Hexamethyldisiloxane (MM/HMDS)

Hexamethyldisiloxane (MM/HMDS) is a low-viscosity, highly volatile organosilicon compound widely used as an end-capping agent, hydrophobic coating precursor, and inert reaction solvent in the pharmaceutical, semiconductor, and silicone industries. Thanks to its excellent chemical stability, low surface tension, and high silicon content, HMDS is an essential building block for linear and cyclic polydimethylsiloxanes (PDMS).

Technical Specification

Packaging and Storage

• Net weight 150kg steel drum or 750kg IBC tank.
• Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage.

Key Features & Benefits

• Ultra-low water content (<50 ppm) and metal ions (<10 ppb) in electronic-grade versions.
• Excellent hydrophobizing agent for silica, glass, and metal oxide surfaces.
• Volatile and leaves no residue after evaporation.
• High thermal stability and inertness under most conditions.
• Fully miscible with common organic solvents and silicone oils.

Primary Applications of Hexamethyldisiloxane (MM/HMDS)

Semiconductor & Electronics:
Photoresist adhesion promoter (HMDS primer) in photolithography
Dielectric and hydrophobic surface treatment
Cleaning and drying agent in wafer processing

Pharmaceutical & Analytical Chemistry:
Silylating agent for derivatization in GC-MS and LC-MS
Protection of hydroxyl groups during organic synthesis
Extraction solvent for APIs and intermediates

Silicone Manufacturing:
End-blocker (“M” units) for linear polydimethylsiloxanes (PDMS)
Chain terminator in silicone oil and rubber production

Personal Care & Cosmetics:
Volatile carrier and emollient in antiperspirants, hair care, and skin-care formulations
Improves spreadability and provides dry, non-greasy feel

Laboratory & Research:
Inert, moisture-scavenging solvent
Reagent for trimethylsilylation reactions

Frequently Asked Questions (FAQs)

Is HMDS used as a primer in semiconductor lithography?
Yes. Vapor or spin-on HMDS is the industry-standard adhesion promoter for photoresists on silicon wafers. It converts surface silanol groups (Si-OH) to trimethylsilylated groups (Si-O-Si(CH₃)₃), making the surface hydrophobic and improving resist adhesion.

Can HMDS be used in cosmetic formulations?
Absolutely. It is widely used as a volatile silicone carrier (INCI name: Hexamethyldisiloxane) in antiperspirants, deodorants, hair sprays, and skin creams due to its fast evaporation and dry feel.

Does HMDS react with water?
HMDS is moisture-sensitive and slowly hydrolyzes in the presence of water to form trimethylsilanol and hexamethyldisiloxane oligomers, but it is significantly more stable than chlorosilanes.

Can Hexamethyldisiloxane be used as a direct replacement for TMCS/TMCS mixtures in silylation?
Yes. HMDS is safer and easier to handle than TMCS (trimethylchlorosilane) and is widely used with catalysts such as TMSI or in BSA/TMCS/HMDS (3:2:3) mixtures for derivatization.

Where can I buy high-quality Hexamethyldisiloxane (MM/HMDS)?

You can contact us via email [email protected] for offers and bulk orders.