Molecular-level approach to inhibit degradations of alkanethiol self-assembled monolayers in aqueous media

Guohua Yang, Nabil A. Amro, Zane B. Starkewolfe, Gang-yu Liu

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

A molecular-level approach is developed to prevent or inhibit the degradation processes of alkanethiol self-assembled monolayers (SAMs). Previous studies revealed two degradation pathways: direct desorption and oxidation-desorption. By use of scanning tunneling microscopy (STM) and atomic force microscopy (AFM), in situ and time-dependent imaging reveals and confirms that degradations of alkanethiol SAMs on gold mainly initiate at defect sites, such as domain boundaries and vacancy islands, and then propagate into the ordered domains. Our approach targets at attaching small molecules with preferred adhesion to the defects. The best candidates are aqueous media containing a small amount of amphiphilic surfactant molecules, such as N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO). High-resolution studies demonstrate that DMSO and DMF molecules attach to SAM surfaces and more favorably at defect sites, forming relatively stable adsorbates. This attachment increases the activation energy sufficiently to inhibit both degradation pathways. The robustness of this approach has been investigated as a function of surfactant concentration, solution temperature, and the stirring condition. Molecular-level mechanisms and energetics for degradation inhibition of SAMs are also discussed in detail.

Original languageEnglish (US)
Pages (from-to)3995-4003
Number of pages9
JournalLangmuir
Volume20
Issue number10
DOIs
StatePublished - May 11 2004

Fingerprint

Self assembled monolayers
degradation
Degradation
Dimethylformamide
Dimethyl sulfoxide
Dimethyl Sulfoxide
Surface-Active Agents
Defects
Molecules
Desorption
defects
Surface active agents
desorption
surfactants
molecules
Scanning tunneling microscopy
stirring
Adsorbates
Gold
Vacancies

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

Cite this

Molecular-level approach to inhibit degradations of alkanethiol self-assembled monolayers in aqueous media. / Yang, Guohua; Amro, Nabil A.; Starkewolfe, Zane B.; Liu, Gang-yu.

In: Langmuir, Vol. 20, No. 10, 11.05.2004, p. 3995-4003.

Research output: Contribution to journalArticle

Yang, Guohua ; Amro, Nabil A. ; Starkewolfe, Zane B. ; Liu, Gang-yu. / Molecular-level approach to inhibit degradations of alkanethiol self-assembled monolayers in aqueous media. In: Langmuir. 2004 ; Vol. 20, No. 10. pp. 3995-4003.
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