BRB Ethoxylated Organo-Functional Silanes (OFS): A Comparison Between Ethoxy and Methoxy - News

Ethoxylated organo-functional silanes are a specialized class of silane compounds modified with ethylene oxide (ethoxylate) chains and functional organic groups. These chemicals are widely used as surface modifiers, coupling agents, and dispersants in industries like coatings, adhesives, sealants, plastics, and personal care.

What are ethoxylated organo-functional silanes?

Structure: Typically, these molecules have:

A silane group (Si–OR): Capable of hydrolyzing and bonding with inorganic surfaces such as glass or metal;
An organo-functional group (e.g., amino, epoxy, methacryloxy): Reactive with organic polymers;
An ethoxylated segment (–(CH₂CH₂O)n–): Enhanced water solubility, flexibility, or surfactant behavior.

Most commonly used silanes are methoxy functional instead of ethoxy functional.

There are advantages on using ethoxylated OFS instead of methoxylated OFS. Please find the comparison table below.

COMPARISON TABLE

Feature

Methoxylated silanes

Ethoxylated silanes

Hydrolysis Rate

Faster due to smaller size and higher polarity

Slower, more controlled hydrolysis

Volatility

More volatile

Less volatile

Shelf Life

Usually shorter (more prone to premature hydrolysis)

Longer shelf stability in many cases

Solubility in Water

Better initial solubility, but may precipitate quickly

Often forms more stable emulsions or dispersions

Byproduct Alcohol

Methanol (toxic, flammable)

Ethanol (less toxic)

Application Use

Fast-bonding primers, glass treatments

Controlled-release coatings, dispersants

Reactivity

Very reactive – may need moisture control during storage

Moderate reactivity – easier handling

VOC Regulation Impact

Stricter due to methanol release

Slightly less strict (ethanol considered less hazardous)

Regulatory and Safety Note:

Methoxylated silanes: Upon hydrolysis, these silanes release methanol, a substance that is highly flammable and toxic. May trigger VOC and GHS hazard classifications;
Ethoxylated silanes: Release ethanol, considered safer but still flammable.

BRB Silanil^®919

Due to evolving legislation across several continents, the labeling requirements for methoxylated organo-functional silanes (OFS) have changed. These silanes release methanol as a byproduct during hydrolysis, a substance classified as a suspected carcinogen, which requires hazard labeling. In contrast with ethanol, the byproduct released by ethoxylated silanes, for which this is not the case.

BRB offers a range of ethoxylated organo-functional silanes:

ETHOXYLATED ORGANO-FUNCTIONAL SILANES

BRB product

Chemical name

CAS-number

Functionality/application

BRB Silanil^®505

N-(2-aminoethyl)-3-am inopropyl-triethoxy silane

5089-72-5

Diamino functional, very good adhesion promotor

BRB Silanil^®581

3-aminopropyltriethoxysilane aqueous solution

58160-99-9

Adhesion promotor, 40% in aqueous solution. Water-based coatings

BRB Silanil^®919

3-aminopropyltriethoxysilane

919-30-2

Adhesion promotor, organic and inorganic reactivity

BRB Silanil^®260

3-glycidoxypropyltriethoxysilane

2602-34-8

Coupling agent, as well organic as inorganic reactivity

BRB Silanil^®780

Vinyltriethoxysilane

78-08-0

Dispersing agent for fillers/polymer chain modifier. Water and abrasion improvement

BRB Silanil^®203

Methyltriethoxysilane

2031-67-6

Hydrophobic agent for inorganic surfaces (MS polymer and Solgel)

BRB Silanil^®294

N-octyltriethoxysilane

2943-75-1

Hydrophobic surface modifier for fillers, water repellent for construction chemicals

BRB Silanil^®403

Triethoxysilyl propyl tetrasulfide

40372-72-3

Coupling agent between inorganic filler and organic rubber

If you are new to our organization, please visit the BRB Silicones contact-us page to find the person responsible in your area.