Technology

What are Polysilazanes?

 

Polysilazanes are polymers consisting of alternating silicon and nitrogen atoms (Si-N) to form the basic backbone. Pendent groups, including hydrogen, alkyl, and/or aryl groups,  create an almost unlimited number of different chemical possibilities.

Polysilazanes are notable for high-temperature stability, resistance to oxidation, abrasion, and impact, and surface hardness (5H to 9H) making them resistant to scratch. They are resistant to many chemicals, weathering, and UV, have non-stick properties, and are easy to clean.

Polysilazanes are a chemical cousin of the more familiar silicones. They differ in that silicones have a backbone of alternating silicon/oxygen (Si-O) atoms instead of Si-N. Another significant difference is that polysilazanes are ceramic precursors—polymers which become ceramics after being fired at high temperatures.

Polysilazanes begin life like most plastics—as a liquid or a malleable solid which can be formed into useful solid items ranging from hairbrushes to auto bumpers. However, when heated to several hundred degrees, these materials begin to transform into high-quality advanced ceramics with a hardness approaching diamond and capable of withstanding temperatures up to 2000°C.

Polysilazanes were first reported in 1964 and have enjoyed a limited commercial success. Polysilazane utilization, however, especially in the U.S., has been hampered by high cost, boutique and exotic applications, unreliable commercial availability, and low production quantities.

Hathaway Advanced Materials is an Ohio (USA) corporation, a factor that will make polysilazane utilization more attractive to certain markets, including the U.S. military, aerospace, and defense industries.

Properties

Polysilazanes are colorless to pale yellow liquids or solids. They are not subject to vaporization, but upon heating they will begin to cross-link, forming higher molecular weight polymers. At about 100°C to 300°C, hydrogen and ammonia begin to evolve, accompanied by further cross-linking. Pyrolysis generally begins around 700°C-1200 °C. Polysilazanes are often characterized by a slight smell of ammonia.

Silanes are excellent coupling agents, adhesion promoters, dispersing/hydrophobing agents, and crosslinking agents. Polysilazanes share these properties and enjoy a number of properties which distinguish them from other polymers. Perhaps the most distinctive and useful of these are the following:

Bonding Properties

Polysilazanes—by virtue of their ability to react with moisture and polar surfaces—are capable of forming a tenacious bond with a wide range of materials, including metals, glass, wood, ceramics, and plastics, making them ideally suited for coating applications and composite binders.

Ceramic Precursor

Because of their silicon/nitrogen backbone, polysilazanes are readily pyrolyzed to form ceramic structures. Polysilazanes enjoy high “char” yields of silicon-based ceramic material, making them a convenient route for preparing ceramic products, many of which cannot be made through traditional ceramic processing methods. Fiber, coatings, composites, and structural products of silicon dioxide, silicon nitride, and silicon carbide ceramics can be readily manufactured from liquid precursor resins by this same approach, greatly simplifying manufacturing processes.

Functionalization

Polysilazanes are responsive to functionalization by a wide range of functional groups, making it possible to produce products such as mold releases, anti-graffiti coatings, and siloxane-like structures with excellent ‘easy-to-clean’ properties, while maintaining the ability to form powerful coating/substrate bonds. This same functionality can be incorporated into synthetic resins to create tightly-bonded top coats which when thermally cured can withstand temperatures of 400°C-600°C.

Hybrid and Copolymer Formation

Polysilazanes are well suited for forming hybrid polymers and copolymer formulations which incorporate many of the advantageous properties of the polysilazane into the resulting product. Functionalities such as UV resistance, UV transparency, fire retardancy, low electrical conductivity, water/moisture resistance, corrosion resistance, anti-fouling, and dozens of other functionalities can be achieved with polysilazane hybrids.

Applications

  • Coatings

  • Prepreg

  • Pre-ceramics

  • Ceramics

  • Composites

  • Hybrids

  • Additive Manufacturing (3-D Printing)

Forms available

  • Liquid (100% solids viscosities from low to highly viscous)
  • Solid (thermosetable soft, deformable solid)
  • Powder
  • Foam
  • Fiber & Film Former

Castable polymer-drived ceramic tile produced from Amber-EIC000

 

Contact us and let us know how our Amber-E™ polysilazanes products can help with your needs

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