In the production of silicone rubber, coatings, and composite materials, while fumed silica serves to enhance reinforcement properties, the abundance of hydroxyl groups on its surface renders it prone to moisture absorption and agglomeration, leading to difficulties in dispersion and increased processing viscosity. Hexamethyldisilazane (HMDS; IOTA 011) serves as a crucial surface treatment agent specifically designed to address this challenge.

HMDS reacts with the hydroxyl groups present on the surface of fumed silica, forming a hydrophobic organosilicon layer on the powder particles. This process significantly reduces the powder's moisture absorption while simultaneously improving its flowability and dispersion characteristics. Fumed silica treated with HMDS not only integrates more uniformly with systems such as silicone rubber and resins but also effectively lowers system viscosity and enhances processing stability.

In both liquid silicone rubber (LSR) and high-temperature vulcanized (HTV) silicone rubber applications, HMDS-treated fumed silica improves the processing performance of the rubber compound while enhancing the transparency, resilience, and mechanical properties of the final product. Furthermore, it helps minimize performance fluctuations caused by moisture absorption during storage.

Beyond fumed silica, HMDS is also widely utilized for the hydrophobic modification of various other inorganic powders—such as diatomaceous earth and titanium dioxide—finding significant application value in the fields of electronic materials, coatings, sealants, and composite materials.

Distinguished by its high reactivity and exceptional hydrophobic treatment capabilities, HMDS has established itself as a key organosilicon additive widely employed in the field of powder surface modification.