共查询到20条相似文献,搜索用时 15 毫秒
1.
Bernhard Basnar Martin Madera Gernot Friedbacher Thomas Vallant Ulrich Mayer Helmuth Hoffmann 《Mikrochimica acta》2000,133(1-4):325-329
We describe a new method for 3 dimensional nanostructuring on silicon surfaces using self-assembled monolayers. Partial multilayers
were formed by repeated deposition of trichlorosilylheptadecanoic acid methyl ester (TSHEME) and subsequent reduction to yield
a hydroxylic surface. These structures were afterwards oxidised using UV/ozone, yielding silicon oxide features. In this way
both organic multilayered structures as well as ones comprised of silicon oxide have been produced with precise control of
the height and invariant lateral shape of these structures. We have tried to apply samples prepared in this fashion to the
calibration of AFM-scanners in vertical direction. Due to height artefacts caused by the tip-sample interaction a general
calibration is not possible on the molecular scale.
However, the structures produced can be used as model systems for the investigation of various sources of height artefacts
and also for calibration purposes as long as samples with similar chemical and mechanical properties are to be investigated. 相似文献
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Gold-coated atomic force microscope (AFM) tips functionalized with amine-, hydroxyl-, carboxylic acid-, and methyl-terminated alkanethiol molecules were used to probe the adhesive forces of polystyrene and poly(acrylic acid) films in dry air (relative humidity < 0.5%). X-ray photoelectron spectroscopy (XPS) and contact angle measurements confirmed the quality and uniformity of similarly treated gold surfaces and the polymer films. XPS indicated that the amine-functionalized thiol films were protonated and comprised of multilayers. Contact angle data were used to calculate surface free energies, and DMT theory yielded the works of adhesion and interfacial free energies for the tip-substrate combinations. In the case of polystyrene, the work of adhesion followed the order methyl > carboxylic acid > hydroxyl > amine. For poly(acrylic acid), the observed order was hydroxyl > amine > carboxylic acid > methyl. 相似文献
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Ma L Jia M Hu J Ouyang J Na N 《Journal of the American Society for Mass Spectrometry》2012,23(7):1271-1278
We describe direct analysis of self-assembled monolayers (SAMs) on copper surfaces by low temperature plasma (LTP) mass spectroscopy (MS). Two kinds of SAMs formed from n-dodecylmercaptan (NDM) and l-phenyl-5-mercaptotetrazole (PMTA) were prepared on copper by spontaneous chemisorption. With the LTP probe, desorption and ionization of the SAMs was easily achieved, and the ions produced were introduced into MS for analysis. Characteristic fragment ions from NDM SAMs, mainly [M + M - H](+) (M is the NDM molecule) and from PMTA SAMs, mainly [M + H - S](+) (M is the PMTA molecule), were both absent in the MS spectra of neat NDM and PMTA samples. This provided evidence of the formation of SAMs on copper. As a supplementary method, LTP-MS is helpful in obtaining information on the barrier properties of SAMs on copper, such as inhibitor efficiency (IE) and the surface adsorption concentration of corrosive electrolyte (Γ*) surrounding copper. Aiming for an evaluation of the reliability of LTP-MS, a comparative study of our method and the traditional method of cyclic voltammetry (CV) showed a correlation coefficient higher than 0.97. In addition, a rough, simple procedure for imaging of the distribution of the molecules adsorbed on copper surface was presented. The study supplied a rapid and simple method for direct investigation of SAMs on copper. 相似文献
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Franz Effenberger Günther Gtz Bernd Bidlingmaier Markus Wezstein 《Angewandte Chemie (International ed. in English)》1998,37(18):2462-2464
Direct lateral patterning in the formation of self-assembled monolayers (SAMs) on silicon was achieved by the photoinduced reaction of aldehydes with Si(111)-H surfaces by using the usual masking techniques (see the schematic illustration; on the right-hand side is a microscopy image of a patterned SAM formed from octadecanal). 相似文献
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Adhesive and frictional forces between surfaces modified with self-assembled monolayers (SAMs) and immersed in solvents were measured with chemical force microscopy as functions of surface functionality and solvent. Si/SiO2 substrates were modified with SAMs of alkylsiloxanes (SiCl3(CH2)n-X), and gold-coated AFM tips were modified with SAMs of alkylthiolates (HS-(CH2)n-X). SAMs of alkylsiloxanes terminated in a methyl or oxidized vinyl group; SAMs of alkanethiolates terminated in a methyl or carboxyl group. Adhesive and frictional forces were measured in hexadecane, ethanol, 1,2-propanediol, 1,3-propanediol, and water. The work of adhesion (W) was calculated with the Johnson-Kendall-Roberts theory of adhesive contact. The JKR values agreed well with values derived from the Fowkes-van Oss-Chaudhury-Good surface tension model and from contact angle results. Calculated values of W for all combinations of contacting surfaces and solvents spanned two orders of magnitude. W correlated with the surface tension of the solvent for hydrophobic/hydrophobic interactions; hydrophilic/hydrophilic and hydrophobic/hydrophilic interactions were more complex. Friction forces were fit to a modified form of Amonton's law. For any solvent, friction coefficients were largest for the hydrophilic/hydrophilic contacting surfaces. The friction coefficient for any contacting pair was largest in hexadecane. In polar solvents, friction coefficients scaled with solvent polarity only for hydrophobic/hydrophobic contacting pairs. Copyright 1999 Academic Press. 相似文献
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Christoph D. Hahn Ali Tinazli Martin Hölzl Christa Leitner Filip Frederix Bernd Lackner Norbert Müller Christian Klampfl Robert Tampé Hermann J. Gruber 《Monatshefte für Chemie / Chemical Monthly》2007,138(3):245-252
Summary. The present study describes new synthetic routes to oligo(ethylene glycol)-terminated alkanethiols (OEG-ATs), starting from α,ω-dibromoalkanes, which are reacted either with OEG or with trityl mercaptan in the first step. In addition to these ether conjugates of OEG and AT, analogous ester and amide conjugates were prepared by established procedures. All thiols were used to form self-assembled
monolayers (SAMs) on cleaned gold surfaces and these were stored for 1–2 weeks under water at 4°C before the extent of nonspecific protein
adsorption was tested with IgG, BSA, and lysozyme at 1 mg cm−3 protein concentration in phosphate-buffered saline. Under these practice-oriented testing conditions, SAMs with tri(ethylene glycol) chains (EG
3) exhibited nonsatisfactory protein resistance, in sharp contrast to EG
4 or longer OEG chains. The effectiveness of EG
3 was partially restored when they were linked to a long acyl chain (16-mercaptohexadecanoic acid) instead of 12-mercaptododecane
or 11-mercaptoundecane. Furthermore it was found that (i) SAM formation at 20 μM thiol versus 500 μM
OEG-AT gave identical results, (ii) gel-filtered proteins were much less adsorbed than the unpurified commercial products, and (iii)
the method for gold-precleaning was very critical. In conclusion, this study offers convenient synthetic routes to OEG-AT and helps to choose molecules and procedures for reliable preparation of protein-resitant SAMs with prolonged stability during storage. 相似文献
8.
Christoph D. Hahn Ali Tinazli Martin H?lzl Christa Leitner Filip Frederix Bernd Lackner Norbert Müller Christian Klampfl Robert Tampé Hermann J. Gruber 《Monatshefte für Chemie / Chemical Monthly》2007,398(4):245-252
The present study describes new synthetic routes to oligo(ethylene glycol)-terminated alkanethiols (OEG-ATs), starting from α,ω-dibromoalkanes, which are reacted either with OEG or with trityl mercaptan in the first step. In addition to these ether conjugates of OEG and AT, analogous ester and amide conjugates were prepared by established procedures. All thiols were used to form self-assembled
monolayers (SAMs) on cleaned gold surfaces and these were stored for 1–2 weeks under water at 4°C before the extent of nonspecific protein
adsorption was tested with IgG, BSA, and lysozyme at 1 mg cm−3 protein concentration in phosphate-buffered saline. Under these practice-oriented testing conditions, SAMs with tri(ethylene glycol) chains (EG
3) exhibited nonsatisfactory protein resistance, in sharp contrast to EG
4 or longer OEG chains. The effectiveness of EG
3 was partially restored when they were linked to a long acyl chain (16-mercaptohexadecanoic acid) instead of 12-mercaptododecane
or 11-mercaptoundecane. Furthermore it was found that (i) SAM formation at 20 μM thiol versus 500 μM
OEG-AT gave identical results, (ii) gel-filtered proteins were much less adsorbed than the unpurified commercial products, and (iii)
the method for gold-precleaning was very critical. In conclusion, this study offers convenient synthetic routes to OEG-AT and helps to choose molecules and procedures for reliable preparation of protein-resitant SAMs with prolonged stability during storage. 相似文献
9.
CHEN Shao-Wei 《高等学校化学学报》2000,21(Z1):362
Electrochemical studies of the self-assembled monolayers of gold nanoparticles were reported. The particle surface assemblies were constructed by using surface-active particle molecules where multiple copies of peripheral thiol groups were introduced via exchange reactions with alkanedithiols[1,2]. Excessive dithiol and displaced thiol ligands were removed from the cluster exchange solution by liquid extraction using a hexane-methanol system. The resulting particle adlayers exhibited discrete electron-transfer features that were ascribed to the quantized capacitance charging to the particle double layers. The electrode double-layer capacitance, evaluated from impedance measurements, also showed a modulation with electrode potentials. Consistent electron-transfer rate constants were obtained from the Laviron evaluation as well as from the impedance measurements[1].In particular, in aqueous solutions, in the presence of certain hydrophobic electrolyte ions, the discrete charging was rectified depending on the electrode[2]. 相似文献
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通过液相沉积在云母表面制备1H, 1H, 2H, 2H-全氟癸基三氯硅烷(FDTS)自组装单分子膜(SAMs)。室温下,将1.0 mmol·L-1的FDTS溶液静置水解15 min,再把云母浸入自组装30 min,原子力显微镜(AFM)表征发现,液相沉积过程中FDTS的团聚现象得到有效解决。该方法制备出了高覆盖率(85% ± 2%)和低均方根粗糙度(0.58 nm)的FDTS SAMs,且单分子膜的生长过程符合Langmuir一级动力学吸附模型。在液相沉积过程中,若水解和组装同时进行,过长的水解时间(大于30 min)或组装时间(大于30 min)均会导致FDTS的团聚,进而极大降低SAMs的质量。 相似文献
15.
Einav Amit Iris Berg Dr. Elad Gross 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(57):13046-13052
N-heterocyclic carbenes (NHCs) have emerged as a unique molecular platform for the formation of self-assembled monolayers (SAMs) on various surfaces. However, active carbene formation requires deprotonation of imidazolium salt precursors, which is mostly facilitated by exposure of the salt to exogenous base. Base residues were found to be adsorbed on the metal surface and hindered the formation of well-ordered carbene-based monolayers. Herein, we show that nitron, a triazolone-based compound that freely tautomerizes to a carbene, can spontaneously self-assemble into monolayers on Pt and Au surfaces, which obviates the necessity for base-induced deprotonation for active carbene formation. SAMs of nitron were found to be thermally stable and could not be displaced by thiols, and thus their high chemical stability was demonstrated. The amino group in surface-anchored nitron was shown to be chemically available for SN2 reactions, and makes surface-anchored nitron a chemically addressable cross-linking reagent for surface modifications. 相似文献
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基于卟啉化合物良好的光电性能,结合自组装膜技术,对其信息存储进行了研究.卟啉分子单体的结构、自组装膜表面卟啉的空间定位以及自组装膜基底材料的选择等对卟啉的信息存储产生着重要影响.目前,卟啉自组装膜的信息存储研究已由单点存储向超高密度多点存储发展. 相似文献
18.
The electrochemical behavior of an azobenzene containing self-assembled monolayer (SAM) has been examined by means of in-situ Fourier transform infrared reflection absorption (FTIRRA) spectroscopy. The electrochemical reduction product of azobenzene has been confirmed to be hydrazobenzene. A stable and reversible process in both electrochemistry and architecture has been found in the monolayer film. 相似文献
19.
An investigation is presented of the interaction of charged self-assembled monolayers (SAMs) with a monoprotic ionizable acid functional group (-COOH) and uncharged SAMs with a methyl terminated functional group (-CH(3)). The strength of the interactions are determined using an atomic force microscope. For all electrolyte conditions investigated the interactions are not well described by a summation of van der Waals attractions and electrostatic repulsions in a manner suggesting that van der Waals attractions are screened. The repulsions are accurately described as corresponding to two surfaces of different charge interacting with surface charges that are independent of separation (i.e., the constant charge model). A small adhesion force was observed under all conditions and its magnitude increased with NaCl concentration. Copyright 2000 Academic Press. 相似文献