Definition - What does Polysiloxanes mean?

Polysiloxanes, or polymerized siloxanes, are a polymer with a silicon-oxygen backbone. Its chemical formula is (R2SiO)n , where R is usually methylsiloxanes (CH3), although it can be H or alkyl or aryl group. Polysiloxane has shown greater resistance to the effects of UV radiation than organic polymers containing a carbon-carbon backbone. Polysiloxanes can be oils, greases, rubbers or plastics depending on molecular weight.

Polysiloxanes exhibit:

  • Superb abrasion and corrosion resistance
  • Strong chemical resistance
  • Anti-graffiti properties
  • Resilience to dirt pickup
  • Low VOCs

Corrosionpedia explains Polysiloxanes

Polysiloxanes refer to a wide range of fluids, resins, or elastomers, which are made from polymerizations of siloxanes. The siloxanes consist of alternating silicon and oxygen atoms.

Some useful properties of polysiloxanes include:

  • Flexibility
  • Chemical inertness
  • Permeability to gases
  • Resistance to water and oxidation
  • Low glass transition temperature
  • Low surface energy

These properties make polysiloxanes suitable for a wide range of commercial applications, such as:

  • Electrical (e.g., insulation),
  • Electronics (e.g., coatings),
  • Household (e.g., sealants for cooking apparatus),
  • Automobile (e.g., gaskets), airplane (e.g., seals),
  • Textiles/paper (e.g., coatings)
  • Lubricating greases

Polysiloxane coatings are very useful in industrial protective and maintenance coatings. They have excellent aesthetic weathering attributes. There are three key categories of polysiloxane coatings:

  • Inorganic Polysiloxanes: Cured by hydrolytic polycondensation. These resist temperatures up to 1,400°F (760°C) and have excellent solvent resistance.
  • Epoxy-Polysiloxane Hybrids: Cured by both hydrolytic polycondensation and conventional epoxy-amine mechanisms, these coatings create weather and corrosion-resistant hybrids. They provide superior resistance to weathering over other conventional epoxy coatings.
  • Acrylic-Polysiloxane Hybrids: These produce a low VOC, highly weatherable topcoat.

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