A Chemical Modification of Alkanethiol Self‐Assembled Monolayers with Alkyltrichlorosilanes for the Protection of Copper Against Corrosion

Abstract

A self-assembled monolayer of 11-mercapto-l-undecanol chemisorbed on the copper surface was chemically modified by reactions of the monolayer with alkyltrichlorosilane and water to form alkylsiloxane polymer in the film. The alkylsilox-ane modified monolayers were characterized by x-ray photoelectron (XPS) and Fourier transform infrared reflection spectroscopies (FTIRAS) and impedance, polarization, and contact angle measurements. A structure of the cross-linked alkylsiloxane modified layer adsorbed on the copper surface was confirmed by XPS and FT!RAS. The protection abilities of alkylsiloxane modified 11-mercapto-l-undecanol layers against copper corrosion btained in aerated 0.hM Na=SO ~ by impedance and polarization measurements werehigher than those of alkanethiol monolayers. The highest values of the protection abilities were obtained in the region of the carbon number n between 4 and 8 in alkyltrichlorosilanes (n = 1 18). The lower protection ability at n = 18 may be attributed to disordered arrangements of the self-assembled layer on the surface. The contact angle of the copper surface covered with the l l-mercapto- l-undecanol m nolayer increased by chemical modification with alkyltrichlorosilane and water but a clear relation between the contact angle and n could not be obtained in this study. A densely packed self-assembled monolayer of alkane-thiol CnH2~+ISH with a higher carbon umber has been pre-