Self-Assembled Monolayers of Long-Chain Hydroxamic Acids on the Native Oxides of Metals

John P. Folkers, Christopher B. Gorman, Paul E. Laibinis, Stefan Buchholz, George M. Whitesides, Ralph G. Nuzzo

Research output: Contribution to journalArticlepeer-review

Abstract

Long-chain alkanehydroxamic acids adsorb on the native oxides of metals and formed oriented self-assembled monolayers (SAMs). This study examined SAMs of hydroxamic acids on the native oxides of copper, silver, titanium, aluminum, zirconium, and iron. These SAMs were characterized using wettability, X-ray photoelectron spectroscopy (XPS), and polarized infrared external reflectance spectroscopy (PIERS). Alkanehydroxamic acids give better monolayers than the corresponding alkanecarboxylic acids on certain basic metal oxides (especially copper(II) oxide). On the native oxide of copper (which has an isoelectric point greater than the pKa of the hydroxamic acid), the ligand is bound to the surface predominantly as the hydroxamate. The strength of the interaction between copper oxide and the hydroxamate allows incorporation of polar tail groups into the monolayer. On acidic or neutral metal oxides (e.g., TiO2), the predominant species bound to the surface is the hydroxamic acid. Alkanehydroxamic acids on titanium dioxide bind relatively weakly but, nonetheless, form SAMs that are moee stable than those from carboxylic acids (although not as stable as those from alkanephosphonic acids).

Original languageEnglish (US)
Pages (from-to)813-824
Number of pages12
JournalLangmuir
Volume11
Issue number3
DOIs
StatePublished - Mar 1 1995

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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