Hexamethyldisiloxane (MM/HMDSO) CAS 107-46-0

What Is Hexamethyldisiloxane?

Hexamethyldisiloxane is a volatile, low-viscosity organosilicon liquid identified by CAS No. 107-46-0. It consists of two trimethylsilyl groups connected by an oxygen atom and is commonly abbreviated as MM or HMDSO.

Its combination of low viscosity, volatility, hydrophobicity and trimethylsiloxy functionality makes it useful as a silicone raw material, PDMS end-blocker, specialty process fluid and precursor for plasma-deposited organosilicon or silicon oxide-like coatings.

AOZUN supplies hexamethyldisiloxane for industrial applications, silicone manufacturing, surface treatment and qualified electronic-material processes. Available specifications should be confirmed against the current technical data sheet and batch certificate of analysis.

Is Hexamethyldisiloxane Organic or Inorganic?

Hexamethyldisiloxane is classified as an organosilicon compound.

Although its molecular structure contains silicon and a siloxane bond, it also contains six methyl groups bonded to silicon. It is therefore commercially classified with organic and organosilicon specialty chemicals rather than inorganic silicon compounds.

Recommended product categories include:

• Organosilicon chemicals

• Specialty chemicals

• Fine chemicals

• Silicone raw materials

• Organosilicon intermediates

• Electronic-material precursors

Is Hexamethyldisiloxane a Fine Chemical or an Intermediate?

Hexamethyldisiloxane can be classified as both a specialty fine chemical and an organosilicon intermediate, depending on its application.

In silicone manufacturing, it functions as a raw material or end-blocking intermediate. In plasma coating and semiconductor-related processes, high-purity HMDSO functions as a specialty precursor. When used as a volatile process fluid, it is normally treated as a specialty organosilicon chemical.

For website navigation, the most accurate primary category is:

Fine Chemicals → Organosilicon Intermediates

Why MM or HMDSO Is the Correct Abbreviation

Hexamethyldisiloxane is correctly abbreviated as MM or HMDSO. The abbreviation “HMDS” is frequently used for a different chemical: hexamethyldisilazane.

Buyers should always confirm the CAS number and molecular formula when requesting a quotation. Using “HMDS” alone may result in an inquiry for the wrong chemical.

Product Identification at a Glance

The values above are typical reference data and should not be treated as batch specifications. Buyers should use the current COA, TDS and SDS for acceptance and handling decisions.

Typical Hexamethyldisiloxane Specifications

The following table presents a typical industrial-grade specification framework.

Electronic and semiconductor applications may require substantially tighter limits for water, metals, chloride, particles and nonvolatile residue. These limits must be defined in the purchase specification instead of being assumed from the general assay.

An assay of 99% does not automatically mean the product is suitable for electronic processing. Trace contamination profiles can be more important than total assay for deposition and wafer-related applications.

How Does Hexamethyldisiloxane Work in Silicone and Plasma Processes?

HMDSO contains two trimethylsilyl groups connected through a siloxane oxygen. This compact structure gives the material its low viscosity and volatility while allowing it to act as a source of trimethylsiloxy functionality or as an organosilicon vapor precursor.

Its role depends on the process. In silicone polymer production, it can participate in equilibration and control terminal groups. In plasma or vapor-deposition systems, its vapor is activated and converted into thin organosilicon or silicon oxide-like films.

As a PDMS End-Blocker

Hexamethyldisiloxane can provide trimethylsiloxy end groups during the manufacture of polydimethylsiloxane fluids.

Under an appropriate silicone equilibration process, these terminal groups help limit chain growth and influence the molecular weight and viscosity of the resulting polymer. The required HMDSO ratio depends on the polymer system, catalyst, starting siloxanes and target viscosity.

The product should therefore be described as a PDMS end-blocker or methyl-terminating raw material, rather than as a universal silicone catalyst.

As a Plasma and CVD Precursor

HMDSO vapor can be introduced into plasma-enhanced chemical vapor deposition and related coating systems. Plasma activation fragments the molecule and allows organosilicon films to form on suitable substrates.

Film properties depend on the equipment, oxygen ratio, energy input, pressure, substrate and other process conditions. Depending on the system, the deposited layer may be relatively organic and hydrophobic or more silica-like.

Potential uses include:

• Hydrophobic thin films

• Protective organosilicon coatings

• Silicon oxide-like barrier layers

• Surface-energy modification

• Plasma-polymerized functional coatings

• Semiconductor and electronic-material deposition processes

HMDSO should not be confused with HMDS photoresist primer. HMDSO is commonly used as a deposition precursor, while HMDS is the material more commonly associated with photoresist adhesion promotion.

As a Volatile Process Fluid

Its low viscosity, low surface tension and volatility can make HMDSO useful in selected specialty processes where rapid spreading and subsequent evaporation are required.

Compatibility, residue level, emissions controls and applicable regulations must be evaluated before use. It should not automatically be treated as a direct replacement for conventional solvents, cyclic siloxanes or low-viscosity PDMS fluids.

Main Applications of Hexamethyldisiloxane

Silicone Fluid and Polymer Manufacturing

HMDSO is used as an end-blocking or chain-terminating raw material in selected silicone polymer processes. It can help control the terminal structure and molecular-weight distribution of PDMS-type fluids.

Typical purchasing priorities include:

• Assay

• Water content

• Color

• Refractive index

• Nonvolatile residue

• Consistency between batches

Plasma-Deposited Hydrophobic Coatings

HMDSO can serve as an organosilicon precursor for plasma-polymerized coatings. These coatings may be applied to glass, metals, polymers and other compatible substrates.

Possible objectives include reducing surface energy, improving water repellency or creating a thin functional barrier. The final performance depends on the deposition process and substrate preparation.

Electronic and Semiconductor Materials

High-purity HMDSO grades may be used in chemical vapor deposition, plasma deposition and spin-on dielectric-related processes.

Electronic applications may require controls for:

• Trace metals

• Chloride and ionic contamination

• Water content

• Particles

• Nonvolatile residue

• Packaging cleanliness

• Batch-to-batch consistency

A general industrial grade should not be presented as electronic grade unless the impurity profile and packaging system have been specifically qualified.

Surface Treatment and Specialty Coatings

HMDSO may be used in research and industrial processes for organosilicon surface modification. Applications should be validated for the substrate, coating equipment and required durability.

Its hydrophobic character does not mean that simply wiping liquid HMDSO onto a surface will produce a permanent coating. Durable films normally require a controlled deposition, reaction or formulation process.

Specialty Solvent and Process Applications

HMDSO may function as a low-viscosity specialty process fluid in compatible systems. Before use, buyers should evaluate:

• Solvency

• Elastomer and seal compatibility

• Flash-point requirements

• Recovery or ventilation systems

• Residue limits

• Environmental restrictions

• Local VOC rules

Laboratory and Materials Research

Research laboratories use HMDSO in organosilicon chemistry, plasma science, thin-film studies and materials-surface research.

It should not be described as equivalent to the HMDS reagent commonly used for silylation or GC sample derivatization. Those methods generally refer to hexamethyldisilazane, not hexamethyldisiloxane.

HMDSO vs HMDS: Which Product Do You Need?

Choose HMDSO when the requirement involves:

• CAS No. 107-46-0

• Si–O–Si structure

• Silicone end-blocking

• PDMS molecular-weight control

• Plasma-polymerized organosilicon films

• CVD or thin-film deposition precursor

• Volatile siloxane process fluid

Choose HMDS when the requirement involves:

• CAS No. 999-97-3

• Si–NH–Si structure

• Photoresist adhesion promotion

• Surface silanization

• Chemical silylation

• Laboratory derivatization

• Conversion of active-hydrogen groups to trimethylsilyl derivatives

The two products have different structures, reactivity, safety documentation and commercial applications. They should not be substituted without technical validation.

HMDSO vs Cyclic Siloxanes and Low-Viscosity PDMS

These materials may have similar handling characteristics in some formulations, but they are not chemically equivalent.

How to Select the Right HMDSO Grade

1. Confirm the Chemical Identity

The purchase order should state:

• Hexamethyldisiloxane

• MM or HMDSO

• CAS No. 107-46-0

• Required grade

• Required test methods

This prevents confusion with hexamethyldisilazane.

2. Match the Assay to the Application

General silicone manufacturing may accept a standard industrial grade, while electronic and deposition applications can require a higher-purity product with detailed trace-impurity limits.

Do not select a grade using assay alone.

3. Define Critical Impurities

Depending on the process, critical values may include:

• Water

• Chloride

• Metals

• Color

• Nonvolatile residue

• High-boiling impurities

• Related siloxanes

• Particles

Ask the supplier which items are routinely tested and which require a custom analytical agreement.

4. Review Packaging Compatibility

Because HMDSO is volatile and highly flammable, packaging must be properly closed, compatible with the product and approved for the relevant transport mode.

High-purity applications may also require cleaned packaging, controlled filling and documented container materials.

5. Request a Representative COA

Reviewing a representative certificate of analysis before ordering helps establish whether the supplier’s routine controls match the buyer’s acceptance criteria.

Final acceptance should be based on the COA for the delivered batch.

Packaging and Supply

Packaging options depend on order quantity, destination, grade and dangerous-goods transport requirements.

Available supply formats may include:

• Approved metal drums

• Suitable intermediate bulk packaging where permitted

• Laboratory or sample-size containers

• Customer-agreed packaging for qualified high-purity grades

Exact net weight, container material, pallet configuration and transport method should be confirmed in the quotation.

Do not transfer HMDSO into an unapproved plastic or general-purpose container without first checking chemical compatibility, vapor control and dangerous-goods requirements.

Storage and Handling

Store hexamethyldisiloxane in a cool, dry and well-ventilated flammable-liquids area.

Recommended precautions include:

• Keep containers tightly closed.

• Keep away from heat, sparks, flames and hot surfaces.

• Prohibit smoking in handling and storage areas.

• Ground and bond containers and receiving equipment.

• Use suitable explosion-protected ventilation and electrical equipment.

• Prevent static-electric discharge.

• Use non-sparking tools where required.

• Avoid contact with strong oxidizing agents.

• Prevent release into drains, soil and surface water.

• Follow the current supplier SDS and local regulations.

For high-purity applications, moisture control may be important for product quality even though HMDSO is not normally treated as a readily hydrolyzing chlorosilane.

Safety and Environmental Information

Hexamethyldisiloxane is a highly flammable liquid and vapor. Its vapor may form an ignitable mixture with air and may travel to an ignition source.

Supplier safety data also classifies the substance as hazardous to aquatic life with potentially long-lasting effects. Spills should be contained using appropriate non-sparking equipment and compatible absorbent material.

Workers should use ventilation and personal protective equipment selected through the site’s risk assessment. Safety glasses or goggles, suitable gloves and protective clothing may be required.

The information on this page is a commercial product overview and does not replace the current SDS.

Transport Information

Typical dangerous-goods transport information includes:

Transport classification must be confirmed using the current SDS, concentration, packaging, destination and applicable ADR, IMDG, IATA or local regulations.

What Documents Should an HMDSO Supplier Provide?

A qualified supplier should be able to provide the documents appropriate to the grade and destination, including:

• Certificate of Analysis

• Safety Data Sheet

• Technical Data Sheet

• Product specification

• Batch and traceability information

• Packaging details

• Dangerous-goods transport information

• Regulatory or inventory statements where available

• Additional impurity data for qualified high-purity grades

Buyers should not rely on a general website table when the process requires a tightly controlled impurity profile.

Why Source Hexamethyldisiloxane from AOZUN?

AOZUN supports international buyers seeking industrial and specialty organosilicon chemicals.

Our supply service can include:

• Specification confirmation before quotation

• Batch COA availability

• Industrial and application-specific grade discussions

• Sample evaluation support

• Dangerous-goods packaging coordination

• Export documentation

• Flexible commercial quantities

• Technical communication for silicone and coating applications

Final product suitability remains subject to the buyer’s formulation, process trials, regulatory review and quality approval.

Information to Include in Your RFQ

To receive a more accurate quotation, provide:

1. Product name and CAS number

2. Required assay or grade

3. Critical impurity limits

4. Intended application

5. Required quantity

6. Packaging preference

7. Destination country and port

8. Required delivery schedule

9. Documentation requirements

10. Whether a sample or representative COA is needed

For electronic applications, also specify required limits for water, metals, chloride, particles and nonvolatile residue.

Frequently Asked Questions

What is the correct abbreviation for hexamethyldisiloxane?

MM and HMDSO are the preferred abbreviations. “HMDS” is commonly used for hexamethyldisilazane, CAS No. 999-97-3.

What is the CAS number of hexamethyldisiloxane?

The CAS number is 107-46-0.

Is HMDSO an organic or inorganic chemical?

It is an organosilicon compound and is generally classified commercially as an organic specialty chemical.

Is HMDSO a fine chemical or an intermediate?

It can be both. It is a specialty fine chemical when supplied for controlled technical applications and an organosilicon intermediate when used to manufacture silicone products.

Is HMDSO the same as HMDS?

No. HMDSO is hexamethyldisiloxane and contains a Si–O–Si linkage. HMDS is hexamethyldisilazane and contains a Si–NH–Si linkage.

Is HMDSO a photoresist adhesion promoter?

HMDSO is mainly used as an organosilicon deposition precursor in electronic and plasma processes. The material commonly used as a photoresist adhesion promoter is HMDS, or hexamethyldisilazane.

Can HMDSO be used as a silylating reagent?

HMDSO should not be presented as a direct substitute for HMDS, TMCS or other reactive silylation reagents. Its reactivity and applications are different.

Does HMDSO hydrolyze in water?

HMDSO has very low water solubility and is not generally treated as a readily hydrolyzing silane under ordinary aqueous contact. However, moisture limits can still be critical in high-purity silicone and electronic applications.

Is hexamethyldisiloxane flammable?

Yes. It is a highly flammable liquid with a flash point below room temperature. Ignition control, grounding, bonding, ventilation and compliant storage are required.

What is HMDSO used for in silicone production?

It can provide trimethylsiloxy terminal groups and help control chain length, molecular weight and viscosity in suitable PDMS manufacturing processes.

Can industrial-grade HMDSO be used in semiconductor production?

Not automatically. Semiconductor processes may require much tighter controls for metals, water, chloride, particles and nonvolatile residue. The grade and packaging must be qualified for the specific process.

Is HMDSO suitable for food, pharmaceutical or cosmetic use?

Suitability depends on the specific grade, formulation, intended use and applicable regional regulations. A general industrial grade should not be assumed to be food, pharmaceutical or cosmetic grade.

Request a Hexamethyldisiloxane Quotation

Contact AOZUN for hexamethyldisiloxane (MM/HMDSO), CAS No. 107-46-0.

Please include your required specification, application, quantity, packaging and destination. We can provide available product documents and discuss an appropriate grade for silicone manufacturing, surface-treatment or qualified electronic-material applications.