料, 复合材料表现出良好的导电性能, 电导率为10 S/m, 达到掺溴MWNTs的导电水平. 通过固体紫外光谱、XPS和SEM分析了复合材料中MWNTs、溴与PPA三者之间的相互作用, 研究了独立导电单元的形成, 以及导电单元对电导率提高所起的作用. 结果表明, 当MWNTs含量较低时, MWNTs和PPA之间的溴转移导致复合材料电导率降低; MWNTs含量较高时, 独立导电单元的数目增多, 复合材料的电导率随之大幅提高.     

多壁碳纳米管/溴/聚苯乙炔三元共混物导电性能的研究

通过机械共混和溶液共混制备了多壁碳纳米管(MWNTs)/溴/聚苯乙炔(PPA)三元复合材料,复合材料表现出良好的导电性能,电导率为10S/m,达到掺溴MWNTs的导电水平.通过固体紫外光谱、XPS和SEM分析了复合材料中MWNTs、溴与PPA三者之间的相互作用,研究了独立导电单元的形成,以及导电单元对电导率提高所起的作用.结果表明,当MWNTs含量较低时,MWNTs和PPA之间的溴转移导致复合材料电导率降低;MWNTs含量较高时,独立导电单元的数目增多,复合材料的电导率随之大幅提高.     

氨基卟啉共价化学修饰多壁碳纳米管

合成了5-(4-氨基)苯基-10,15,20-三苯基卟啉及其铜配合物, 通过化学键将氨基卟啉与活化的多壁碳纳米管(MWNT)发生酰胺化反应, 从而得到卟啉有机共价化学修饰的多壁碳纳米管的复合物. 通过红外光谱对产物的化学结构进行了表征, 证实了复合物体系中酰胺反应的发生. 紫外可见光吸收光谱和荧光光谱分析确定了卟啉与多壁碳纳米管间存在强烈的电子效应. 通过透射电镜(TEM)观察了产物的形貌特征, 发现碳纳米管壁上连接上了氨基卟啉小分子, 进一步证实了酰胺化反应的发生.     

改性多壁碳纳米管/聚乳酸复合材料的研究

制备了改性多壁碳纳米管/聚乳酸复合材料,研究了改性多壁碳纳米管对聚乳酸的增强作用.通过拉曼光谱分析、热重分析证实了多壁碳纳米管酸化酯化反应的发生.通过溶液法制备了聚乳酸/改性多壁碳纳米管复合物.考察了聚乳酸和改性多壁碳纳米管复合体系的相容性.扫描电镜分析结果说明了聚乳酸和改性多壁碳纳米管复合物相容性的变化.随着改性多壁碳纳米管在复合物中含量的增加,体系的分散效果也越好,相容性也有提高.实验结果表明,在聚乳酸材料中添加改性碳纳米管材料到一定值对,可以提高材料的力学性能,且当改性碳纳米管添加量达到1.5％的时候材料力学性能达到了一个最大值,拉伸强度可达120.4MPa.     

水溶性羟基化单壁碳纳米管与人血清白蛋白之间的相互作用研究

利用荧光光谱、UV吸收光谱、同步荧光光谱和透射电子显微镜等技术较为系统地研究了水溶性羟基化单壁碳纳米管与人血清白蛋白(HSA)的相互作用. 实验发现, 这种羟基化单壁碳纳米管可以明显猝灭HSA的内源荧光, 且猝灭效应随碳纳米管浓度增大而增强. 同时, HSA对水溶性羟基化单壁碳纳米管起到一定的分散和稳定作用. 同步荧光光谱表明, 二者之间的相互作用可导致HSA的构象发生变化, HSA的色氨酸残基荧光信号发生2 nm的红移, 表明色氨酸残基周围微环境的极性降低.     

氯掺杂提高多壁碳纳米管的电导率

通过氯气吸附, 制备了掺氯多壁碳纳米管(Cl₂-MWNTs)复合材料, 在低温、高温和紫外光照射条件下掺氯, 紫外光照射下掺氯制备的复合材料电导率最高, 和未掺氯MWNTs相比, 电导率提高到原来的5倍以上. 用热重、红外吸收光谱、紫外-可见吸收光谱、拉曼光谱和X光电子能谱分析研究掺氯碳纳米管中氯和MWNTs间的相互作用, 结果表明: 掺氯后MWNTs中π电子向氯转移, 氯与MWNTs形成共轭体系, π电子的离域性增强, 提高了复合材料的电导率.     

MWNTs/HDPE复合体系在太赫兹波段的光电性质

利用太赫兹时域光谱技术和电导测量研究了多壁碳纳米管/高密度聚乙烯(MWNTs/HDPE)复合体系的光电性质. 直流电导率结果表明, 复合体系的逾渗阈值在5%左右; 交流电导率则随频率的变化出现一个拐点, 拐点的位置与颗粒浓度以及导电颗粒的存在状态密切相关. 加入碳纳米管后, 复合体系在太赫兹波段的吸收系数和折射率均有很大的提高. 通过假定在此波段导电颗粒在聚合物中的介电行为类似于偶极子的弛豫, 利用Cole-Cole理论对复合材料的介电性质进行了解释.     

金属卟啉有机共价和非共价修饰多壁碳纳米管

合成了5-(4-羟基苯基)-10,15,20-三苯基卟啉锌配合物, 与活化的多壁碳纳米管(MWNT)发生酯化反应, 从而得到金属卟啉有机共价化学修饰的多壁碳纳米管复合物; 利用金属卟啉环上的π电子与多壁碳纳米管管壁上的π电子通过π-π堆积效应, 得到金属卟啉有机非共价修饰的多壁碳纳米管复合物. 通过透射电镜(TEM)考察了金属卟啉-多壁碳纳米管复合物的形貌特征; 通过红外光谱对产物的化学结构进行了表征; 通过紫外光谱、荧光光谱和热失重分析(TGA)对比分析了两类复合物, 发现非共价修饰的金属卟啉-碳纳米管复合物的荧光淬灭率更高, 非共价修饰的金属卟啉-碳纳米管复合物中卟啉的含量比较高.     

超声分散对单壁碳纳米管分离的影响

利用凝胶柱色谱技术, 研究者们通过两步或多步淋洗的方法实现了不同导电属性或电子结构单壁碳纳米管(SWCNTs)的分离, 并提出其分离机制主要是由不同导电属性和电子结构的SWCNTs 与凝胶填料之间作用力的差异所导致的. 基于凝胶柱色谱分离技术, 本文重点考察了超声时间对单壁碳纳米管单分散以及金属型/半导体型SWCNTs 分离的影响. 在一定的低超声功率下, 适当增加超声时间有利于SWCNTs 在十二烷基硫酸钠(SDS)溶液中的单分散. 紫外-可见-近红外(UV-Vis-NIR)吸收光谱、拉曼(Raman)光谱和荧光(PL)光谱表征结果表明, 2 h的超声条件是获得高纯度的金属型以及不同直径分布的半导体型SWCNTs 的最优条件. 我们认为不同超声时间对SWCNTs 分离的影响主要是改变了SWCNTs 的单分散性和长度, 调制了不同SWCNTs 与凝胶之间作用力的差异, 从而导致了不同SWCNTs分离结果.     

溴蒸气掺杂聚苯乙炔的导电机理

通过溴蒸气的吸附, 聚苯乙炔(PPA)的电导率比吸溴前提高近12个数量级. 采用固体紫外光谱、X光电子能谱研究了溴与PPA之间的p-π共轭效应, 探讨了掺溴PPA的导电机理. 研究表明, PPA掺溴产生了溴负离子和电子转移复合物, 促使导电率提高. 实验证明压力作用的增大有利于增强溴与PPA之间的共轭作用, 温度升高导致掺溴PPA中p-π共轭结构减少, 导致电导率降低.     

Synthesis and characterization of carbon nanotube/polypyrrole core–shell nanocomposites via in situ inverse microemulsion

We demonstrate here a feasible approach to the preparation of multiwalled carbon nanotube (MWNT)/polypyrrole (PPy) core–shell nanowires by in situ inverse microemulsion. Transmission electron microscopy and scanning electron microscopy showed that the carbon nanotubes were uniformly coated with a PPy layer with a thickness of several to several tens of nanometers, depending on the MWNT content. Fourier transform infrared spectra suggested that there was strong interaction between the π‐bonded surface of the carbon nanotubes and the conjugated structure of the PPy shell layer. The thermal stability and electrical conductivity of the MWNT/PPy composites were examined with thermogravimetric analysis and a conventional four‐probe method. In comparison with pure PPy, the decomposition temperature of the MWNT/PPy (1 wt % MWNT) composites increased from 305 to 335 °C, and the electrical conductivity of the MWNT/PPy (1 wt % MWNT) composites increased by 1 order of magnitude. The current–voltage curves of the MWNT/PPy nanocomposites followed Ohm's law, reflecting the metallic character of the MWNT/PPy nanocomposites. The cyclic voltammetry measurements revealed that PPy/MWNT composites showed an enhancement in the specific charge capacity with respect to that of pure PPy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6105–6115, 2005     

Surface Modification of Carbon Nanotube by Poly(ethylene glycol) for the Preparation of Poly(vinyl alcohol) Nanocomposite

Herein, PEGylated multi-walled carbon nanotube (MWNT) was prepared for the successive fabrication of poly(vinyl alcohol) PVA/MWNT nanocomposite film by solution casting. The surface modified MWNT showed a good colloidal stability in a polar solvent, i.e., water. Also, the PEGylated MWNT had an improved dispersion stability in aqueous PVA solution. The mixture of PEGylated MWNT and PVA dissolved in water was film casted and the dispersion uniformity and corresponding improvement of electrical conductivity were investigated. The electrical conductivity of PVA/modified MWNT composite film was three-fold higher than that of PVA/pristine MWNT composite film due to the much improved distribution uniformity of modified MWNT in PVA matrix.     

Grafting of polyaniline onto the surface of 4‐aminobenzoyl‐functionalized multiwalled carbon nanotube and its electrochemical properties

Polyaniline (PANi)‐grafted multiwalled carbon nanotube (MWNT) composite is prepared by a two‐step reaction sequence. MWNT is first functionalized with 4‐aminobenzoic acid in polyphosphoric acid/phosphorous pentoxide as a “direct” Friedel‐Crafts acylation reaction medium. The resultant 4‐aminobenzoyl‐functionalized MWNT is then treated with aniline using ammonium persulfate/aqueous hydrochloric acid to promote a chemical oxidative polymerization, leading to PANi‐grafted MWNT composite. The resultant composite is characterized by elemental analysis, Fourier‐transform infrared spectroscopy, wide‐angle X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, UV–vis absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and electrical conductivity measurement. The thermooxidative stability and electrical conductivity of PANi‐grafted MWNT composite are improved compared to those of PANi. Specifically, the electrical conductivity of PANi‐grafted MWNT is improved 10–900 times depending upon the level of doping. The capacitance of the composite is also greatly enhanced. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3103–3112, 2010     

Influence of multiwall carbon nanotubes on morphology and electrical conductivity of PP/ABS blends

Polypropylene (PP) and acrylonitrile‐butadiene‐styrene (ABS) blends with multiwall carbon nanotubes (MWNT) were prepared by melt mixing. PP/ABS blends without MWNT revealed coarse co continuous structures on varying the ABS content from 40 to 70 wt %. Bulk electrical conductivity of the blends showed lower percolation threshold (0.4–0.5 wt %) in the 45/55 co continuous blends whereas the percolation threshold was between 2 and 3 wt % in matrix‐particle dispersed morphology of 80/20 blends. Interestingly, droplet size was observed to decrease with addition of MWNT above percolation threshold in 80/20 blends. Further, the bulk electrical conductivity was found to be dependent on the melt flow index of PP. The non‐polar or weakly polar nature of blends constituents resulted in the temperature independent dielectric constant, dielectric loss, and DC electrical conductivity. Rheological analysis revealed the formation of 3D network‐like structure in 80/20 PP/ABS blends at 3 wt % MWNT. An attempt was made to understand the relationship between rheology, morphology, and electrical conductivity of these blends. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2286–2295, 2008     

Enhanced electrical conductivity in chemically modified carbon nanotube/methylvinyl silicone rubber nanocomposite

Chemically modified multiwalled carbon nanotubes/methlyvinyl silicone rubber (m-MWNT/VMQ) nanocomposites with relatively good dispersion of nanotubes were prepared by treating the surface of MWNT using γ-aminopropyltriethoxy silane (KH550). Significant enhanced electrical conductivity was discovered in the m-MWNT/VMQ nanocomposites. The results could be attributed a strong interaction between m-MWNT and VMQ which was from the chemically modification of the surface for MWNT. The electrical property was also discussed in order to understand the percolation and electrical transport mechanism. The m-MWNT/VMQ nanocomposites with high conductivity in this study are promising application as one of novel functional materials.     

聚3-辛基噻吩/MWNTs复合材料的导电性能研究

采用在氯仿溶液中超声共混, 制备聚3-辛基噻吩(P3OT)和多壁碳纳米管(MWNTs)复合材料. 当MWNTs掺杂量为3%时复合材料的电导率为1.43 S•m－1, 达到纯MWNTs的电导率水平. 用FTIR光谱, TG, UV-Vis光谱, XPS和FESEM进行研究分析, 认为MWNTs的离域电子与P3OT主链上的π电子之间形成π-π共轭, 增加了P3OT主链的有效共轭度, 被掺杂的P3OT具有很高的电导率, 提高了复合材料的导电性能. MWNTs与被掺杂的P3OT组成相对独立的导体单元, 对复合材料的导电网络形成起着主要作用.