A Hybrid Continuum-Molecular Analysis of Interfacial Force Microscope Experiments on a Self-Assembled Monolayer

2004 ◽  
Vol 73 (5) ◽  
pp. 769-777 ◽  
Author(s):  
Mingji Wang ◽  
Kenneth M. Liechti ◽  
Vibha Srinivasan ◽  
John M. White ◽  
Peter J. Rossky ◽  
...  
Keyword(s):  
Cohesive Zone Model ◽  
Zone Model ◽  
Self Assembled Monolayer ◽  
Compressive Response ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Adhesive Interactions ◽  
Dynamics Simulations ◽  
Force Profiles ◽  
Interfacial Force

Nanoindentation experiments were performed on a defect-free, molecular self-assembled monolayer of octadecyltrichlorosilane (OTS) on silicon using an interfacial force microscope (IFM). The IFM provided repeatable and elastic force profiles corresponding to the adhesive and compressive response of these 2.5nm thick monolayers. As a first step in the analysis of the force profiles, the OTS was assumed to be linearly elastic and isotropic, and adhesive interactions were accounted for via a cohesive zone model. However, the assumption of linearity gave rise to force profiles that did not match the measurements. As a result, the mechanical behavior of the OTS was extracted from molecular-dynamics simulations and represented as a hypoelastic material, which, when used in finite element analyses of the IFM experiments, was able to fully reproduce the force profiles. This suggests that the continuum representation of the mechanical and adhesive behavior of self-assembled monolayers may be directly obtained from molecular analyses.

Laser Polishing of Cold Work Steel AISI D2 for Dry Metal Forming Tools: Surface Homogenization, Refinement and Preparation for Self-Assembled Monolayers

2018 ◽  
Vol 767 ◽  
pp. 69-76 ◽  
Author(s):  
Ingo Ross ◽  
André Temmler ◽  
Moritz Küpper ◽  
Stephan Prünte ◽  
Marco Teller ◽  
...  
Keyword(s):  
Cold Extrusion ◽  
Self Assembled Monolayers ◽  
Homogeneous Distribution ◽  
Self Assembled Monolayer ◽  
Pulsed Laser Radiation ◽  
Laser Polishing ◽  
Assembled Monolayers ◽  
Aisi D2 ◽  
Self Assembled ◽  
Forming Tools

Liquid lubrication guarantees high precision and surface quality of workpieces in industrial forming processes. In the case of aluminum cold extrusion, wear and cold welding due to direct contact of tool and workpiece are usually prevented by the extensive use of lubricants. Since the use of lubricants is economically and ecologically unfavorable, surface treatments of tools by, e.g. laser polishing and/or coatings are in the focus of current investigations to substitute these lubricants and establish so called “dry metal forming” processes. The material AISI D2, a ledeburitic 12% chromium steel which is known to have a significant amount of chromium carbide precipitations, is widely used in cold extrusion for forming tools. The large fraction of chromium carbide precipitations, however, hinder the formation of a dense self-assembled monolayer (SAM) that is necessary to avoid direct contact of reactive aluminum with surface oxides of the tool. Therefore, a homogeneous distribution of the chemical elements with a smaller fraction or no chromium carbides in the steel matrix, particularly in the tool surface, is aimed for. Using laser polishing, the surface layer is molten by continuous or pulsed laser radiation. Within the melt pool, the elementary distribution is homogenized as a result of thermal convection and diffusion processes, as well as a smoothed surface and a grain refinement are achieved. Consequently, the effects of the surface treatment by laser polishing on the area coverage of self-assembled monolayers are investigated. Thus, a combined surface treatment by laser polishing and functionalization with a dense self-assembled monolayer shall reduce overall adhesive wear. For this investigation, several specimens of conventional manufactured and powder metallurgical molten AISI D2 are laser polished using continuous or pulsed laser radiation or a combination of both. The resulting surfaces are investigated by microscopy and spectroscopic techniques to analyze the surface topography and the elemental distribution near to the surface. These results are compared to those of conventionally hand-polished specimens. Furthermore, the influence of the element homogenization and grain refinement on the area coverage of self-assembled monolayers is explored. First results show that laser polishing of AISI D2 is suitable to achieve a reduction of grain size and a more homogeneous distribution of chromium carbides within the surface layer.

Spectral and cyclic voltammetric characterization of self-assembled monolayers on gold of pyrene end-labeled oligonucleotide duplexes

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1077-1084 ◽  
Author(s):  
R Scott Reese ◽  
Marye Anne Fox
Keyword(s):  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Self Assembled Monolayer ◽  
Surface Emission ◽  
Assembled Monolayers ◽  
Oligonucleotide Duplex ◽  
Self Assembled ◽  
Duplex Formation

Self-assembled monolayers of sulfur-terminated oligonucleotide duplexes were formed on flat gold surfaces, either by exposure of a self-assembled monolayer bearing one oligonucleotide strand to the complementary strand or by preformation of a oligonucleotide duplex that was then deposited on a fresh gold surface. Virtually identical spectral behavior was observed whether the duplex was produced before deposition or by in situ complementary association. With a duplex bearing an appropriate pyrene end-label, the resulting thin film was photoresponsive. Surface emission measurements show no evidence for pyrene aggregation on the modified surfaces. The polarity of the photocurrent, reflecting photoinduced electron transfer initiated by photoexcitation of pyrene, is opposite that expected from the oligonucleotide-mediated reduction of the appended pyrene excited state.Key words: oligonucleotide, self-assembled monolayer, duplex formation, photoelectrochemistry, surface emission.

Self-Assembled Monolayers of 12-Mercaptododecylphosphonic Acid on Titania Particles; Application to the Extraction of Heavy Metals

2004 ◽  
Vol 847 ◽  
Author(s):  
Sébastien Anthérieu ◽  
Florence Brodard-Séverac ◽  
Gilles Guerrero ◽  
P. Hubert Mutin
Keyword(s):  
Heavy Metals ◽  
Chemical Analysis ◽  
Phosphonic Acid ◽  
Metal Extraction ◽  
Self Assembled Monolayers ◽  
Extraction Ability ◽  
Self Assembled Monolayer ◽  
Inorganic Hybrid ◽  
Assembled Monolayers ◽  
Self Assembled

ABSTRACTTitania particles (P25 DEGUSSA AG) were treated by a solution of 12-mercaptododecyl-phosphonic acid (MDPA) in toluene to obtain an organic-inorganic hybrid material with thiol functions at the surface. This material was characterized by chemical analysis, solid state 31P MAS NMR and FTIR spectroscopies, and XPS. Reaction of the phosphonic acid end of MDPA with the TiO2 surface led to the formation of a relatively dense and well-ordered self-assembled monolayer (SAM), with a density of about 3.9 SH functions per nm2. This material was tested for the extraction of mercury in water at pH 7, 9, and 11. Chemical analysis indicated no loss of SH functionality, even at pH 11. The best extraction results were obtained at pH 9 and 11, with a metal extraction ability between 85 and 90%.

Specific Immobilization of Streptavidin on Mixed Self-Assembled Monolayers as Mixing Ratio

2007 ◽  
Vol 121-123 ◽  
pp. 495-498 ◽  
Author(s):  
Jun Hyung Park ◽  
Buyng Su Park ◽  
Gu Huh ◽  
Seung Hyun Lee ◽  
Hyun Sook Lee ◽  
...  
Keyword(s):  
Colorimetric Detection ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Local Domain ◽  
Mixing Ratio ◽  
Tunneling Microscopy ◽  
Self Assembled Monolayer ◽  
Assembled Monolayers ◽  
Self Assembled

We report on the distribution of mixed self-assembled monolayers (SAMs) composed of biotinylated and diluent alkylthiolates for streptavidin immobilization. Two thiol derivatives, 11-mercapto-1-undecanol (MUOH) and 11-mercaptoundecanoic-(8-biotinylamido-3,6-dioxaoctyl) amide (MBDA), were employed for mixed SAM. These thiols formed self-assembled monolayer without local domain, and streptavidins were immobilized onto biotinylated gold surface without nonspecific binding. In order to find the optimized condition of immobilization of streptavidin, we controlled the mixing ratio of two kind thiols by colorimetric detection assay, and the immobilization was characterized by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and ellipsometer.

Comparison of Proliferation and Growth of Human Keratinocytes on Plasma CO-Polymers of Acrylic acid/1,7- Octadiene and Self Assembled Monolayers

1998 ◽  
Vol 544 ◽  
Author(s):  
D. B. Haddow ◽  
R. M. France ◽  
R. D. Short ◽  
S. Macneil ◽  
R. A. Dawson
Keyword(s):  
Cell Proliferation ◽  
Tissue Culture ◽  
Carboxylic Acid ◽  
Cell Attachment ◽  
Human Keratinocytes ◽  
Collagen I ◽  
Self Assembled Monolayers ◽  
Self Assembled Monolayer ◽  
Assembled Monolayers ◽  
Self Assembled

AbstractHuman keratinocytes have been cultured on plasma co-polymers (PCPs), self assembled monolayers (SAMs), tissue culture poly(styrene) (TCPS) and collagen I. The degree of keratinocyte attachment was measured over 24 hours and cell proliferation and growth monitored over 7 days using optical microscopy and DNA concentrations. Cell attachment and proliferation and growth on the PCP surfaces were compared with 2 self assembled monolayer (SAM) systems. PCP surfaces containing carboxylic acid functionalities promoted keratinocyte attachment, with optimum attachment levels seen on surfaces containing less than 5% acid groups. The level of attachment on these surfaces was comparable to that seen on collagen I, a preferred substratum for the culturing of keratinocytes. After several days in culture the cells were well attached and proliferative. Keratinocytes attached well to acidterminated SAMs but attached poorly to methyl-terminated SAMs.

Molecular Dynamics Simulation Based Cohesive Zone Representation of Intergranular Fracture Processes in Bicrystalline Graphene

2020 ◽  
Author(s):  
MD Imrul Reza Shishir ◽  
Alireza Tabarraei
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundaries ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Dynamics Simulation ◽  
Zone Model ◽  
Zone Method ◽  
Simulation Based ◽  
Dynamics Simulations ◽  
Fracture Processes

Abstract The fracture properties of various grain boundaries in graphene are investigated using the cohesive zone method (CZM). Molecular dynamics simulations are conducted using REBO2+S potential in order to develop a cohesive zone model for graphene grain boundaries using a double cantilever bicrystalline graphene sheet. The cohesive zone model is used to investigate the traction–separation law to understand the separation-work and strength of grain boundaries.

Molecular Dynamics Study of Interfacial Thermal Resistance of Mercapto-Alkanol Self-Assembled Monolayer and Water

2009 ◽  
Author(s):  
Touru Kawaguchi ◽  
Gota Kikugawa ◽  
Ikuya Kinefuchi ◽  
Taku Ohara ◽  
Shinichi Yatuzuka ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Thermal Resistance ◽  
Chem Phys ◽  
Nonequilibrium Molecular Dynamics ◽  
Interfacial Thermal Resistance ◽  
Water Molecules ◽  
Self Assembled Monolayer ◽  
Self Assembled ◽  
Dynamics Simulations

The interfacial thermal resistance of 11-mercaptoundecanol (-S(CH2)11OH) self-assembled monolayer (SAM) adsorbed on Au(111) substrate and water was investigated using nonequilibrium molecular dynamics simulations. The interfacial thermal resistance was found to be a half of that in the system which consists of 1-dodecanthiol (-S(CH2)11CH3) SAM adsorbed on Au(111) and toluene [Kikugawa G. et al., J. Chem. Phys. (2009)]. The effective thermal energy transfer originates from hydrogen-bond structure between the SAM and water molecules in spite of weak structurization of water molecules near the SAM surface.

Coating a DNA self-assembled monolayer with a metal organic framework-based exoskeleton for improved sensing performance

The Analyst ◽  
2019 ◽  
Vol 144 (11) ◽  
pp. 3539-3545 ◽  
Author(s):  
Jiehua Ma ◽  
Wenxin Chai ◽  
Jianyang Lu ◽  
Tian Tian ◽  
Shuai Wu ◽  
...  
Keyword(s):  
Metal Organic Framework ◽  
Self Assembled Monolayers ◽  
Self Assembled Monolayer ◽  
New Strategy ◽  
Assembled Monolayers ◽  
Metal Organic ◽  
Self Assembled ◽  
Poor Stability ◽  
Sensing Performance ◽  
Organic Framework

The relatively poor stability of DNA self-assembled monolayers (SAMs) greatly limits their use in real applications. A new strategy is reported to protect the DNA SAMs by using a metal organic framework (MOF)-based exoskeleton.

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