Surface Technology

Organofunctional silanes can be optimally applied to inorganic surfaces such as glass, metal, metal oxides, pigments, etc. and thereby allow for the modification and functionalisation of these surfaces. There are many procedures for chemically binding silanes to a surface such as the gas phase technologies CVD, ALD or from the liquid phase as in the SOL GEL process for which metal acid ester is also used. For smooth surfaces, silanes are often applied from alcoholic-aqueous solutions by dipping or brushing or also by spraying for rough surfaces such as powders or inorganic pigments.

Organofunctional silanes are often bifunctional.  Alkoxy or other leaving groups bound to silicon such as amino, amido or chloro groups hydrolyse in the presence of moisture, creating the reactive intermediate phase – “silanol”. Silanol then chemically binds to inorganic surfaces, ideally as a monomolecular layer. The surface can be arbitrarily changed with the free selection of the ligand for the silicon, the “organofunctional group”. The selection provides adhesion to organic substrates or a change of polarity at the surface. Typical representatives for adhesion are amino, epoxy, methacryl or vinylsilanes as these combine with the polymer side as for example in glass-fibre reinforced plastics. Non-functional alkylsilanes are also used for hydrophobisation. Concrete hydrophobisation is a classic example of this. Fluorosilanes have a highly water and dirt-repellent effect, which can be seen in extremely high contact angles.

For gas phase processes such as CVD or ALD, silanes are most often degraded and then separate on surfaces, which can then also be of an organic nature, as SiOx or SiNx.

Various product classes from abcr are used in the sol gel procedure. In addition to the main component tetraethoxysilane TEOS, other components such as organofunctional silanes, metal acid ester or di(meth)acrylate are also available.

abcr offers more than just the common silanes. Our production facility in Spain focusses on specialties. A few thousand silane types for special applications are already available, and we are happy to synthesise any desired molecule if it is not available, from the laboratory standard to commercial quantities.

Silane applications on surfaces are extraordinarily varied. Many industry branches take advantage of the adhesive property. This especially applies to paints, lacquers, adhesives and sealants, rubber, glass and plastics. Coating with the sol gel procedure provides excellent scratch resistance. The property of hydrophobisation can, e.g., be used for building protection, anti-corrosion coating or the coating of powders. Fluorosilanes that create an extremely hydrophobic and oleophobic surface can also be used for popular applications such as anti-graffiti or dirt-repellent glass surfaces (bathroom, car window).