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n-Hexyltriethoxysilane: A Versatile Silane Coupling Agent

n-Hexyltriethoxysilane (CAS 18166-37-5) is a silane coupling agent that can be used to modify the surface properties of various materials, such as metals, glass, ceramics, polymers and fillers. It has a molecular formula of C12H28O3Si and a molecular weight of 248.44.

Structure and Properties

n-Hexyltriethoxysilane has a linear hexyl group attached to a silicon atom, which is bonded to three ethoxy groups. The hexyl group provides hydrophobicity and compatibility with organic solvents, while the ethoxy groups can hydrolyze and form silanol groups that can react with hydroxyl groups on the surface of substrates.

The structure of n-Hexyltriethoxysilane is shown below:

    CH3CH2CH2CH2CH2CH2-Si-(OCH2CH3)3

n-Hexyltriethoxysilane is a clear, colorless to almost colorless liquid with a boiling point of 115 °C and a density of 0.86 g/mL at 25 °C. It has a refractive index of 1.408 and a flash point of 95 °C. It is soluble in most organic solvents, such as alcohols, ethers, ketones and hydrocarbons, but insoluble in water. It is sensitive to moisture and can hydrolyze slowly in the presence of water or humidity.

Applications

n-Hexyltriethoxysilane can be used as a coupling agent to improve the adhesion, dispersion, compatibility and durability of various materials. Some of the applications are:

  • Coating: n-Hexyltriethoxysilane can be used to modify the surface of metal substrates, such as aluminum, copper, iron and steel, to improve the corrosion resistance, adhesion and gloss of organic coatings. It can also be used to modify the surface of glass substrates, such as glass fibers and beads, to improve the hydrophobicity, scratch resistance and optical properties of coatings.
  • Polymer: n-Hexyltriethoxysilane can be used to graft onto the surface of polymers, such as polyethylene, polypropylene, polystyrene and polyvinyl chloride, to improve the thermal stability, mechanical strength, flame retardancy and compatibility with fillers. It can also be used to crosslink polymers, such as silicone rubber and polyurethane, to enhance the elasticity, flexibility and durability.
  • Filler: n-Hexyltriethoxysilane can be used to treat the surface of fillers, such as silica, alumina, calcium carbonate and talc, to improve the dispersion, rheology and bonding with polymers. It can also be used to reduce the moisture absorption and agglomeration of fillers.

Safety and Handling

n-Hexyltriethoxysilane is classified as a hazardous substance according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). It may cause skin irritation, eye irritation and respiratory tract irritation. It may also be harmful if swallowed or inhaled. Therefore, it should be handled with care and appropriate personal protective equipment (PPE), such as gloves, goggles and respirator. It should be stored in a cool, dry and well-ventilated place away from heat sources, sparks and flames. It should also be kept away from water or moisture sources to avoid hydrolysis.