Dynasylan® M

Dynasylan® M is a colorless or slightly yellow, low-viscosity liquid with an SiO₂ content of 39.5%. Use does not require acid- or alkali-catalyzed hydrolysis. Dynasylan® M easily hydrolyses upon addition of water.
Since all four methoxy groups are able to participate in this reaction, Dynasylan® M is regarded as tetrafunctional. Hydrolysis leads to silanol groups which, in a subsequent condensation reaction, form very stable siloxane bonds (-Si-O-Si-). Condensation starts before hydrolysis is complete. During storage of these hydrolysates condensation, continues until a gel is formed, where the rate depends on the degree of hydrolysis.
Dynasylan® M is a ready source of silic acid for many applications. Silic acid is usually obtained by hydrolysis or thermally by condensation at elevated temperature. The resulting silicic acid bonds well to many inorganic substrates and can be deposited in situ in a controlled manner. The surfaces of glass, metals, pigments, fillers and synthetic fibers can be coated with a very thin SiO₂ layer in order to improve chemical and thermal stability and mechanical properties.
Dynasylan® M is an important starting material for sol-gel processes, where the additional use of alkylalkoxysilanes (e. g. Dynasylan® MTMS) can give the siloxane network a somewhat organic character as a result of the incorporation of alkyl groups.
It is also possible to construct an inorganic/organic network by adding silanes containing organofunctional groups (e.g. aminopropyl groups) and polymerizing with organic precursors. This principle makes it possible to obtain highly scratch- and abrasion-resistant coatings.
Partial hydrolysis gives hydrolysates of Dynasylan® M whose shelf life depends on the amount of water and solvent used. The amount of water determines the activity of the hydrolysate. Activity and shelf life are inversely proportional. The correct choice of the amount of water can give hydrolysates which have a shelf life of a few months.