Surface Modification of Glass Beads with an Aminosilane Monolayer

Self-assembled monolayers (SAMs) are monomolecular layers which are spontaneously formed upon immersing a solid substrate into a solution containing functional molecules. The most attractive feature of SAMs is molecular level control over the modification of surfaces, and incorporation of multiple or multilayer molecular components onto the monolayer leads to various functional properties. SAMs can be prepared using different types of molecules and different substrates. Commonly employed examples are alkylsiloxane monolayers, fatty acids on oxide materials and alkanethiolate monolayers1−3. SAM formation provides surface functionalisation by organic molecules containing suitable functional groups like –SH, –CN –COOH, –NH2 and silanes. These surfaces can be effectively used to build up interesting nano-level architectures. The first types of strongly bound chemisorbed monolayers using silane compounds were reported by Sagiv, where glass or oxidised silicon surfaces were etched to clean and coat them with active silanol (Si-OH) groups . Recently, increasing effort has been directed towards potential applications of silane SAMs, particularly chloro and terminal amine groups which have the capability of attaching larger molecules6−9. Flexibility with respect to terminal functionalities of the organic molecules allows control of the hydrophobicity or hydrophilicity of surfaces. ∗Corresponding author