Trimethylsilyl treated silica

Trimethylsilyl treated silica (CAS 68909-20-6) is a surface-modified fumed or precipitated silica in which hydroxyl groups on the silica surface have been capped with trimethylsilyl groups. This treatment renders the particle hydrophobic.

This treatment fundamentally changes how the silica interacts with organic matrices, enabling effective use in non-aqueous and moisture-sensitive systems. Untreated silica would perform poorly in these specific environments.

In coatings and adhesives, it functions as a rheology modifier, controlling sag, thixotropy, and flow in solvent-borne and UV-cure formulations. It avoids the viscosity instability associated with hydrophilic grades.

Silicone sealants and elastomers rely on it to achieve reinforcement and anti-settling performance. It maintains excellent compatibility with silicone polymer networks while improving the overall structural integrity.

In rubber compounding, it improves dispersion and processing consistency, particularly in systems where moisture uptake would compromise cure behavior. This ensures a more predictable and stable manufacturing process.

Plastics and construction sealant manufacturers also use it as an anti-caking and flow aid in powder systems. It serves as an effective foam suppressant in various reactive resin applications across the industry.

The product is supplied as a low-bulk-density white powder and is available in technical grade. Product differentiation is typically based on BET surface area, carbon content, and the degree of hydrophobic treatment.

Both fumed silica and precipitated silica substrates are used as the base material for this product. Each substrate is suited to different viscosity and reinforcement requirements depending on the final application.