Silanization

Silanization is the covering of a surface with organofunctional alkoxysilane molecules. Mineral components like glass and metal oxide surfaces can all be silanized, because they contain hydroxyl groups which attack and displace the alkoxy groups on the silane thus forming a covalent -Si-O-Si- bond. The goal of silanization is to form bonds across the interface between mineral components and organic components present in paints, adhesives, etc. Silanization (or siliconization) of glassware increases its hydrophobicity and is used in cell culturing to reduce adherence of cells to flask walls.^[1]

Properties

Organofunctional alkoxysilane molecules have both organic and inorganic properties.

Organofunctional alkoxysilanes

The alkoxy groups usually used are the methoxy (-OCH₃) and the ethoxy (-OCH₂CH₃) groups. The organofunctional alkoxysilanes are classified according to their organic functions:

Aminosilanes

The organic function is a primary or secondary amine:

• APTES (3-aminopropyl)-triethoxysilane CAS# 919-30-2

Structural formula of (3-aminopropyl)triethoxysilane (APTES)

• APDEMS (3-aminopropyl)-diethoxy-methylsilane
• APDMES (3-aminopropyl)-dimethyl-ethoxysilane
• APTMS (3-aminopropyl)-trimethoxysilane CAS# 13822-56-5

Glycidoxysilanes

The organic function is an epoxide:

• GPMES (3-glycidoxypropyl)-dimethyl-ethoxysilane

Mercaptosilanes

The organic function is a thiol:

• MPTMS (3-mercaptopropyl)-trimethoxysilane
• MPDMS (3-mercaptopropyl)-methyl-dimethoxysilane

References