Anchoring of sulfur‐containing alkylphosphonic and semifluorinated alkylphosphonic molecules on a polycrystalline aluminum substrate

Abstract

Abstract Self‐assembly on a polycrystalline aluminum substrate of two sulfur‐containing alkylphosphonic acids, CH 3 (CH 2 ) 11 S (CH 2 ) 2 PO(OH) 2 , and CF 3 (CF 2 ) 7 (CH 2 ) 2 S(CH 2 ) 2 PO(OH) 2 , has been compared with CH 3 (CH 2 ) 15 PO(OH) 2 . The reaction of the phosphonic head groups with the hydroxyls at the alumina surface to form phosphonates was studied with X‐ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection‐absorption spectroscopy (PM‐IRRAS). Barrier effects of the resulting layers was assessed by electrochemical polarization curves. With the conditions used in the present work for the self‐assembly reaction, it appears that the sulfur‐containing molecules do not perform as well as CH 3 (CH 2 ) 15 PO(OH) 2 in terms of film quality. Questions are raised about the possibility that the sulfur‐containing molecules could undergo cleavage during surface modification. Copyright © 2008 John Wiley & Sons, Ltd.