Understanding the intrinsic chemical properties of raw materials is fundamental for any B2B procurement or R&D professional. Silanol-terminated polydimethylsiloxane (PDMS), identified by its CAS number 70131-67-8, is a silicon-based polymer whose unique terminal hydroxyl (-OH) groups imbue it with specific reactivities and beneficial characteristics. As a dedicated supplier of fine chemicals, NINGBO INNO PHARMCHEM CO.,LTD. provides insight into why this material is a critical component in numerous industrial applications.

The chemical formula for silanol-terminated PDMS is typically represented as HO-[(CH3)2SiO]nH. This linear chain structure, capped with silanol groups, is the key to its functionality. The silanol groups are moderately acidic and readily undergo condensation reactions, especially in the presence of catalysts or when exposed to moisture. This property is precisely what makes it an excellent base polymer for condensation-cure silicone systems, most notably RTV (Room Temperature Vulcanizing) sealants. When formulated with crosslinkers and moisture, the silanol ends react, forming stable siloxane (Si-O-Si) crosslinks that result in a cured elastomeric network.

Key physical properties often specified for silanol-terminated PDMS include its viscosity and hydroxyl content. For instance, a product might be specified with a viscosity of 20-30 mm²/s at 25°C and a minimum hydroxyl content of 9.0%. These parameters are critical for formulators who need to predict reaction rates, processing behavior, and the final physical properties of their products, such as flexibility, adhesion, and thermal resistance.

The applications stemming from these properties are diverse. In the sealant industry, the controlled condensation of silanol-terminated PDMS allows for the creation of user-friendly one-component (RTV-1) sealants that cure upon exposure to ambient humidity. For textile and leather treatments, these fluids can provide water-repellent and softening effects due to the inherently hydrophobic nature of the polydimethylsiloxane backbone and the surface-active nature of the polar silanol ends. In cosmetics and personal care, the fluid's smooth, slippery feel and conditioning properties make it a valuable ingredient. For R&D scientists and procurement managers, buying this chemical directly from a reputable manufacturer ensures access to consistent specifications and reliable performance data.

The thermal stability and chemical inertness of the PDMS backbone, combined with the reactivity of the silanol termini, make silanol-terminated PDMS a highly versatile intermediate. As a trusted supplier, NINGBO INNO PHARMCHEM CO.,LTD. emphasizes the importance of understanding these chemical benefits to make informed purchasing decisions. Sourcing this material can lead to significant improvements in product performance and manufacturing efficiency, underscoring its value in today's competitive markets.