Skip to main content

NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Isostructural Self-Assembled Monolayers, Part 1. Octadecyl 1-thiaoligo(ethylene oxides)

Published

Author(s)

David J. Vanderah, Richard S. Gates, Vitalii I. Silin, D N. Zeiger, John T. Woodward IV, Curtis W. Meuse, Gintaras Valincius, B Nickel

Abstract

The self-assembled monolayers (SAMs) of a series of octadecyl 1-thiaoligo(ethylene oxide)x disulfides {[S(CH2CH2O)xC18H37]2}, where x = 4 to 8, were assembled on gold and characterized by reflection-adsorption infrared spectroscopy (RAIRS), spectroscopic ellipsometry (SE), and electrochemical impedance spectroscopy (EIS). Our results show that the SAMs differ over this range of x with an isostructural subset for x = 6 to 8. For x = 6 to 8, the RAIRS data shows that the 1-thiaoligo(ethylene oxide) [TOEO] segments adopt the ordered 7/2 helical conformation of the folded-chain crystal polymorph of poly(ethylene oxide) [PEO], oriented normal to the substrate, and the hydrocarbon segments adopt a nearly all-trans conformation tilted {approximately equal to} 30 degrees to the normal. The EIS data indicate highly stable, highly ordered, nearly defect-free SAMs that behave as ideal capacitors in an electrochemical environment. These SAMs may be described as highly uniform, nearly impervious films each composed of a single structural phase with the TOEO segment as described above and few domain boundaries or defects. As a result, SAM thicknesses should increase in a predictable fashion. SE calculations indicate SAM thickness increases by 0.30 0.02 nm/ethylene oxide (EO) unit for x = 6 to 8 in good agreement with the predicted {approximately equal to} 0.28 nm/EO unit from the unit cell dimensions of crystalline PEO. The absolute and relative thicknesses of these isostructural SAMs may be useful for a variety of surface science techniques.
Citation
Langmuir
Volume
19
Issue
7

Keywords

electrochemical impedance spectroscopy, infrared spectroscopy, self-assembled monolayers, spectroscopic ellipsometry, standard films

Citation

Ross, D. , Gates, R. , Silin, V. , Zeiger, D. , Woodward, J. , Meuse, C. , Valincius, G. and Nickel, B. (2003), Isostructural Self-Assembled Monolayers, Part 1. Octadecyl 1-thiaoligo(ethylene oxides), Langmuir (Accessed October 11, 2025)

Issues

If you have any questions about this publication or are having problems accessing it, please contact [email protected].

Created April 1, 2003, Updated February 19, 2017
Was this page helpful?