Hydrolysis and grafting of dimethylalkoxysilanes onto stainless steel |
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| Authors: | Julien Huser Sophie Bistac Christelle Delaite Didier Dentel Mickaël Derivaz Mohamed Zanouni |
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| Affiliation: | 1. Laboratoire de Photochimie et d'Ingénierie Macromoléculaires, Equipe Chimie et Physico‐Chimie des Polymères—Université de Haute‐Alsace, 3 rue Alfred Werner, Mulhouse Cedex, France;2. Institut de Science des Matériaux de Mulhouse (IS2M), UMR 7361 CNRS‐UHA, Université de Haute Alsace, Mulhouse, France;3. Equipe de Recherche en Mécanique, Matériaux et Métallurgie, Université Abdelmalek Essaadi, FST, Tangier, Morocco |
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| Abstract: | The grafting of trialkoxysilane molecules should also give rise to the formation of a siloxane network at the substrate's surface when trialkoxysilanes are used. Other candidates that might be able to act as adhesion promoters at metallic surfaces are dimethylalkoxysilanes. The advantage of dimethylalkoxysilanes is that only one silanol group is produced during the hydrolysis step, leading to the formation of a grafted monolayer onto the steel. Moreover, the chemical grafting of stainless steel, which exhibits a low surface reactivity, is of great interest for industrial applications such as adhesive bonding or coatings. The objective of this work was to chemically graft dimethylalkoxysilanes onto AISI 316L stainless steel and to analyze the grafted layer by X‐ray photoelectron spectroscopy (XPS). Investigation of the hydrolysis of these molecules in aqueous solutions was also performed by proton nuclear magnetic resonance spectroscopy (1H NMR). The grafting of 3‐(ethoxydimethylsilyl)propylamine (APDES) and 3‐glycidoxypropyldimethylethoxysilane (GPDES) was achieved onto stainless steel after a controlled hydrolysis reaction. A pH inferior or equal to 5 was necessary to obtain a sufficient hydrolysis of silanes. XPS results have evidenced the grafting of the silanes onto stainless steel. The signal of the Si 2p peak clearly showed the formation of a covalent bond between APDES and the stainless steel surface through the O atoms giving rise to a uniform layer of adsorbed molecules. Moreover, this grafted layer is strongly stable as no removal of the alkoxysilane was observed after immersion in hot water which is very critical for these molecules. Copyright © 2015 John Wiley & Sons, Ltd. |
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| Keywords: | alkoxysilane stainless steel adhesion 1H NMR XPS |
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