Nie Heng-Yong, Walzak Mary J, McIntyre N Stewart
Surface Science Western, Room G-1, WSC, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
J Phys Chem B. 2006 Oct 26;110(42):21101-8. doi: 10.1021/jp062811g.
We describe a simple experimental approach for delivering self-assembled monolayers (SAMs) of octadecylphosphonic acid (OPA) on many oxide surfaces using a nonpolar medium with a dielectric constant around 4 (e.g., trichloroethylene). This approach readily results in the formation of full-coverage OPA SAMs on a wide variety of oxide surfaces including cleaved mica, Si wafer, quartz, and aluminum. Especially, the availability of delivering full-coverage OPA SAM on a Si wafer is unique, as no OPA SAMs at all could be formed on a Si wafer when using a polar OPA solution. The reason a nonpolar solvent is superior lies in the very fact that the hydrophilic OPA headgroup tends to escape from the nonpolar solution and is thus enriched at the medium-air interface. It is these OPA headgroups seeking a hydrophilic surface that make possible the well-controlled OPA monolayer on an oxide surface.
我们描述了一种简单的实验方法，可使用介电常数约为4的非极性介质（如三氯乙烯），在许多氧化物表面上沉积十八烷基膦酸（OPA）的自组装单分子层（SAMs）。这种方法能够轻松地在多种氧化物表面上形成全覆盖的OPA SAMs，包括解理云母、硅片、石英和铝。特别值得一提的是，在硅片上实现全覆盖OPA SAMs的方法具有独特性，因为使用极性OPA溶液时，根本无法在硅片上形成OPA SAMs。非极性溶剂更具优势的原因在于，亲水性的OPA头基倾向于从非极性溶液中逸出，从而在介质-空气界面富集。正是这些寻求亲水性表面的OPA头基，使得在氧化物表面能够形成可控性良好的OPA单分子层。
