AHTP-1003

Technical Data Sheet: Antmee® Hydroxy Terminated Polydimethylsiloxane

Product Name: Antmee® Hydroxy Terminated Polydimethylsiloxane
Chemical Description: α,ω-Dihydroxy Polydimethylsiloxane / Silanol Terminated Polydimethylsiloxane
CAS Number: 70131-67-8 
Molecular Structure: HO-[Si(CH₃)₂O]n-H
Industry Synonyms: 107 Gum / Hydroxy Silicone Oil / OH Polymer

1. Product Overview

Antmee® Hydroxy Terminated Polydimethylsiloxane is a series of linear, reactive polydimethylsiloxane fluids and gums terminated with silanol (-OH) functional groups at both chain ends. These polymers combine the inherent flexibility, thermal stability, and hydrophobicity of the silicone backbone with the condensation reactivity of terminal hydroxyl groups 。This bifunctional reactivity makes Antmee® Hydroxy Terminated PDMS an essential base polymer for room-temperature vulcanizing (RTV) silicone rubbers, a key intermediate for synthesizing higher molecular weight silicone gums, and an effective structure control agent in silicone compounding 。

The series spans an exceptionally broad viscosity range, from low-viscosity reactive fluids (approx. 20-30 cSt) to ultra-high molecular weight gums (up to 500,000+ cSt), allowing formulators precise control over crosslink density, mechanical properties, and processing characteristics.

2. Typical Physical & Chemical Properties

The following specifications represent the general physical properties of the Antmee® Hydroxy Terminated Polydimethylsiloxane series. Actual values vary significantly depending on the molecular weight and corresponding viscosity grade.

• Appearance: Clear, colorless to pale yellow transparent liquid or semi-solid gum (Visual) 

• Active Content: ≥ 98-100%

• Density (at 25°C): Approx. 0.95 – 0.98 g/mL 

• Hydroxyl Content: Inversely proportional to molecular weight; lower viscosity grades contain higher -OH content and thus exhibit higher reactivity 

• Thermal Service Range: -60°C to +250°C (continuous use)

• Solubility: Soluble in aromatic and aliphatic solvents (toluene, xylene, chloroform, carbon tetrachloride); low molecular weight grades show slight water solubility; high molecular weight gums require solvent dilution for handling 

Disclaimer: Typical values are representative of average production lots and should not be interpreted as guaranteed batch-specific specifications. Minor variations are expected due to normal manufacturing tolerances.

3. Standard Specifications by Viscosity Grade

Please refer to the specific Antmee® product code for detailed Certificate of Analysis (CoA) data, including precise hydroxyl content and molecular weight distribution.

Antmee® HTV-20 to HTV-100 (Viscosity Range: Approx. 20 cSt to 100 cSt)
These are low molecular weight, low-viscosity reactive fluids characterized by relatively high hydroxyl content (hydroxyl value approx. 4-8%). They exhibit high reactivity in condensation reactions and serve as reactive diluents, chain extenders, and intermediates for synthesizing block copolymers and modified silicone fluids. These grades are also widely used as structure control agents in silicone rubber compounding to prevent “structuring” (crepe hardening) by reacting with the silanol groups on silica filler surfaces, thereby improving processing characteristics and extending shelf life 。

Antmee® HTV-750 to HTV-5000 (Viscosity Range: Approx. 750 cSt to 5,000 cSt)
This is the core workhorse range for condensation-cure RTV silicone rubber formulations. These medium-viscosity OH polymers serve as the primary base polymer for one-component and two-component sealants, encapsulants, and molding compounds. They provide an optimal balance of flowability before cure and mechanical strength after crosslinking. When formulated with crosslinkers (such as alkoxysilanes) and catalysts, they cure at room temperature to form elastic, weather-resistant silicone elastomers.

Antmee® HTV-20000 to HTV-80000 (Viscosity Range: Approx. 20,000 cSt to 80,000 cSt)
High molecular weight hydroxy-terminated polymers exhibiting a honey-like or semi-solid consistency. Often referred to as “107 silicone rubber base” in industry terminology, these grades are the foundation for high-elongation, high-tensile-strength silicone elastomers 。They provide superior mechanical properties and are used in premium sealants, gaskets, and molded silicone goods requiring excellent tear resistance and recovery.

Antmee® HTV-100000 to HTV-500000+ (Viscosity Range: 100,000 cSt and above)
Ultra-high molecular weight silicone gums with extremely low hydroxyl content (hydroxyl value approx. 0.1-0.2%). These materials are highly viscoelastic solids that exhibit cold flow. They are primarily used as the base gum for millable high-consistency rubber (HCR) compounds and as masterbatch carriers. When compounded with fillers and vulcanizing agents (typically peroxides), these gums yield silicone elastomers with maximum physical strength, heat resistance, and compression set resistance. Due to their extreme viscosity, these grades typically require solvent processing or high-torque mixing equipment 。

4. Primary Applications

• RTV Silicone Rubber Base Polymer: Antmee® Hydroxy Terminated PDMS (particularly the 750-5000 cSt range) is the fundamental raw material for condensation-cure RTV silicones used in construction sealants, automotive gasketing, electronic potting, and mold making 。

• Silicone Rubber Compounding (Structure Control Agent): Low viscosity OH polymers (20-100 cSt) are added to silicone rubber compounds to react with the silanol groups on reinforcing silica fillers. This prevents premature crosslinking (structuring) during storage and improves filler dispersion, resulting in better processing and extended shelf life 。

• Synthesis Intermediate: Used as a starting material for producing higher molecular weight silicone gums, amino-functional silicones, and various organic-silicone copolymers via condensation or hydrosilylation chemistry 。

• Textile, Paper, and Leather Treatment: Emulsified OH polymers serve as durable softening agents and water repellents for fabrics, paper, and leather. The terminal hydroxyl groups allow for self-crosslinking or reaction with fabric substrates, providing washfast softness and improved hand feel 。

• Defoaming Agents: Low molecular weight grades are used as key components in the formulation of silicone-based defoamers and antifoam agents for industrial processes.

5. Packaging and Storage Information

• Packaging Options: Low to medium viscosity grades are available in 20 kg pails, 50 kg HDPE drums, or 200 kg steel drums. High viscosity gums are typically packaged in 20 kg pails or specially lined 200 kg drums to facilitate removal. Custom packaging available upon request.

• Shelf Life: 12 months from the date of manufacture when stored in the original, unopened container under recommended conditions.

• Storage Conditions: Store in a cool, dry, and well-ventilated area away from direct sunlight and sources of ignition. Keep containers tightly sealed to prevent contamination and unintended reaction with atmospheric moisture. Recommended storage temperature range: 2°C to 35°C 。High-viscosity gums should be stored at stable temperatures to minimize cold flow.