A CHEMICAL MODIFICATION OF ALKANETHIOL SELF-ASSEMBLED MONOLAYERS WITH ALKYLTRICHLOROSILANES FOR THE PROTECTION OF COPPER AGAINST CORROSION

A self-assembled monolayer of 11-mercapto-1-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 alkylsiloxane 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 FTIRAS. The protection abilities of alkylsiloxane modified 11-mercapto-1-undecanol layers against copper corrosion obtained in aerated 0.5M Na2SO4 by impedance and polarization measurements were higher 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 11-mercapto-1-undecanol monolayer 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.