Mater. Res. Soc. Symp. Proc. Vol. 1793 © 2015 Materials Research Society DOI: 10.1557/opl.2015. Single Molecular Layer Adaption of Interfacial Surfaces by Cyclic Azasilane "Click- Chemistry” Annalese F. Maddox 1 , Janis G. Matisons, 1 Mani Singh 1 , Joel Zazyczny 1 , Barry Arkles 1 1 Gelest, Inc., 11 East Steel Rd, Morrisville, PA 19067, U.S.A. ABSTRACT The surfaces of inorganic substrates containing hydroxyl groups can be adapted to a variety of physical and chemical requirements by reaction with cyclic azasilanes. The moderately-strained ring structure of cyclic azasilanes containing adjacent Si and N atoms, along with the high oxophilicity of silicon, enables the high reactivity towards available hydroxyl groups on all siliceous surfaces investigated, including amorphous silica and borosilicate glass. The reaction occurs quantitatively at room temperature, requires no catalyst and has no byproducts. This investigation looks specifically at the reaction kinetics by means of DRIFT spectroscopy and quantifies extent of reaction by TGA. The less sterically-hindered the Si–N bond, the faster the reaction occurs. In all cases, the reaction is essentially complete in less than one minute. This study provides the first confirmation that the rate and extent of reaction without catalysis or byproducts of cyclic azasilanes conforms to the Sharpless requirements for “click chemistry” and can be deemed “click chemistry for surfaces.” INTRODUCTION Organofunctional silanes are well established as materials used in surface modification to obtain the desired surface characteristics as well as a means to connect two typically incompatible phases, of which one is typically a solid surface [1]. These silanes are referred to as silane coupling agents and consist of two types of substituents bonded to the silicon atom. The first is the organofunctional group, R, that provides the desired surface characteristics and compatibility with an organic medium. The second is the hydrolyzable group, such as an alkoxy (–OMe, –OEt) or a chloro (Cl), which is removed thereby allowing the silicon atom to bind to the inorganic surface. Alkoxy functional coupling agents are more commonly used than the chlorosilanes due to the ease of handling. Alkoxysilanes bind to an inorganic surface through concurrent hydrolysis and condensation reactions, which are either catalyzed by amines or by acids conducted at a pH between 3.5 and 5. The reaction eliminates alcohol as a byproduct and is typically conducted in an aqueous alcohol solution. For clarity and comparison, a simplified version is depicted for the complex, concurrent reactions of an aminoalkoxysilane with water and a surface hydroxyl in figure 1(a) [1-2]. Using a conventional silane coupling agent, such as 3-aminopropyltrimethoxysilane, requires optimization of the reaction conditions to achieve a smooth monolayer generally using treatment times of an hour or longer [3]. Furthermore, an aqueous environment is not ideal for moisture sensitive systems such as micro-electronics. While the adaptation of surfaces for specific physical or chemical interactions by conventional organofunctional silanes the nano- scale appears desirable, the reaction conditions with solvent, water as a co-reactant, catalysis and byproducts precludes their use in many applications. The requirements for substrate modification for nanofeatures is more consistent with molecular layer deposition “MLD” or in 655