Silanes & Siloxanes

abcr is also a specialist for the siloxane product class. abcr’s product range includes more than commercially available products such as polydimethylsiloxanes (PDMS) as oils with various viscosities. We also synthetize highly pure products for medical applications or specifically functionalised siloxanes.

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). Silanes are also in demand in the pharmaceutical industry as synthesis building blocks, reductants or protection groups. 

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). Silanes are also in demand in the pharmaceutical industry as synthesis building blocks, reductants or protection groups. 

Standard siloxanes are also used in cleaning agents, cosmetics, deodorants, detergents or as defoamers. Highly pure products stand out from the standard assortment because the qualities must satisfy high requirements such as for medical and pharmaceutical applications. Functionalised siloxanes are often optimised for the application, which means that organic groups are bound to the molecule chains that subsequently create special surface characteristics. Methacryl units additionally provide linking. Water and oxygen-permeable contact lenses are the best-known example. 

We are happy to synthesise any desired molecule if it is not available – from the laboratory standard to commercial quantities. 

The designation silane, which actually stands for silicon-hydrogen compounds, is often used for organofunctional silanes of the structure R_xSi−(OR`)_(4-x).  

Siloxanes have the general structure R₃Si−[O−SiR₂]_n−O−SiR₃ (R = hydrogen, alkyl or an arbitrarily selectable organic rest). The designation silicones is also used if no hydrogen atoms are present and the chains are longer.  

Organofunctional silanes can be optimally applied to inorganic surfaces such as glass, metal, metal oxides, minerals, pigments, etc. and thereby allow for 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. Metal acid esters from abcr are 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 substituents 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 modification 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 pure 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 SiO_x or SiN_x. The silanes are so-called precursors in these procedures like the metal complexes from the abcr programme. 

Various abcr product classes 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 focuses on specialities. A few thousand silane types are available for special requirements.