表面润湿性对水润滑Al-Mg合金摩擦学特性的影响

通过自组装技术在Al-Mg合金表面制备自组装分子膜,采用接触角测量仪测定了自组装分子膜的水接触角,采用多功能摩擦磨损试验机对制备不同自组装分子膜的Al-Mg合金在3种润滑方式下进行摩擦磨损实验。结果表明,制备自组装分子膜可显著改变Al-Mg合金的表面润湿性,制备FDTS、FOTS、OTS自组装分子膜的表面呈疏水性,制备MPS、APS自组装分子膜的表面则呈亲水性,5种自组装分子膜接触角由大到小的顺序为FDTS>FOTS>OTS>MPS>APS。自组装分子膜的疏水性越强,Al-Mg合金的摩擦系数越小。同种自组装分子膜在干摩擦条件下摩擦系数最大,浸水润滑条件下摩擦系数有所下降,喷水润滑条件下摩擦系数最小。     

表面润湿性对水润滑Al-Mg合金摩擦学特性的影响

通过自组装技术在Al-Mg合金表面制备自组装分子膜,采用接触角测量仪测定了自组装分子膜的水接触角,采用多功能摩擦磨损试验机对制备不同自组装分子膜的Al-Mg合金在3种润滑方式下进行摩擦磨损实验。结果表明,制备自组装分子膜可显著改变Al-Mg合金的表面润湿性,制备FDTS、FOTS、OTS自组装分子膜的表面呈疏水性,制备MPS、APS自组装分子膜的表面则呈亲水性,5种自组装分子膜接触角由大到小的顺序为FDTS>FOTS>OTS>MPS>APS。自组装分子膜的疏水性越强,Al-Mg合金的摩擦系数越小。同种自组装分子膜在干摩擦条件下摩擦系数最大,浸水润滑条件下摩擦系数有所下降,喷水润滑条件下摩擦系数最小。     

二氧化铪晶态薄膜的自组装制备

利用自组装单层膜技术,在玻璃基板上生长有机硅烷单分子膜层,以Hf(SO4)2·4H2O和HCl配制HfO2前驱液,通过液相沉积在硅烷的功能性官能团上诱导生成二氧化铪薄膜.通过接触角测试仪、AFM、SEM及XRD等手段对膜材料的表面形貌和结构进行了研究分析.结果表明,利用自组装单层法成功制备出立方型的HfO2晶态薄膜,薄膜表面均一.     

二氧化铪(HfO_2)功能陶瓷薄膜的自组装制备

利用自组装单层膜技术,在玻璃基板上生长十八烷基三氯硅烷(OTS)单分子膜层,以Hf(SO4)2·4H2O和HCl配制HfO2前驱液,通过液相沉积在硅烷的功能性官能团上诱导生成二氧化铪薄膜.研究了紫外光照射对OTS单分子层的影响,通过接触角测试仪、AFM、SEM及XRD等手段对膜材料的表面形貌和结构进行了研究分析.结果表明,利用自组装单层法成功制备出HfO2晶态薄膜,呈立方型的HfO2,无其它杂相,薄膜表面均一.     

控制表面氧化法制备超疏水 CuO纳米花膜

采用含有过硫酸钾氧化剂和氢氧化钾的水溶液处理金属铜表面,再经空气中加热后, 在铜表面上得到了一层具有花朵状纳米结构的CuO膜．每朵纳米花由数十个长约2μm、宽约 120nm、厚约12nm的CuO纳米片自组装而成．纳米花膜经氟化处理后表现出超疏水性,接触角达到约158°．文中初步提出了纳米花形态的生长机制,并用Cassie理论对膜的润湿性进行了分析．     

Ti6Al4V表面纹理制备及其润湿性

采用激光加工技术在Ti6Al4V表面分别加工直线、网格和具有规则点阵状结构的表面纹理,采用自组装技术制备自组装分子膜。采用扫描电镜、形貌分析仪和接触角测量仪对成膜后的钛合金表面进行形貌和接触角的表征与测量。结果表明,通过激光加工和沉积自组装分子膜,可显著增大Ti6Al4V的水接触角。其中直线纹理的试样表面水接触角可达124.8°,网格纹理的试样表面接触角可达126.1°,点阵状纹理的试样表面接触角可达151.6°。表面接触角与表面粗糙度相关,随着表面粗糙度值的增大,接触角呈增大趋势,当表面粗糙度>4μm时,接触角均>150°,形成超疏水表面。     

基于纳米TiO2逐层自组装的聚偏氟乙烯膜亲水化改性研究

采用逐层自组装方法,利用三乙烯四胺盐对纳米TiO2的吸附作用,把直径约20nm的TiO2颗粒逐层组装到聚偏氟乙烯（PVDF）膜表面,研究了纳米TiO2组装层数对PVDF改性膜接触角的影响,发现当组装层数为1和3时改性PVDF膜初始接触角略有增大,而随着冻结时间延长改性PVDF膜接触角显著减小。当组装层数为5时PVDF改...     

四方相BaTiO3薄膜的自组装制备与表征

以(NH₄)₂TiF₆、 Ba(NO₃)₂ 和H₃BO₃为主要原料, 采用自组装单层膜(SAMs)技术, 以三氯十八烷基硅烷(octadecyl-trichloro-silane, OTS)为模版, 在玻璃基片上制备了四方相钛酸钡晶态薄膜. 改性基板的亲水性测定与原子力显微镜（AFM）测试表明, 紫外光照射使基板由疏水转变为亲水, 能够对OTS-SAM起到修饰作用. 金相显微镜观察结果显示,OTS单分子膜指导沉积的薄膜样品表面均匀, 表明OTS SAM对钛酸钡薄膜的沉积具有诱导作用; X射线衍射（XRD）与扫描电镜（SEM）表征显示, 空气中600℃下保温2h实现了薄膜由非晶态向四方相BaTiO₃晶态薄膜的转化过程, 制备的钛酸钡薄膜在基板表面呈纳米线状生长, 线长约在500～1000nm之间, 相互连接的晶粒大小约为100nm. 文章同时对自组装单层膜和钛酸钡薄膜的形成机理进行了探讨.     

静电组装法在纳米SiO_2表面构筑高分子刷的合成与表征(英文)

本文采用静电自组装技术在表面阳离子化的SiO2粒子（SiO2-CBAFS）上构筑了高分子刷,并采用核磁、红外、热失重、接触角和原子力显微镜分别表征了组装粉体的结构、组装量以及自组装单层膜的组装行为和表面拓扑形貌。研究结果表明,采用静电自组装技术可以成功地在SiO2-CBAFS上构筑组装量高达27％的高分子刷,远远高于国际上已见报道的采用共价键合法构筑的高分子刷的组装量（20％）。研究发现,组装量随聚合物（PS-NH—SO3Na）分子量呈非线性增长,其组装行为受到PS-NH—SO3Na的分子量和溶液浓度的影响。     

硅基双层复合自组装分子膜结构特性及其润湿行为的分子动力学模拟

用分子动力学方法模拟了单晶硅（Si）表面N-3-（三甲氧基硅烷基）丙基乙二胺（DA）-月桂酰氯（LA）（DA-LA）双层复合自组装分子膜（SAMs）的结构特性,得到膜层中DA和LA分子的最佳覆盖率及分布情况。进一步讨论了水滴在DA-LA双层复合SAMs表面的润湿过程,通过接触角和径向分布函数等参量对其润湿行为进行了分析。研究表明：DA分子在Si上覆盖率为50%、LA分子在DA自组装单分子膜（DA SAM）上接枝率为100%时,分子膜呈有序排布,体系能量最低,从分子角度揭示了Si表面覆盖致密SAMs的形成机制。当取最佳覆盖率体系进行润湿机制模拟时,DA-LA双层复合SAMs表面水滴接触角与实验值相似,表现出良好的疏水性。而DA SAM表面由于DA分子短而稀疏,暴露出底层更亲水的羟基分子,从而导致所得接触角较实验偏小;经测量及计算得出,羟基化Si表面自由能最高,表现出较强的亲水性;DA表面次之;DA-LA表面自由能最低,表现出良好的疏水性。进一步分析发现：羟基化Si表面、DA SAM表面与水滴间存在氢键,加强了表面的亲水性,而DA-LA双层复合SAMs表面与水滴间只存在弱范德华力,有利于表面呈现疏水性。     

Kinetics of epitaxial growth and roughening

We review some recent results on epitaxial growth and surface roughening. Particular emphasis is placed on the concept of the critical island size in submonolayer growth and on the existence of scaling in both the submonolayer and multilayer growth regimes. The use of scaling ideas as well as Monte Carlo simulations and continuum equations is shown to be effective in understanding experimental results for submonolayer growth and surface roughening.     

The Pattern Growth of Carbon Nanotubes by Self-assembled Monolayers Techniques

The well controllable selective growth of carbon nanotubes (CNTs)on the desired area is an important issue for their future applications. In this study, a novel method for selective growth of CNTs was proposed by using the technology of self-assembly monolayers (SAMs) and the Fe-assisted CNTs growth. The Si wafers with the a: Si/Si3N4 layer patterns were first prepared by low pressure chemical vapor deposition (LPCVD)and lithography techniques to act as the substrates for selective deposition of SAMs. The selectivity of SAMs from APTMS solution (N-(2-aminoethyl)-3-aminopropyltrimethoxsilane) is based on its greater reactivity of head group on a-Si than Si3N4 films. The areas of pattern with SAMs will first chelate the Fe3 ions by their diamine-terminated group. The Fe3 ions were then consolidated to become Fe-hydroxides in sodium boron hydride solution to form the Fe-hydroxides pattern. Finally, the Fe-hydroxides pattern was pretreated in H plasma to become a well-distributed Fe nano-particles on the surface, and followed by CNTs deposition using Fe as catalyst in a microwave plasma-chemical vapor deposition (MP-CVD) system to become the CNTs pattern. The products in each processing step, including microstructures and lattice images of CNTs, were characterized by contact angle measurements, scanning electron microscopy(SEM), XPS, Auger spectroscopy, transmission electron microscopy (TEM) and high resolution TEM (HRTEM)deposition. The results show that the main process parameters include the surface activation process and its atmosphere, consolidation time and temperature, H plasma pretreatment. The function of each processing step will be discussed.     

The Pattern Growth of Carbon Nanotubes by Self-assembled Monolayers Techniques

The well controllable selective growth of carbon nanotubes (CNTs)on the desired area is an important issue for their future applications. In this study, a novel method for selective growth of CNTs was proposed by using the technology of self-assembly monolayers (SAMs) and the Fe-assisted CNTs growth. The Si wafers with the a ： Si/Si3N4 layer patterns were first prepared by low pressure chemical vapor deposition (LPCVD)and lithography techniques to act as the substrates for selective deposition of SAMs. The selectivity of SAMs from APTMS solution (N-(2-aminoethyl)-3-aminopropyltrimethoxsilane) is based on its greater reactivity of head group on a-Si than Si3N4 films. The areas of pattern with SAMs will first chelate the Fe3 ions by their diamine-terminated group. The Fe^3 ions were then consolidated to become Fe-hydroxides in sodium boron hydride solution to form the Fe-hydroxides pattern. Finally, the Fe-hydroxides pattern was pretreated in H plasma to become a well-distributed Fe nano-particles on the surface, and followed by CNTs deposition using Fe as catalyst in a microwave plasma-chemical vapor deposition (MP-CVD) system to become the CNTs pattern. The products in each processing step, including microstructures and lattice images of CNTs, were characterized by contact angle measurements, scanning electron microscopy (SEM), XPS, Auger spectroscopy, transmission electron microscopy (TEM) and high resolution TEM (HRTEM) deposition. The results show that the main process parameters include the surface activation process and its atmosphere, consolidation time and temperature, H plasma pretreatment. The function of each processing step will be discussed.     

Stability of self-assembled monolayers of organothiol mono and bipode on copper in presence of another organothiol solution

The stability of alkanethiol self-assembled monolayers (SAMs) on metallic substrates is an important aspect for further application. Some studies point out the poor stability of this coating and the displacement of alkanethiol from the monolayer by immersion in another alkanethiol solution.The aim of this work consists in a comparative investigation of self-exchange of three organothiols: 11-perfluorobutyl-1-thiol-undecane (or R_fSH), 2-dodecylpropane-1,3-dithiol (or R(SH)₂) and n-decanedithiocarboxylic (or RS₂H).The immersion of RS₂H monolayer into R_fSH solution (first approach) leads to the incorporation of thiol molecules into the defects of the initial SAMs followed by the displacement of RS₂H molecules by R_fSH. While for R_fSH SAM in presence of R(SH)₂ solution (second approach), longer time of immersion is required to observe the incorporation of dithiol molecules into the coating as well as the displacement of thiol molecules.     

Field emission microscopy of graphene on iridium point emitter

The field electron emission from the surface of an iridium point emitter covered by a monolayer graphene film has been studied. An analysis of the field emission images showed that electron emission takes place at the boundaries between graphene islands with dimensions up to several dozen nanometers. Intercalation of alkali metal (cesium) atoms under the graphene film decreases the work function of the emitter but does not change the image. Field ion desorption images obtained in the fields where the surface diffusion of Cs atoms is impossible reveal the presence of a submonolayer concentration of cesium at the defects representing graphene island contacts.     

Growth and intermixing of Nb on Fe(110) and Fe on Nb(110)

The growth system Nb/Fe and the reversed system Fe/Nb were studied on the (110) surface using Scanning Tunneling Microscopy (STM). For Nb/Fe(110) we present in situ STM results as a direct evidence of a Nb/Fe exchange mechanism at temperatures above 400 K that leads to the formation of a surface alloy.

Since the experiments on Nb(110) were done on Nb buffer layers the fabrication of those is discussed. We show that besides Al₂O₃ (112¯0) wafers a W(110) single crystal can serve as a support for Nb(110) buffer layers which is more convenient for STM measurements. The niobium oxide adlayer that is present on nearly all Nb surfaces can be avoided by thorough degassing of the Nb source.

Results on Fe/Nb(110) are discussed in the temperature range from room temperature (RT) to 1000 K. At RT no intermixing of Fe and Nb was observed and with very low deposition rates epitaxial films can be grown. An ordered dislocation network was observed in the first Fe layers. Above 800 K two adatom island species are present as the manifestation of an alloying process. The formation of an Fe–Nb surface alloy which in the submonolayer regime is interspersed with chains of pure Fe is suggested.     

Functionalization of silicon dioxide surface with 3-aminopropyltrimethoxysilane for fullerene C60 immobilization

Formation of self-assembled monolayers (SAM) of 3-aminopropyltrimethoxysilane (APTMS), chemically bonded to silicon dioxide surface, using a new solvent free process, has been studied by contact angle measurements, ellipsometry, ATR-FTIR spectroscopy and AFM imaging. The possibility of using as-obtained APTMS SAMs for anchoring functional molecular moieties is then studied with fullerene C60. In a first part we have analyzed the grafting kinetics of APTMS SAMs in order to control the formation of a single monolayer. Results show that about four hours are needed to obtain a complete APTMS single monolayer. In parallel, the ordering kinetics of the SAM has been monitored by ATR-FTIR spectroscopy, showing that the monolayer reaches its final order before grafting. We show that those APTMS SAMs can be used to graft C60 molecules deposited from a solution and forming about one monolayer anchored on amine terminal moieties. Such results could help paving the way to the preparation of hybrid C60-based molecular devices on silicon through a bottom-up approach.     

Forming microstructured alkanethiol self-assembled monolayers on gold by laser ablation

A process to form microstructured alkanethiol self-assembled monolayers (SAMs) on gold is described. It is well known that alkanethiols spontaneously form homogenous SAMs on gold surfaces. By means of laser ablation, the exposed areas of alkanethiol monolayers can be removed from the gold surface. Free gold is obtained which can react further with second and third thiols. By this technique, structured alkanethiol SAMs are obtained reliably and easily. In a rather narrow window of pulse intensities, in our example 120$hboxMW/cm^2pm hbox10%$from a frequency-doubled Nd : YVO$_4$laser with 6-ns pulsewidth operating at a repetition rate of 20 kHz, ablation of alkanethiol monolayers is obtained without causing any damage to the gold substrate. Examples are presented where lines down to 10$muhbox m$in width were laser ablated into an SAM formed either from a hydrophilic or a hydrophobic alkanethiol and filled with a monolayer of a second alkanethiol of opposite hydrophilicity. The patterned structures were examined by optical and fluorescence microscopy as well as by lateral force microscopy. The presented method enables the preparation of microstructured SAMs on gold and probably on a wide variety of other substrates.     

Immobilisation of cobaltferritin onto gold electrode based on self-assembled monolayers

The iron storage protein, ferritin, has a cavity of ～7?nm in diameter in which iron is oxidised and stored as a hydrated oxide core. Electron transfer is known to be an important step in the sequestering of iron by cellular ferritin. The cavity was used as a nanocontainer to grow cobalt nanoparticles. The immobilisation of ferritin on the electrode surface is essential for various bioelectronic applications. A cobaltferritin-immobilised electrode based on self-assembled monolayer (SAM)-modified gold electrode was developed. The cobaltferritin-immobilised SAM-modified electrode was characterised by electrochemical and atomic force microscopy (AFM) techniques. The results indicated that cobaltferritin was selectively immobilised onto succinimidyl alkanedisulfide-modified Au electrode by the covalent interaction between cobaltferritin and the terminal functional groups of the SAMs. The cobaltferritin immobilised modified electrode showed a direct electron transfer reaction between cobaltferritin and the electrode. The electrochemically regulated uptake and release of cobalts for cobaltferritin immobilised on the SAMs were demonstrated. The results obtained in this study indicate that cobaltferritin has potential for a biomaterial in nanoscale synthesis for potential magnetic, catalytic and biomedical-sensing applications.     

Fast and simultaneous growth of graphene,intermetallic compounds,and silicate on Cu–Ni alloy foils

A graphene bilayer was grown on copper–nickel alloy foils (30 at-% Ni: 70 at-% Cu designated as a 30Ni–70Cu) via an inductively coupled plasma–chemical vapor deposition chamber, and was characterized. The first layer fully covered the foil, while there was partial coverage of the second layer. At the same time, the alloy catalyst produced a compound of magnesium silicate in some regions and of copper sulfide in other regions on which a graphene monolayer simultaneously grew without any discontinuity or boundaries of the 1st graphene monolayer between simultaneous growth and graphene-only growth regions. Compared with Cu foils, the alloy foils led to faster growth of the graphene film in graphene-only growth regions, while maintaining the same quality, homogeneity, and thickness uniformity as a monolayer graphene grown on Cu. Raman spectroscopy and scattering demonstrated that the 2D and D bands of the Raman spectra were in the same position for the monolayer graphene on 30Ni–70Cu regardless of the grown regions and for the graphene on the Cu with a full width at half maximum of ∼38 cm⁻¹ ranging from 30 to 55 cm⁻¹ of 2D, and without a D band in the spectra of the graphene monolayer and bilayer. Thus the resulting graphene growth is affected primarily by the Cu catalyst, partly by the compounds grown simultaneously with the graphene monolayer on the foil surface via thermal reactions of the impurities dissolved in the alloy matrix, and partly by the Ni. The quality of the graphene is dependent on the major composition of Cu catalyst in the alloy foils. On the other hands, the alloying element of Ni governs the growth kinetics unless the alloy foils is covered with the intermetallic compounds and silicate.