Molecular layers of hydroxamic acids in copper corrosion inhibition

Nanolayers of alkyl hydroxamic acids deposited on copper surface as a Langmuir-Blodgett (LB) and as a self-assembled molecular (SAM) layer were studied in acidic solutions. In order to produce the most compact Langmuir layers and transfer it onto solid surface, the influence of different factors (pH and temperature) on the Langmuir monolayers of two long-chain hydroxamic acids (CH3(CH2)(n)CONHOH; n = 14 (C16HA), 16 (C18HA)) has been studied by surface pressure-area isotherms, and Brewster angle microscope (BAM). The LB film deposition and SAM formation on metal substrates were characterized by contact angle measurement, as well as by sum frequency vibrational spectroscopy. The morphology of LB and SAM coated copper surface was visualized by atomic force microscopy. The inhibition activity of mono- and multi-molecular LB as well as SAM layers was monitored by electrochemical techniques as well. Experiments of nanocoated copper in aqueous acidic environment showed that both types of nanolayers enhance the durability of copper significantly and the increase in monolayer numbers increases the anticorrosion effect. (C) 2005 Elsevier B.V. All rights reserved.