C60自组装单分子膜的摩擦行为研究

随着高新技术的发展对润滑提出了更高要求 ,借助分子自组装技术 ,期望把长链化合物或聚合物的一端置入摩擦表面 ,形成一层“分子刷” ,以达到降低摩擦磨损的目的。这一概念在纳米摩擦学中尤其引人注目。即利用化学的方法 ,在诸如ＭＥＭｓ等机件摩擦表面建立起一层高度定向致密的超薄有机膜 ,以减少其摩擦损伤 ,延长使用寿命。可以预计分子自组装技术对纳米摩擦学基础及应用研究将将起到巨大的推动作用。本工作选用含端氨基的氨基酸在银基底形成的自组装膜表面通过氨基与Ｃ6 0反应制备了Ｃ6 0单分子膜 ,研究了Ｃ6 0分子自组装膜的微观摩擦行…     

极性自组装单层膜取向铁电液晶器件

采用极性自组装单层膜和摩擦的方法制备了非对称的液晶盒.在铁电液晶相变的过程中不施加电场,得到了排列均一的铁电液晶器件.实验表明:极性自组装单层膜极性越大器件的对比度越高.经过分析得出该器件液晶分子取向机理为:基板附近的铁电液晶通过偶极和极性自组装膜的作用,使得靠近自组装膜表面处的偶极和靠近摩擦表面的偶极的指向相同,通过分子的相互作用使得体内分子排列方向一致.     

基于分子印迹聚合膜的胆固醇丝网印刷生物传感芯片

该文基于自组装技术在丝网印刷金电极表面制备分子印迹膜,研制胆固醇电化学仿生生物传感芯片。利用扫描电镜(SEM)对平面裸金电极、厚膜裸金电极及其修饰电极进行了形貌的分析比较,采用循环伏安分析法对电极修饰过程的电化学特性进行表征,采用计时电流法对胆固醇生物传感芯片的浓度响应特性进行检测。结果表明, 基于丝网印刷工艺的厚膜电极不仅能满足自组装分子印迹仿生膜的修饰,而且电极表面具有明显的纳米放大效应。传感器对0~700 nM不同浓度胆固醇进行检测,线性范围50 nM~700 nM,灵敏度达到-4.94 A/[lg(nM)],线性相关系数为0.994。该胆固醇传感芯片具有较高的准确性,检测准确度达到了99.56%。     

海藻酸钠自组装体系的AFM研究

运用原子力显微镜(AFM)对不同浓度海藻酸钠在云母表面上形成的自组装膜进行了研究,实验结果显示在0．001mg／ml时,海藻酸钠出现单分子聚集体形态;0.01mg／ml和0.05mg／ml时,呈现致密、紧凑的网格状结构。随着浓度的改变,海藻酸钠自组装表面超微结构也发生变化。初步分析了影响其表面超微结构变化的一些因素并运用耗散理论探讨了这种变化过程可能的机理。     

基于多重分形谱研究十二烷基硫醇分子自组装膜在铜表面的作用行为

采用动电位扫描、原子力显微镜相位测试,基于多重分形谱,研究了十二烷基硫醇分子自组装膜在铜表面的作用行为。结果表明,在氯化钠溶液中,十二烷基硫醇分子自组装膜对铜腐蚀有显著的抑制效果,缓蚀效率随自组装时间的增加而增大。采用原子力显微镜对样品进行相位图测试,基于多重分形谱对相位图进行分析,可反映出随着自组装时间的增加,自组装膜在铜表面从部分覆盖到完全覆盖的过程。     

碳纳米管在APTES自组装膜表面沉积的研究

基于碳纳米管(CNTs)能沉积到3-氨丙基三乙氧基硅烷(APTES)自组装膜表面而定位,采用自组装方法,在硅基底上制备了具有氨基表面的APTES自组装膜。将APTES自组装膜浸入碳纳米管分散液(N,N-二甲基甲酰胺,DMF)中,实现了CNTs在APTES自组装膜上的沉积。实验发现,温度、时间以及CNTs在分散液中的浓度等因素对碳纳米管在APTES自组装膜上的沉积有很大影响。结果表明,延长沉积时间、提高沉积温度和CNTs在分散液中的浓度均能增强CNTs在自组装膜上的沉积,为进一步有效控制CNTs定位和构建基于CNTs结构的纳米电子器件提供了帮助。     

不同基底上Au纳米粒子的2D组装与AFM表征

从Au纳米粒子出发,利用竖直浸渍提拉法(dip-coating)成功将Au纳米粒子负载于基底(云母片/单晶硅片),并以3-氨丙基三甲氧基硅烷(APTMS)对单晶硅片进行改性,得到具有密度分布不同的Au纳米粒子two dimensional(2D)组装结构,制备方法简单易行。利用原子力显微镜(AFM)表征了不同制备条件下Au纳米粒子在基底表面的分布状态,结果表明,Au纳米粒子溶胶和偶联剂APTMS的浓度以及浸渍时间对Au纳米粒子在单晶硅片表面的密度分布起到决定性作用。     

Drude-Lorentz色散模型研究光学Tamm态的性质

为了获得光学Tamm态(OTS)的特性,建立了一种银-光子晶体-银结构,并利用银的Drude-Lorentz色散模型和特征矩阵法研究了该结构中OTS的波长特性和吸收特性.结果表明,在该结构中存在两个OTS,分别称为OTS1和OTS2.OTS1和OTS2的中心波长随入射角的增加向短波方向移动,OTS1和OTS2的中心波长间距随着入射角的增加而减小.OTS1和OTS2中心波长随银层厚度的增加向短波方向移动,OTS1和OTS2的波长宽度都随银层厚度的增加而减小.OTS1和OTS2都具有较大的吸收率,OTS1和OTS2的吸收率随银层厚度有着相似的变化规律.这些特性的获得加深了对银-光子晶体-银结构中光学Tamm态特性的认识.     

稀土La自组装纳米膜的制备及表征

电子封装表面材料采用分子自组装技术制备了稀土La纳米膜,采用AFM(原子力显微镜)对组装膜的表面形貌进行表征,表征结果该稀土纳米膜表面形貌致密,表面粒子尺寸为20～30nm;场发射扫描电镜测试表明,该组装膜的成分为La;     

硫醇自组装多晶金表面AFM图像的分形研究

本文针对多晶粗糙电极表面自组装膜（SAM）体系,提出了利用原子力显微镜（AFM）相图分形维数进行表征的新方法。首先对自组装多晶金电极进行了交流阻抗测试,结果表明随着乙醇自组装液中十二烷基硫醇（C12SH）浓度增大,自组装膜中缺陷面积减少,趋向于形成完整致密的单分子层吸附膜。而对组装电极AFM图像的分形研究表明,在不同C12SH浓度条件下,电极表面高度图分形维数无明显变化,相图却呈现不同的分形特征,且体现的变化规律与交流阻抗测试结果一致,证实了AFM相图分形维数表征法研究粗糙金表面硫醇自组装膜吸附行为的可行性,为粗糙表面分子吸附行为的AFM研究提供了新思路。     

SAM Functionalized ZnO Nanowires for Selective Acetone Detection: Optimized Surface Specific Interaction Using APTMS and GLYMO Monolayers

In modern days, self‐assembled monolayer (SAM) functionalized surfaces represent an interesting tool for the development of ultrasensitive and selective sensing platforms for the detection of chemical substances such as biomolecules and gases. The ability of SAM to generate different functional groups on a single surface such as zinc oxide (ZnO) can be used to immobilize biomolecules and detect different analytes such as gases, proteins, etc. Herein, SAM functionalized ZnO NW‐based sensors are developed for acetone exhaled breath analysis. ZnO NWs are synthesized using a vapor–liquid–solid mechanism and their functionalization is done with two different SAMs, i.e., (3‐aminopropyl)trimethoxysilane (APTMS) and 3‐glycidoxypropyltrimethoxysilane (GLYMO). The enhancement in the electron depletion layer resistance (and also width) due to the capturing of electrons from the ZnO NWs surface by APTMS and GLYMO molecules is found to be the major reason in their superior sensing performances. The amine (–NH₂) groups of APTMS monolayer enhance the sensors selectivity toward acetone due to their reactions with acetone molecules, which produce imine in addition to water molecules. Moreover, after the functionalization with APTMS SAMs, the detection limits of the sensors are improved from 6 to 0.5 ppm, which makes these devices potential candidates for acetone exhaled breath analysis.     

Carrier mobility in pentacene as a function of grain size and orientation derived from scanning transmission X-ray microscopy

Pentacene field-effect transistors were prepared on silicon nitride membranes for scanning transmission X-ray microscopy (STXM) investigations. The membranes were modified by different self-assembled monolayers (SAMs). Pentacene was deposited atop the SAM-treated membrane and the in-plane orientation of the grains were subsequently investigated by polarization dependent STXM measurements. The grain sizes were determined and compared to those obtained from atomic force microscopy (AFM) measurements. Statistical analysis of the grain orientation was correlated with the charge carrier mobility of the films, in which we observed an increase in the mobility with increasing grain size and decreasing surface roughness of the SAM.     

Nanoporous Substrate‐Infiltrated Hydrogels: a Bioinspired Regenerable Surface for High Load Bearing and Tunable Friction

Nature has successfully combined soft matter and hydration lubrication to achieve ultralow friction even at relatively high contact pressure (e.g., articular cartilage). Inspired by this, hydrogels are used to mimic natural aqueous lubricating systems. However, hydrogels usually cannot bear high load because of solvation in water environments and are, therefore, not adopted in real applications. Here, a novel composite surface of ordered hydrogel nanofiber arrays confined in anodic aluminum oxide (AAO) nanoporous template based on a soft/hard combination strategy is developed. The synergy between the soft hydrogel fibers, which provide excellent aqueous lubrication, and the hard phase AAO, which gives high load bearing capacity, is shown to be capable of attaining very low coeffcient of friction (<0.01) under heavy load (contact pressures ≈2 MPa). Interestingly, the composite synthetic material is very stable, cannot be peeled off during sliding, and exhibits desirable regenerative (self‐healing) properties, which can assure long‐term resistance to wear. Moreover, the crosslinked polymethylacrylic acid hydrogels are shown to be able to promptly switch between high friction (>0.3) and superlubrication (≈10^?3) when their state is changed from contracted to swollen by means of acidic and basic actuation. The mechanisms governing ultralow and tunable friction are theoretically explained via an in‐depth study of the chemomechanical interactions responsible for the behavior of these substrate‐infiltrated hydrogels. These findings open a promising route for the design of ultra‐slippery and smart surface/interface materials.     

Probe‐Based Electro‐Oxidative Lithography of OTS SAMs Deposited onto Transparent ITO Substrates

Transparent conductive oxides like indium tin oxide (ITO) play a pivotal role in a wide range of innovative applications, such as new generations of solar cells. In many of these applications the tailoring of surface properties on the nanometer scale represents a highly desirable target. The local oxidation of self‐assembled monolayers (SAMs) using a scanning probe is a promising technique to achieve surface modifications on the nanometer scale. So far, electro‐oxidative lithography of SAMs has been reported mainly on Si wafers while there are no previous reports on transparent oxides. Here, we report the oxidative lithography of n‐octadecyltrichlorosilane (OTS) SAM deposited onto an ITO layer. A local overoxidation of the substrate is observed while the simultaneously occurring monolayer oxidation is indirectly confirmed by the site‐selective deposition of silver nanoparticles onto electro‐oxidized areas. The process of lithography is compared to that on OTS‐Si substrates and its mechanism is systematically investigated by means of scanning Kelvin probe microscopy (SKPM).     

Electronic Transport in Molecular Self-Assembled Monolayer Devices

A review on the mechanisms and characterization methods of electronic transport through self-assembled monolayers (SAMs) is presented. Using SAMs of alkanethiols in a nanometer-scale-device structure, tunneling is unambiguously demonstrated as the main intrinsic conduction mechanism for defect-free large bandgap SAMs, exhibiting well-known temperature and length dependencies. In-elastic electron tunneling spectroscopy exhibits clear vibrational modes of the molecules in the device, presenting direct evidence of the presence of molecules in the device.     

激光功率对铜基粉末冶金摩擦材料微观组织及性能的影响

为提高铜基粉末冶金摩擦材料的综合性能指标,研究了宽带激光表面改性功率对摩擦材料微观组织及性能的影响.采用扫描电镜、X射线衍射仪对微观组织进行了表征,采用硬度计、摩擦磨损试验机等仪器对性能进行了测试.结果表明:在扫描速度150mm/min条件下,当激光功率低于1300W时,α-Cu的相对含量没有太大变动,随着激光功率的增加,摩擦材料中α-Cu聚合体边缘溶解加剧,大块聚合态α-Cu细小化,铜基粉末冶金层密度、硬度逐渐增加,耐磨性增强,摩擦系数提高.当激光功率超过1300W后,α-Cu的相对含量开始减少.α-Cu在有液相存在的条件下开始聚合生长变大.铜基粉末冶金层密度、硬度较快降低,磨损开始加剧,摩擦系数变大.     

Interfaces analysis by impedance spectroscopy and transient current spectroscopy on semiconducting polymers based metal–insulator–semiconductor capacitors

Impedance and transient current measurements on metal–insulator–semiconductor (MIS) capacitors are used as tools to thoroughly investigate the bulk and interface electronic transport properties of semiconducting polymers, i.e. poly(3-hexylthiophene) (P3HT). Distinct features were observed at both interfaces, i.e. metal–semiconductor and semiconductor–insulator. The results revealed a dispersive transport in the bulk due to the band tail of the localized states, presence of interface states at the interface between the insulator and the semiconductor and formation of a less conductive small layer at the interface semiconductor–metal contact due to intrusions of sputtered Au particles. Effects of self-assembled monolayers (SAMs) treatments of the gate insulating dielectric were investigated showing that treating the gate dielectric with either ozone or hexamethyldisilazane (HMDS) or octyltrichlorosilane (OTS) alter not only the interface semiconductor–insulator but the bulk properties as well. An exponential density of states with a width parameter of 38–58 meV depending on the surface treatment was found to be representative of the band tail of P3HT. Though both OTS and HMDS treatments slightly increase the density of interface states, only OTS treated samples showed a decrease in disorder parameter of the bulk. The latter fact can be attributed to an increase of the grain size due to a favored π-π stacking film growth. An outcome explaining the already reported increase of the lateral mobility and decrease of the vertical mobility observed upon OTS treatment of the gate insulating dielectric in poly(3-hexylthiophene) based devices.     

Direct investigations of the interface impedance of organic field-effect transistors with self-assembled-monolayer-modified electrodes

It has been demonstrated that the modification of electrodes with self-assembled monolayers (SAMs) reduces the contact resistance and improves the device performances of organic field-effect transistors (OFETs). However, it has been difficult to judge if the contact resistance was reduced by the change in the electronic properties or by the change in the morphology of the metal–organic interface caused by the SAM modification because they have been difficult to be separately assessed. We have directly investigated the local impedance and the potential difference at the electrode–channel interfaces of the OFETs with and without modification of the electrodes by a pentafluorobenzenethiol SAM using frequency-modulation scanning impedance microscopy (FM-SIM). The potential profile measurement and the FM-SIM measurement at the interface showed that the improvement of the field-effect mobility in the SAM-modified OFET was caused by the reduction of the energy level mismatch, namely, the hole injection barrier at the source–channel interface, presumably with the reduction of the hole trap sites at the source–channel interface.     

液晶玻盒结构中PI层摩擦定向的实现

液晶玻璃表面涂敷一层有机高分子薄膜,这层薄膜是液晶玻盒结构的一个重要组成部分,行业内称之为液晶玻盒定向层（PI层）。这层薄膜经过绒布类材料高速摩擦来实现定向,使玻盒内的液晶分子可以按照摩擦所产生的沟槽方向来实现想要达到的均匀有序排列。文章主要介绍了摩擦工艺实现的方法以及摩擦胶辊与摩擦布的设计与选用。