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Silicones & Silicates

Polysiloxanes di-Me hydroxy-terminated

CAS: 70131-67-8

Overview

Polysiloxanes di-Me hydroxy-terminated (CAS 70131-67-8 ), commercially known as hydroxy-terminated polydimethylsiloxane or PDMS-OH, is a reactive silicone polymer used as a building block and functional additive across silicone-based manufacturing.

The terminal hydroxyl groups enable direct participation in crosslinking and condensation cure reactions, making it a primary raw material rather than a passive additive in industrial formulations.

In sealant and elastomer production, it serves as the base polymer for room-temperature vulcanizing (RTV) silicone systems, where the hydroxyl end groups react with crosslinkers to form durable, flexible networks.

Coatings and release liner formulations use it to control surface energy and improve substrate wetting without compromising film integrity. In rubber compounding and tire manufacturing, it functions as a processing aid.

It acts as a reactive modifier that adjusts flow behavior and final mechanical properties. Textile and paper treatment processes apply it to impart softness, water repellency, and controlled slip to finished surfaces.

Supplied as a clear to slightly hazy viscous liquid, it is available across a broad viscosity range, typically from low-viscosity fluids to high-viscosity gums, to suit different processing requirements.

Technical grade is the standard commercial offering, with viscosity specifications used as the primary quality parameter for grade differentiation. Packaging ranges from drums to IBC containers depending on volume.

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Physical Properties

Melting Point<-60°C
Boiling Point182 °C
Density0.98 g/mL at 25 °C
Flash Point155 °F
AppearanceColorless to light yellow Liquid
FormLiquid
Water SolubilitySoluble in carbon tetrachloride, benzene, chloroform, diethyl ether, toluene and other organic solvents. Insoluble in water and ethanol.
Refractive Indexn 20/D 1.406

Trade & Regulatory

Storage Class10 - Combustible liquids
WGK (Germany)1

Other Names

Polydimethylsiloxane hydroxy terminated | Hydroxy-terminated polydimethylsiloxane

Related Products

Chemical Properties

CAS Number
70131-67-8
EC Number
615-070-3
Mol. Weight
-

Industries

Documentation