单壁碳纳米管短管的制备

分别通过控制CVD生长时间的方法和在混合的硝酸硫酸中超声氧化碳纳米管的化学剪裁法制备了单壁碳纳米管短管.两种方法都能将大多数碳纳米管的长度控制在500 nm以下.拉曼光谱结果表明: 在化学剪裁过程中,单壁碳纳米管部分被破坏产生无定形碳杂质;用控制CVD反应时间得到的单壁碳纳米管短管样品比长时间反应得到的长管样品杂质少,且不存在后处理时碳纳米管的破损问题,其纯度比化学剪裁法得到的产品纯度高.     

通过溴代烷烃和羧基的酯化反应制备烷基改性的多壁碳纳米管

以1,8-二氮-二环[5,4,0]-7-十一烯(1,8-Diazabicyclo[5,4,0]undec-7-ene, DBU)作为催化剂, 通过溴代烷烃和羧基的酯化反应制备了烷基改性的碳纳米管. 分别采用1,6-二溴己烷、溴代正辛烷、溴代正十二烷和溴代正十六烷与硝酸氧化处理的碳纳米管反应, 在碳纳米管表面共价接枝了不同长度的烷基链. 实验结果表明, 烷基改性的碳纳米管能够很好地分散在二氯甲烷、氯仿等有机溶剂中; 并且随着接枝的烷基链碳数的增加, 碳纳米管在有机溶剂中的分散性也越好.     

单壁碳纳米管与卤代烷的亲电加成反应

主要考察了以路易斯酸为催化剂,几种卤代烷烃为反应试剂的单壁碳纳米管侧壁的亲电加成反应,并通过傅立叶红外光谱、热失重分析和拉曼光谱验证了实验所得产物。此反应的目的是在单壁碳纳米管的侧壁连上烷基基团以提高其溶解性和分散性,并可使其更好地与聚烯烃相结合从而提高复合材料的性能,因而具有较高的研究和应用价值。     

在不同激发波长下的单壁碳纳米管的拉曼光谱研究

采用直流电弧法制备单壁碳纳米管样品,用457.5和632.8nm两种不同的激发光分别测得单壁碳纳米管的正常拉曼光谱和共振拉曼光谱.通过理论分析得到了单壁碳纳米管的直径分布,进一步推测了其类型及结构参数;对单壁碳纳米管的正切拉伸模的成分进行了归属.在632.8nm激发波长下得到了IG/ID值随激光功率变化的曲线,认为在2.5mW时,单壁碳纳米管缺陷的结构可能发生了改变.在用457.5nm波长激发的单壁碳纳米管的拉曼光谱中,首次发现了1421cm-1的拉曼谱峰.     

卟啉和酞菁修饰的单壁碳纳米管的合成及光谱性质

利用5-(4-氨基苯基)-10,15,20-三(3,5-二辛氧基苯基)卟啉和2,9,16-三叔丁基-23-氨基锌(Ⅱ)酞菁通过酰胺键连接方式同时对单壁碳纳米管进行共价修饰, 通过红外光谱、拉曼光谱、X射线光电子能谱和透射电镜对所得碳纳米管复合物进行了表征, 证实了其结构. 紫外-可见吸收光谱和荧光光谱分析表明, 光活性分子卟啉和酞菁均与单壁碳纳米管之间存在较强的电子效应. 经卟啉和酞菁共同修饰的单壁碳纳米管复合物比卟啉和酞菁单独修饰的碳纳米管复合物的吸光范围更宽, 而且分散性较好(309 mg/L), 是潜在的光电转换材料.     

聚苯乙烯接枝修饰碳纳米管

本文利用碳纳米管的高比表面性质,使多壁碳纳米管(MWNT)表面吸附大量苯乙烯和过氧化苯甲酰(BPO)后在90℃加热,合成聚苯乙烯(PS)接枝修饰的MWNT。并采用透射电镜(TEM),高倍透射电镜(HR-TEM),场发射扫描电镜(FEW SEM),拉曼光谱(RAMAN),X光电子能谱(XPS),热重(TG)等对功能化后的MWNT进行了分析,证明了确实有大量的PS通过共价键接枝在MWNT表面。     

接枝羧基对单壁碳纳米管弹性性质的影响

采用分子动力学方法对端口接枝不同数量羧基的扶手椅型和锯齿型单壁碳纳米管弹性模量进行了模拟研究. 结果表明, 扶手椅型(5, 5)、(10, 10)管和锯齿型(9, 0)、(18, 0)管在未接枝状态下杨氏模量分别为948、901GPa和804、860 GPa. 在接枝2-8个羧基情况下, 扶手椅型单壁碳纳米管拉伸杨氏模量基本不随接枝数量的增加而发生变化, 而锯齿型单壁碳纳米管则不同, 接枝状态下的弹性模量比未接枝状态小很多, 但随接枝数量的增加又呈略增趋势. 分别从接枝后碳纳米管变形电子密度等值线结构变化、键长变化和系统势能变化规律等方面, 对单壁碳纳米管弹性模量的接枝效应进行了分析.     

非离子型水溶性卟啉功能化单壁碳纳米管的研究

合成了两种非离子型水溶性卟啉分子,并利用它们对单壁碳纳米管(SWNTs)进行了非共价表面修饰。功能化后SWNTs能够在水中均匀分散。紫外-可见光谱、荧光光谱、透射电镜的测试结果均证明非离子型水溶性卟啉分子与SWNTs之间存在强烈的相互作用。其中,含有柔性烷基取代链的卟啉分子因与SWNTs之间存在π-π和疏水双重相互作用,所形成的复合物在水中表现出更好的分散稳定性。这种既具有水溶性又具有生物相容性和良好稳定性的功能化SWNTs,在生物医药领域具有潜在的应用前景。     

端氨基聚氨酯-g-聚丙烯的制备及工艺参数研究

通过反应挤出方法将端氨基聚氨酯(ATPU)接枝到聚丙烯(PP)分子链上,并用红外光谱对AT-PU-g-PP进行了表征。研究了ATPU分子量、配比、螺杆转速等对接枝率的影响,确定了合成高接枝率产物的优化工艺条件。将ATPU-g-PP再与通用PP共混挤出,可得到功能化聚丙烯(FPP)。     

聚苯胺的表面修饰及防腐性能

用八甲基环四硅氧烷(D₄)对聚苯胺(PANI)进行表面修饰, 通过对产物的循环伏安(CV)、 极化曲线(Tafel)以及接枝率的表征分析, 考察了反应温度、 反应时间、 单体用量和pH值对产物的接枝效果、 分散性和腐蚀电位的影响. 同时, 通过循环伏安(CV)、 紫外-可见光谱(UV-Vis)、 红外光谱(FTIR)、 X射线衍射分析(XRD)和热重分析(TGA), 对PANI表面修饰前后的结构和性能进行了比较. 结果表明, 通过D₄对PANI颗粒表面进行修饰, PANI的分散性、 分散稳定性和和防腐能力得到显著提高.     

Capillary electrophoresis of covalently functionalized single‐chirality carbon nanotubes

We demonstrate the separation of chirality‐enriched single‐walled carbon nanotubes (SWCNTs) by degree of surface functionalization using high‐performance CE. Controlled amounts of negatively charged and positively charged functional groups were attached to the sidewall of chirality‐enriched SWCNTs through covalent functionalization using 4‐carboxybenzenediazonium tetrafluoroborate or 4‐diazo‐N,N‐diethylaniline tetrafluoroborate, respectively. Surfactant‐ and pH‐dependent studies confirmed that under conditions that minimized ionic screening effects, separation of these functionalized SWCNTs was strongly dependent on the surface charge density introduced through covalent surface chemistry. For both heterogeneous mixtures and single‐chirality‐enriched samples, covalently functionalized SWCNTs showed substantially increased peak width in electropherogram spectra compared to nonfunctionalized SWCNTs, which can be attributed to a distribution of surface charges along the functionalized nanotubes. Successful separation of functionalized single‐chirality SWCNTs by functional density was confirmed with UV‐Vis‐NIR absorption and Raman scattering spectroscopies of fraction collected samples. These results suggest a high degree of structural heterogeneity in covalently functionalized SWCNTs, even for chirality‐enriched samples, and show the feasibility of applying CE for high‐performance separation of nanomaterials based on differences in surface functional density.     

A New Iodonium Ylide‐Based Three‐Component Reaction Leading to 2‐Spirosubstituted Dihydrofurans under Microwave Irradiation

A new iodonium ylide‐based three‐component reaction for the synthesis of highly functionalized 2‐spirosubstituted dihydrofurans starting from readily available common reactants has been developed under microwave irradiation. The procedure is facile, avoiding time‐consuming and costly syntheses, tedious work‐up and purifications of precursors as well as protection/deprotection of functional groups. This method is very efficient because of short reaction times and easy work‐up and provides an efficient strategy for the construction of the polysubstituted spiro dihydrofuran skeleton.     

Experimental and Computational Investigations of the Properties of Fluorinated Single‐Walled Carbon Nanotubes

Fluorination of single‐walled carbon nanotubes by reaction with elemental fluorine at elevated temperatures provides fluorinated single‐walled carbon nanotubes (F‐SWNT), which have the highest degree of functionalization (up to F/C=1/2) of any derivatized carbon‐nanotube material reported to date. Also, F‐SWNTs have received more scrutiny than any other functionalized carbon nanotubes. This Minireview covers experimental and computational investigations of F‐SWNTs with a focus on the nature and the strength of the C–F linkage.     

Carbon‐Coated and Interfacial‐Functionalized Mixed‐Phase MoxTi1−xO2‐δ Nanotubes as Highly Active and Durable PtRu Catalyst Support for Methanol Electrooxidation

A synchronous carbon‐coating and interfacial‐functionalizing approach is proposed for the fabrication of Mo‐doped Mo_xTi_1?xO_2‐δ nanotubes (C@IF‐MTNTs) under mild hydrothermal reaction with subsequent annealing as advanced catalyst supports for PtRu nanoparticles (NPs) towards methanol electrooxidation. The carbonation of glucose and Mo‐doping takes place simultaneously at the interface of pristine anatase TiO₂ nanotubes (TNTs), generating a unique concentric multilayered one‐dimensional (1D) structure with crystalline an anatase/rutile mixed‐phase TiO₂ core and Mo‐functionalized interface and subsequently a carbon shell. The obtained PtRu/C@IF‐MTNTs catalyst exhibits an over 2 times higher mass activity with comparable durability than that of the unmodified PtRu/C@TNTs catalyst and over 1.7 times higher mass activity with over 20 % higher stability than that of PtRu/C catalyst. Such superior catalytic performance towards methanol electrooxidation is ascribed to the Mo‐functionalized interface, concentric multilayered 1D architecture, and anatase/rutile mixed‐phase core, which facilitates the charge transport through 1D structural support and electronic interaction between C@IF‐MTNTs and ultrafine PtRu NPs. This work reveals the critical application of a 1D interfacial functionalized architecture for advanced energy storage and conversion.     

Synthesis and X‐ray single‐crystal structure study of 5,5′‐bis(silyl)‐functionalized 3,3′‐dibromo‐2,2′‐dithiophenes

A high‐yield synthesis toward 5,5′‐bis(silyl)‐functionalized 3,3′‐dibromo‐2,2′‐dithiophenes with very efficient work‐up procedure is presented. The molecular structures of two silyl functionalized dibromo‐dithiophenes in the solid state have been determined to investigate the structural influences of different functional groups on the degree of π‐conjugation within the dithiophene moieties, as well as their packing properties. The planar alignment of the tert‐butyldimethylsilyl‐functionalized dibromo‐dithiophene shows a significantly higher degree of conjugation of the π‐system with a more favorable molecular packing than the skewed arrangement of the triisopropylsilyl‐substituted species. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of nanotube functionalization on the properties of single‐walled carbon nanotube/polyurethane composites

A commercially available aliphatic thermoplastic polyurethane formulated with a methylene bis(cyclohexyl) diisocyanate hard segment and a poly(tetramethylene oxide) soft segment and chain‐extended with 1,4‐butanediol was dissolved in dimethylformamide and mixed with dispersed single‐walled carbon nanotubes. The properties of composites made with unfunctionalized nanotubes were compared with the properties of composites made with nanotubes functionalized to contain hydroxyl groups. Functionalization almost eliminated the conductivity of the tubes according to the conductivity of the composites above the percolation threshold. In most cases, functionalized and unfunctionalized tubes yielded composites with statistically identical mechanical properties. However, composites made with functionalized tubes did have a slightly higher modulus in the rubbery plateau region at higher nanotube fractions. Small‐angle X‐ray scattering patterns indicated that the dispersion reached a plateau in the unfunctionalized composites that was consistent with the plateau in the rubbery plateau region. The room‐temperature modulus and tensile strength increase was proportionally higher than almost all increases seen previously in thermoplastic polyurethanes; however, the increase was still an order of magnitude below what has been reported for the best nanotube–polymer systems. Nanotube addition increased the hard‐segment glass transition temperature slightly, whereas the soft‐segment glass transition was so diffuse that no conclusions could be drawn. Unfunctionalized tubes suppressed the crystallization of the hard segment; whereas functionalized tubes had no effect. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 490–501, 2007     

Poly(lactic acid) composites with poly(lactic acid)‐modified carbon nanotubes

This work reports the study of the effect of chemical functionalization of carbon nanotubes on their dispersion in poly(lactic acid). The nanotubes were functionalized by the 1,3‐dipolar cycloaddition reaction, generating pyrrolidine groups at the nanotube surface. Further reaction of the pyrrolidine groups with poly(lactic acid) was studied in solution and in the polymer melt. The former involved refluxing the nanotubes in a dimethylformamide/polymer solution; the latter was carried out by direct melt mixing in a microcompounder. The carbon nanotubes collected after each process were characterized by thermogravimetry and by X‐ray photoelectron spectroscopy, showing evidence of polymer bonded to the nanotube surface only when the reaction was carried out in the polymer melt. The composites with polymer modified nanotubes present smaller average agglomerate area and a narrower agglomerate area distribution. In addition, they show improved tensile properties at low CNT concentration and present lower electrical resistivity. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3740–3750     

Synthesis of Functionalized Polynorbornanes Employing 2,5‐Bis(trifluoromethyl)‐1,3,4‐oxadiazole

Cycloaddition reaction of 2,5‐bis(trifluoromethyl)‐1,3,4‐oxadiazole with strained olefinic bonds of norbornenes was used to synthetize functionalized polynorbornanes. This simple, one step procedure was more effective when reaction was carried out by classical heating, in comparison to microwave‐assisted reactions. Various functional groups were stable in the reaction conditions (ester, imide, phthalimide, piperidyl, and carboxylic acid), whereas anhydride, N‐Boc, or TMS functionalities do not withstand reaction conditions.     

Molecular mobility of free‐radical‐functionalized carbon‐nanotube/siloxane/poly(urea urethane) nanocomposites

Multiwalled carbon nanotubes (MWNTs) were functionalized by a free‐radical reaction of vinyltriethoxysilane and were blended with poly(urea urethane) (PUU) containing poly(dimethylsiloxane) as a soft segment. PUU was end‐capped with aminopropyltriethoxysilane (A‐silane) or phenyltriethoxysilane (P‐silane).A‐silane‐end‐capped PUU was covalently bonded to functionalized MWNTs, whereas P‐silane‐end‐capped PUU was noncovalently bonded to pristine MWNTs by a π–π interaction. Fourier transform infrared, Raman spectra, and thermogravimetric analysis confirmed the functionalization of MWNTs. The results showed that the optimal reaction time of the functionalization of MWNT was 8 h, and the organic content of the modified carbon nanotubes reached 35.22%. Solid‐state nuclear magnetic resonance and dynamic mechanical analysis were used to investigate the molecular structure and molecular mobility of the carbon‐nanotube/PUU nanocomposites. A‐silane PUU covalently bonded to MWNTs showed a considerable reduction in the molecular motion of the soft segment, which led to the glass‐transition temperature decreasing from ?117 to ?127 °C as MWNTs were incorporated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6084–6094, 2005     

Synthesis of polyethylene‐grafted multiwalled carbon nanotubes via a peroxide‐initiating radical coupling reaction and by using well‐defined TEMPO and thiol end‐functionalized polyethylenes

Polyethylene (PE), alkoxyamine‐ and thiol‐terminated PEs (PE‐TEMPO and PE‐SH, respectively) can be converted to macroradicals using a peroxide, a thermal cleavage of the alkoxyamine and a hydrogen transfer reaction of the thiol, respectively. The addition of these macroradicals to multiwalled carbon nanotubes (MWCNTs) were compared by performing grafting reactions at 160 °C in 1,3‐dichlorobenzene as solvent. Raman spectroscopy was utilized to follow the introduction of PE on the MWCNTs' surface while thermogravimetric and elemental analysis indicated the extent of this grafting. The grafting ratio was found to be in the range of 19–36 wt %. PE‐functionalized MWCNTs were imaged by transmission electronic microscopy showing a PE layer with various thicknesses covering the surface of nanotubes. It was found that higher levels of grafting were obtained using PE‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy and PE‐SH rather than a radical grafting reaction in which dicumyl peroxide, PE, and MWCNTs were reacted. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011