A Mechanistic Explanation of the Peculiar Amphiphobic Properties of Hybrid Organic鈥揑norganic Coatings by Combining XPS Characterization and DFT Modeling

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• 作者：Alessandro Motta ; Oliviero Cannelli ; Alice Boccia ; Robertino Zanoni ; Mariarosa Raimondo ; Aurora Caldarelli ; Federico Veronesi
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：September 16, 2015
• 年：2015
• 卷：7
• 期：36
• 页码：19941-19947
• 全文大小：447K
• ISSN：1944-8252

文摘

We report a combined X-ray photoelectron spectroscopy and theoretical modeling analysis of hybrid functional coatings constituted by fluorinated alkylsilane monolayers covalently grafted on a nanostructured ceramic oxide (Al₂O₃) thin film deposited on aluminum alloy substrates. Such engineered surfaces, bearing hybrid coatings obtained via a classic sol鈥揼el route, have been previously shown to possess amphiphobic behavior (superhydrophobicity plus oleophobicity) and excellent durability, even under simulated severe working environments. Starting from XPS, SEM, and contact angle results and analysis, and combining it with DFT results, the present investigation offers a first mechanistic explanation at a molecular level of the peculiar properties of the hybrid organic鈥搃norganic coating in terms of composition and surface structural arrangements. Theoretical modeling shows that the active fluorinated moiety is strongly anchored on the alumina sites with single Si-O-Al bridges and that the residual valence of Si is saturated by Si鈥揙鈥揝i bonds which form a reticulation with two vicinal fluoroalkylsilanes. The resulting hybrid coating consists of stable rows of fluorinated alkyl chains in reciprocal contact, which form well-ordered and packed monolayers.