Assesment of Vibrational Coupling at Solid-SAM Junctions

2011 ◽  
Author(s):  
Christopher B. Saltonstall ◽  
John C. Duda ◽  
Patrick E. Hopkins ◽  
Pamela M. Norris
Keyword(s):  
Thermal Conductance ◽  
Chemical Properties ◽  
Self Assembled Monolayers ◽  
Vibrational Coupling ◽  
Thermal Boundary Conductance ◽  
Hartree Fock ◽  
Assembled Monolayers ◽  
Methylene Groups ◽  
Methylene Group ◽  
And Chemical Properties

Self-assembled monolayers (SAMs) have recently garnered much interest due to their unique electrical and chemical properties. The limited literature detailing SAM thermal properties has suggested that thermal boundary conductance (TBC) at solid-SAM junctions is not only low, but also insensitive to changes in SAM length as the number of methylene groups (-CH2-) along alkanedithiol chains is varied from 8 to 10. The present study investigates the vibrational spectra of alkanedithiol SAMs as a function of the number of methylene groups forming the molecule backbone via Hartree-Fock methods and the subsequent effects on TBC calculated using a diffuse scattering model. In particular, the vibrational overlap between the alkanedithiol and Au is studied. It is found that despite the addition of 9 new vibrational modes per added methylene group, only one of those modes is elastically accessible to Au. It is believed that this “vibrational inaccessibility” is the cause of the insensitivity of thermal conductance to molecule length.

scholarly journals Monte Carlo analysis of frequency domain thermoreflectance data for quantitative measurement of interfacial thermal conductance at solid-liquid interfaces modified with self-assembled monolayers

2021 ◽  
Vol 2116 (1) ◽  
pp. 012042
Author(s):  
Kenny Yu ◽  
Ryan Enright ◽  
David McCloskey
Keyword(s):  
Monte Carlo ◽  
Thermal Conductance ◽  
Work Of Adhesion ◽  
Self Assembled Monolayers ◽  
Liquid Interfaces ◽  
Confidence Bounds ◽  
Interfacial Thermal Conductance ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Solid Liquid

Abstract A Monte Carlo method, implemented for quantifying confidence bounds on thermoreflectance (TR) measurements of interfacial thermal conductance G at solid-liquid interfaces modified with self-assembled monolayers (SAMs) is presented in this paper. Here we used 1-decanethiol (1DT) and 1H,1H,2H,2H-Perfluorodecanethiol (PFDT) SAMs to achieve two distinct work of adhesion. Using TR measurements in conjunction with Monte Carlo simulations, we determined G values to be 51 ± 7 MWm-2K-1, 58 ± 8 MWm-2K-1, and 72 ± 17 MWm-2K-1 for Au-PFDT-H2O, Au-1DT-H2O, and Au-H2O, respectively. Our results with the new confidence bounds position our experimental data on surfaces modified with SAMs comparable to literature. However, contrary to previous results shown in the literature, our data showed that a significant decrease in G can be seen for DI water on bare Au that was exposed in ambient for extended period. Our results indicate that G could be influenced by factors beyond a simple work of adhesion, an indication also seen from the work of Park et al.. To solidify this finding, further investigation is necessary to better understand G dependence on surface wettability.

Room temperature thermal conductance of alkanedithiol self-assembled monolayers

2006 ◽  
Vol 89 (17) ◽  
pp. 173113 ◽  
Author(s):  
Robert Y. Wang ◽  
Rachel A. Segalman ◽  
Arun Majumdar
Keyword(s):  
Room Temperature ◽  
Thermal Conductance ◽  
Self Assembled Monolayers ◽  
Assembled Monolayers ◽  
Self Assembled

Preparation of Azobenzenealkanethiols for Self-Assembled Monolayers with Photoswitchable Properties

2010 ◽  
Vol 63 (2) ◽  
pp. 303 ◽  
Author(s):  
Simone Krakert ◽  
Andreas Terfort
Keyword(s):  
Oxygen Atom ◽  
Hybrid Systems ◽  
Self Assembly ◽  
Alkyl Chain ◽  
The Self ◽  
Self Assembled Monolayers ◽  
Assembled Monolayers ◽  
Methylene Groups ◽  
Broad Variety ◽  
Fast Access

A series of azobenzenealkanethiol compounds with the structure p-RC6H4N=NC6H4(CH2)nSH (n = 3, 4) was synthesized using a divergent strategy with the two anilines H2NC6H4(CH2)nSAc as central compounds. This strategy provides fast access to a broad variety of the respective azobenzenethiols without (note!) an oxygen atom in the alkyl chain, thus permitting the self-assembly of these compounds onto gold in a predictable conformation, also taking advantage of the previously found odd–even effect in aromatic–aliphatic hybrid systems. Initial experiments indicate that all of these molecules indeed form dense monolayers, in which the orientation of the azobenzene unit is determined by the number of methylene groups in the aliphatic part of the molecules.

scholarly journals Theoretical Prediction of Possible Drug Treatment of COVID-19 using Coumarins Containing Chloroquine Moeity

2020 ◽  
Vol 32 (12) ◽  
pp. 3120-3126
Author(s):  
A.A. Ibrahim ◽  
O.M. Yahya ◽  
M.A. Ibrahim
Keyword(s):  
Theoretical Calculations ◽  
Chemical Properties ◽  
Basis Sets ◽  
Am1 Method ◽  
Hartree Fock ◽  
Physico Chemical ◽  
Coumarin Compound ◽  
Semi Empirical ◽  
Physical And Chemical ◽  
And Chemical Properties

Chloroquine was theoretically reacted with the coumarin compound. Two compounds viz. [N-(7-chloroquinolin-4-yl)-N-(5-(diethylamino)-pentan-2-yl)-4-methyl-2-oxo-2H-chromene-7- sulfonamide] (3) and [N-(7-chloroquinolin-4-yl)-N-(5-(diethylamino)pentan-2-yl)-4-methyl-2-oxo- 2H-chromene-6-sulfonamide] (4) were suggested. The results showed that compound 4 may influence the COVID-19 treatment. The physico-chemical parameters were determined through theoretical calculations by using Hartree-Fock at different basis sets (6-31G), (STO/3G) and the semi-empirical (AM1) method. The calculations demonstrated the scheme of reaction between coumarin and the chloroquine structure by using the predicted mechanisms. The physical and chemical properties of the predicted compounds were determined to select the optimal form as the candidate for COVID-19 treatment. Compound 4 was more stable than compound 3, with different proteins viz. 6YHU, 6YI3 and 6LU7. Three types of software, including Gaussian 03, Chem-Bio office and molecular operating environment (MOE) were employed.

Tribology of PFPE Overcoated Self-Assembled Monolayers Deposited on Silicon Surface: Effect of Thermal Treatment

2005 ◽  
Author(s):  
N. Satyanarayana ◽  
S. K. Sinha
Keyword(s):  
Thermal Treatment ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Surface Effect ◽  
Chemical Properties ◽  
Dip Coating ◽  
Self Assembled Monolayers ◽  
Wear Life ◽  
Assembled Monolayers ◽  
Self Assembled

Effect of thermal treatment on the friction and wear of monomolecular layers of SAMs (Self-assembled monolayers) overcoated with PFPE was studied using ball-on-disk tribometer. Two SAMs, Octadecyltrichlorosilane (OTS) and 3-aminopropyltrimethoxysilane (APTMS) were formed on the Si substrate by self-assembly followed by dip-coating with perfluoropolyether (PFPE). Modified Si samples are thermally treated at 150 °C under vacuum for 2h. The physical and chemical properties of modified samples, before and after thermal treatment, are analyzed using contact angle measurements, X-ray photoelectron spectroscopy (XPS). Tribological properties are evaluated using Universal Micro Tribometer (UMT). A Si3N4 ball of 4mm diameter is used as the counterface. Thermal treatment of the PFPE coated SAMs and Si surface reduced the coefficient of friction to slightly lower values in all cases. Thermal treatment has shown slight increase in wear life in the case of PFPE coated APTMS SAM surfaces whereas it decreased the wear life in the case of PFPE coated OTS SAM and Si surfaces. The exact reasons for this behavior are not clear at present, but it is being speculated that thermal treatment effects the extent of bonding between the surface groups of PFPE and SAMs and mobile characteristics of the PFPE, which finally influence the wear durability characteristics. Therefore, the differences in the wear durability characteristics are analyzed using changes in the surface energies and the amount of strongly adsorbed PFPE, as a result of thermal treatment.

Thermal conductance in single molecules and self-assembled monolayers: physicochemical insights, progress, and challenges

2020 ◽  
Vol 8 (38) ◽  
pp. 19746-19767
Author(s):  
Sohyun Park ◽  
Jiung Jang ◽  
Hojin Kim ◽  
Dong Il Park ◽  
Kyeongtae Kim ◽  
...  
Keyword(s):  
Thermal Transport ◽  
Single Molecules ◽  
Thermal Conductance ◽  
Molecular Junctions ◽  
Self Assembled Monolayers ◽  
Recent Advances ◽  
Assembled Monolayers ◽  
Self Assembled

Recent advances in the physicochemical understanding of thermal transport across molecular junctions of single molecules and monolayers are discussed.

scholarly journals Effects of Surface Chemical Properties on the Frictional Properties of Self-Assembled Monolayers Lubricated with Oleic Acid

2012 ◽  
Vol 7 (4) ◽  
pp. 218-224 ◽  
Author(s):  
Koji Miyake ◽  
Takamasa Kume ◽  
Miki Nakano ◽  
Atsushi Korenaga ◽  
Koji Takiwatari ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Chemical Properties ◽  
Self Assembled Monolayers ◽  
Surface Chemical ◽  
Frictional Properties ◽  
Assembled Monolayers ◽  
Self Assembled

scholarly journals THE APPLICATION OF GOLD SURFACES AND PARTICLES IN NANOTECHNOLOGY

2006 ◽  
Vol 13 (02n03) ◽  
pp. 297-307 ◽  
Author(s):  
M. J. FORD ◽  
C. MASENS ◽  
M. B. CORTIE
Keyword(s):  
Density Functional ◽  
Chemical Properties ◽  
Self Assembled Monolayers ◽  
Hydrogen Atoms ◽  
Gold Surfaces ◽  
Selective Functionalization ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Computational Predictions ◽  
Effect Of Surface

Gold is widely used in nanotechnology, for example as a substrate in forming self-assembled monolayers or as nanoparticles for their unique optical and chemical properties. In this paper we give an overview of the properties of gold relevant to its potential application in molecular-scale devices and present some of our recent computational predictions. Density functional calculations of molecular adsorption onto gold surfaces were used to investigate the effect of surface symmetry and identify new linking schemes for self-assembled monolayers. Adsorption energies of methylthiolate (SCH3) onto the (111), (100) and (110) surfaces of gold are predicted to be 39.3, 48.4 and 51.1 kcal/mol respectively and demonstrate that selective functionalization of the surfaces is possible. Phosphine molecules with at least two hydrogen atoms substituted for methyl groups are predicted to form Au – P surface bonds with energies of about 13–20 kcal/mol.

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