流体组装制造的金属-碳纳米管-金属结构

基于碳纳米管的纳米器件制造中,金属-碳纳米管-金属结构是重要部分通过流体组装多壁碳纳米管,并在其上沉积、光刻图形化金属制造了金属-碳纳米管-金属结构．对比不同流体组装条件下的排列效果发现,较大的样品台倾角和较高的气流速度可实现较好的碳纳米管组装．通过对碳纳米管与金属间的接触电阻进行估算和比较,金属包覆碳纳米管比碳纳米管沉积在全电极上的接触方式具有更小的接触电阻和接触电阻分散性,且碳纳米管与金电极接触状态比钛电极好最终通过该方法制造出了接触良好的金属-碳纳米管-金属结构。     

氧化430不锈钢膦酸自组装液的溶剂含水量对自组装膜耐点蚀性能的影响

为了弄清膦酸自组装液的溶剂含水量对自组装膜性能的影响,分别以无水乙醇及其与不同含量去离子水的混合液为溶剂配制了十四烷基膦酸自组装液,通过浸泡法在氧化430不锈钢表面制备自组装膜.利用接触角测试、极化曲线、电化学交流阻抗及扫描电镜(SEM)研究了不同溶剂条件下十四烷基膦酸自组装膜的耐点蚀性能.结果表明:随自组装时间延长,膦酸自组装膜覆盖度增大,接触角增加,自组装6h时得到的自组装膜最致密,接触角最大;溶剂中水有利于形成更致密的自组装膜,随着溶剂含水量增加,膜的耐点蚀能力增强.     

自组装和分散可逆的碳纳米管圆片

通过加热碳纳米管和强酸的混合物,使碳纳米管的憎水表面发生氧化.加热含经处理的碳纳米管的悬浮液,使之脱水,得到自组装的碳纳米管圆片,该圆片可直接分散.扫描电镜图显示该圆片由局部规则排列的碳纳米管构成;红外光谱和光电子谱分析表明在化学处理过程中,碳纳米管的表面产生了含氧官能团;虽然拉曼谱测出处理过程增加了缺陷,但是X射线衍射结果表明碳纳米管类似石墨的层状结构得到保留;同时研究了经处理的碳纳米管的热稳定性.这种自组装且可分散的碳纳米管圆片为研究碳纳米管结构材料和碳纳米管复合材料提供了有效途径.     

锌微晶辅助碳纳米管图案化

利用锌微晶沸点较低易于蒸发以及形态丰富多变的特点,在微米尺度的锌晶粒介入下采用两种方式实现碳纳米管的组装.方法一:先蒸发得到一定尺度的锌微晶,然后以其为牺牲模板基于化学气相沉积生长技术实现碳纳米管的原位组装;方法二:与方法一的工艺过程相反,先在SiO2基片上气相沉积获得定向碳纳米管膜,然后以其为基板蒸发沉积锌微米晶对生长后的碳纳米管膜进行形貌调控和组装.结果表明,尽管两种组装方式的过程和原理不同,但都可获得碳纳米管的组装图案,且过程简单可控.这一技术可为碳纳米管的组装提供新途径.     

碳纳米管/环氧树脂复合材料的静电自组装制备及性能

采用静电自组装法制备了均匀分散的碳纳米管环氧树脂复合材料,并对比分析了普通碳纳米管和功能化碳纳米管对环氧树脂热学和电学性能的影响。采用透射电镜(TEM)观察到碳管和树脂乳液自组装形成"葡萄藤"状结构,扫描电镜(SEM)观察发现,碳管可在环氧树脂中均匀分散并形成网络。电、热性能研究发现,添加3%普通碳纳米管可降低环氧树脂表面电阻率7个数量级,导热系数较纯树脂提高112%,而羧基化碳纳米管表面电阻率仅降低4个数量级,导热系数仅提高86%。     

碳纳米管/聚砜共混超滤膜的制备与表征

多壁碳纳米管(MWNTs)首先经硫酸/硝酸混酸处理,然后与5-异氰酸酯-异酞酰氯反应,得到改性碳纳米管.将改性碳纳米管分散于N,N-二甲基乙酰胺(DMAc)中,再与聚砜(PSF)的DMAc溶液混和,以水为凝胶浴,制备碳纳米管/共混超滤膜.共混膜通过全反射红外光谱、扫描电镜、原子力显微镜、渗透性能测试与静态吸附实验测定.结果表明:铸膜液相转化的过程中荷电基团将更倾向于在膜表面聚集,可在温和条件下实现碳纳米管在膜表面的有序排布,使碳纳米管/聚砜超滤膜接触角变小,表面变光滑.     

碳纳米管的自组装研究进展

用自组装技术组装的碳纳米管具有新奇的光、电、催化等功能和特性，因此具有良好的发展前景。近年来，许多方法已经用于碳纳米管的组装；综述了化学吸附自组装、静电自组装、模板辅助自组装及DNA操纵下的自组装等几种主要的碳纳米管的组装方法，并对各种方法的特点及研究现状进行了评述。     

碳纳米管分散性研究现状

介绍了碳纳米管的分散方法,主要包括机械方法、共价化学修饰和非共价化学修饰方法等。机械分散和共价化学修饰对碳纳米管在溶液中的分散起到了一定的作用,然而机械分散造成碳纳米管的短切和共价化学修饰对碳纳米管电子特性的破坏,均暴露出这两种方法的局限性,而表面活性剂对碳纳米管结构的非共价化学修饰因保证了碳纳米管结构的完整性,故广泛应用于碳纳米管分散中。同时也总结了已有的碳纳米管分散液表征方法,指出目前碳纳米管分散性研究存在的不足。     

钙黄绿素自组装膜制备及其对汞离子测定

以石英基片作为基底采用硅烷化方法,通过Si-O键组装上γ-氨基丙基三乙氧基硅烷(KH550),再利用吸附作用力将壳聚糖组装为第二层,最后将荧光试剂钙黄绿素通过与壳聚糖的酯化反应间接组装在石英基底表面,构建新型钙黄绿素自组装膜。结合荧光分析法将具有荧光特性的钙黄绿素自组装膜对汞离子检测。实验结果表明所构建的钙黄绿素自组装膜对浓度在0~3.00×10-6 mg/L汞离子具有线性关系,检出限为3.25×10-8 mg/L,钙黄绿素自组装膜法检出限低、灵敏度高、反应速度快、稳定性好,并应用此方法进行了水样中汞的检测。     

高浓度石墨烯水系分散液及其气液界面自组装膜

通过测试石墨烯分散液的吸光度,比较了几种表面活性剂分散石墨烯的能力.结果表明:聚乙烯吡咯烷酮(PVP)这种"绿色"、低成本的表面活性剂,具有很好的分散能力.通过提高PVP溶液浓度,可以得到浓度高达～1.3mg/mL的石墨烯分散液,这种高浓度石墨烯分散液可以在气液界面自组装得到石墨烯膜,这种无支撑石墨烯膜具有平整的表面和规则的结构,在很多领域都有良好的潜在应用价值.     

Influence of surface chemistry on inkjet printed carbon nanotube films

Carbon nanotube ink chemistry and the proper formulation are crucial for direct-write printing of nanotubes. Moreover, the correct surface chemistry of the self-assembled monolayers that assist the direct deposition of carbon nanotubes onto the substrate is equally important to preserve orientation of the printed carbon nanotubes. We report that the successful formulation of two single walled carbon nanotube (SWNT) inks yields a consistent, homogenous printing pattern possessing the requisite viscosities needed for flow through the microcapillary nozzles of the inkjet printer with fairly modest drying times. The addition of an aqueous sodium silicate allows for a reliable method for forming a uniform carbon nanotube network deposited directly onto unfunctionalized surfaces such as glass or quartz via inkjet deposition. Furthermore, this sodium silicate ingredient helps preserve applied orientation to the printed SWNT solution. Sheet resistivity of this carbon nanotube ink formula printed on quartz decreases as a function of passes and is independent of the substrate. SWNTs were successfully patterned on Au. This amine-based surface chemistry dramatically helps improve the isolation stabilization of the printed SWNTs as seen in the atomic force microscopy (AFM) image. Lastly, using our optimized SWNT ink formula and waveform parameters in the Fuji materials printer, we are able to directly write/print SWNTs into 2D patterns. Dried ink pattern expose and help orient roped carbon nanotubes that are suspended in ordered arrays across the cracks.     

Selective atomic layer deposition of metal oxide thin films on patterned self-assembled monolayers formed by microcontact printing

We demonstrate a selective atomic layer deposition of TiO2, ZrO2, and ZnO thin films on patterned alkylsiloxane self-assembled monolayers. Microcontact printing was done to prepare patterned monolayers of the alkylsiloxane on Si substrates. The patterned monolayers define and direct the selective deposition of the metal oxide thin films using atomic layer deposition. The selective atomic layer deposition is based on the fact that the metal oxide thin films are selectively deposited only on the regions exposing the silanol groups of the Si substrates because the regions covered with the alkylsiloxane monolayers do not have any functional group to react with precursors.     

Chemical optimization of self-assembled carbon nanotube transistors

We present the improvement of carbon nanotube field effects transistors (CNTFETs) performances by chemical tuning of the nanotube/substrate and nanotube/electrode interfaces. Our work is based on a method of selective placement of individual single walled carbon nanotubes (SWNTs) by patterned aminosilane monolayer and its use for the fabrication of self-assembled nanotube transistors. This method brings a relevant solution to the problem of systematic connection of self-organized nanotubes. The aminosilane monolayer reactivity can be used to improve carrier injection and doping level of the SWNT. We show that the Schottky barrier height at the nanotube/metal interface can be diminished in a continuous fashion down to an almost ohmic contact through these chemical treatments. Moreover, sensitivity to 20 ppb of triethylamine is demonstrated for self-assembled CNTFETs, thus opening new prospects for gas sensors taking advantages of the chemical functionality of the aminosilane used for assembling the CNTFETs.     

硅基图案化HfO2表面微结构的制备和表征

结合光刻印技术和HfO2液相自组装沉积成膜技术,在单晶硅表面成功地制备了具有微米级图案结构的HfO2薄膜,该硅基图案化HfO2微结构近来在工业界特别是微电子领域引起极度的关注.X射线衍射(XRD)与扫描电镜(SEM)显示,在图案区域成功制备了HfO2薄膜,EDS能谱测试显示了图案区域的HfO2薄膜的化学组成.     

Directed assembly of functional light harvesting antenna complexes onto chemically patterned surfaces

We report the directed assembly of the photosynthetic membrane proteins LH1 and LH2 isolated from the purple bacterium Rhodobacter sphaeroides onto chemically patterned substrates. Nanoimprint lithography was used to pattern discrete regions of amino-?and fluoro-terminated or poly(ethylene glycol) self-assembled monolayers onto a glass substrate. Densely packed layers of assembled protein complexes were observed with atomic force microscopy. The protein complexes attached selectively to the amino-terminated regions by electrostatic interactions. Spectral images generated with a hybrid scanning probe and fluorescence microscope confirmed that the patterned proteins retained their native optical signatures.     

Creating nanopatterns of His-tagged proteins on surfaces by nanoimprint lithography using specific NiNTA-histidine interactions

Directed assembly of the DsRed FT protein is demonstrated on self-assembled monolayers (SAMs) on silicon substrates patterned by nanoimprint lithography. Initially, the DsRed protein is attached using electrostatic interactions on both topographical (polymer) templates with an amino functionalization and on chemically patterned (flat) substrates. In a second experiment, a patterned NiNTA SAM is used in order to attach the DsRed FT protein via supramolecular interactions, taking advantage of the histidine functionalization of the DsRed FT protein. The NTA SAM is formed on silicon oxide using a multistep covalent process. Patterning of the NTA SAM is performed using nanoimprint lithography. The DsRed FT protein is attached on the patterned NTA layer after treating this with a Ni(II) solution. Moreover, the histidine-NiNTA binding may be reversed by removing the Ni using EDTA or by competition using imidazole. The regeneration and reuse of the substrate by subsequently attaching and removing two different histidine-functionalized proteins from the patterned NTA is shown by fluorescence microscopy.     

Carbon nanotube scanning tunneling microscopy tips for chemically selective imaging

Carboxyl-terminated single-walled carbon nanotubes (SWNTs) were successfully immobilized from solution phases onto the apexes of gold tips for scanning tunneling microscopy (STM). Gold STM tips were first modified with self-assembled monolayers of 4-mercaptobenzoic acid, and its carboxyl groups were used to anchor carboxylated SWNTs through Zn2+ ion-bridged coordination. These SWNT tips gave high-resolution STM images of a diether monolayer formed on the graphite surface. In addition and more importantly, the ether oxygens of the sample molecules were selectively observed as bright spots with the SWNT tips with significantly high reproducibility, which is due to the facilitation of electron tunneling through hydrogen bond interactions between the ether oxygens and carboxyl groups at the end of the SWNT tips.     

Self-assembled interconnection by bamboo-like carbon nanotubes

Carbon nanotubes (CNTs) could be formed on Si substrate using nickel catalyst under microwave plasma-enhanced chemical vapor deposition system. Under the high, negative-bias voltage (−400 V) condition, we found the formation of the carbon nanotube islands and the bamboo-like carbon nanotube interconnection lines. Most of the bamboo-like carbon nanotubes connected with the carbon nanotubes themselves, which indicates the self-assembled characteristics of the carbon nanotube interconnection lines. The self-assembled characteristics of the bamboo-like carbon nanotube interconnection lines were evaluated using computer-aided image analysis.     

Immobilization of carbon nanotubes on functionalized graphene film grown by chemical vapor deposition and characterization of the hybrid material

We report the surface functionalization of graphene films grown by chemical vapor deposition and fabrication of a hybrid material combining multi-walled carbon nanotubes and graphene (CNT–G). Amine-terminated self-assembled monolayers were prepared on graphene by the UV-modification of oxidized groups introduced onto the film surface. Amine-termination led to effective interaction with functionalized CNTs to assemble a CNT–G hybrid through covalent bonding. Characterization clearly showed no defects of the graphene film after the immobilization reaction with CNT. In addition, the hybrid graphene material revealed a distinctive CNT–G structure and p–n type electrical properties. The introduction of functional groups on the graphene film surface and fabrication of CNT–G hybrids with the present technique could provide an efficient, novel route to device fabrication.     

Chemical vapour deposition of single walled carbon nanotubes freely suspended over nanotube supports

Single walled carbon nanotubes (SWNTs) suspended above the substrate can be fabricated simply and rapidly by chemical vapour deposition growth over pre-grown multi-walled carbon nanotubes (MWNTs). SWNTs are suspended either on a randomly organized carbon nanotube network on an unpatterned substrate, or between organized pillars made from vertically aligned nanotube forests on a patterned substrate. All nanotubes are produced during a single growth run using a two step growth technique. This approach enables the fabrication of laterally suspended SWNT networks which are well suited for optical applications.