Spontaneous Aryldiazonium Film Formation on 440C Stainless Steel in Nonaqueous Environments

Journal Article · Fri Nov 07 04:00:00 UTC 2014 · Langmuir

DOI: https://doi.org/10.1021/la503630f · OSTI ID:1184478

Small, Leo J. ^[1]; Hibbs, Michael R. ^[1]; Wheeler, David R. ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

The ability of three aryldiazonium salts to spontaneously assemble onto the surface of type 440C stainless steel is investigated in acetonitrile and the model hydraulic fluids tributyl phosphate and hexamethyldisiloxane. Competition between native oxide growth and organic film growth at different diazonium salt concentrations is monitored by electrochemical impedance spectroscopy. At 1 mM diazonium salt, 70% of total assembly is complete within 10 minutes, though total surface coverage by organics is limited to ≈ 0.15 monolayers. X-ray photoelectron spectroscopy confirms preferential bonding of organic molecules to iron over chromium, and adsorption of BF^-₄ onto the surface. Secondary ion mass spectroscopy reveals the ability of these films to self-heal when mechanically removed or damaged. Aging the diazonium salts in these nonaqueous environments demonstrates that up to 90% of the original diazonium salt concentration remains after 21 days at room temperature, while increasing the temperature beyond 50 °C results complete decomposition within 24 hours, regardless of solvent-salt combination.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: The Boeing Company
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1184478
• Report Number(s): SAND--2014-18685J; 540290
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 47 Vol. 30; ISSN 0743-7463
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English