Formation of Nanometer Domains of One Chemical Functionality in a Continuous Matrix of a Second Chemical Functionality by Sequential Adsorption of Silane Self-Assembled Monolayers

In this paper, we describe a procedure to prepare mixed self-assembled monolayers containing nanometer to micrometer domains of a chemical functionality surrounded by another chemical functionality, using sequential adsorption. Partial monolayers of octadecyltrichlorosilane (OTS) consisting of condensed islands with controlled size are prepared by varying the deposition conditions. The area surrounding the OTS islands is backfilled with 11-bromo undecyltrichlorosilane (BrUTS) or decyltrichlorosilane (DTS) to obtain nanometer to micrometer scale domains of OTS in a monolayer of DTS or BrUTS. First, we describe in detail the methodology to form partial OTS monolayers composed of domains of a desired size. Then, we discuss the procedure and optimum conditions for successful backfilling. These monolayers were analyzed by atomic force microscopy (AFM) to obtain height and friction images in contact and tapping modes. In addition, we have studied (1) the friction properties of various phases in OTS monolayers, (2) the morphology of monolayers on silicon substrates with various degrees of hydration, and (3) in situ adsorption of OTS monolayers using AFM.