Description: NRL has developed a new class of polymeric materials with remarkable resistance to heat, dielectric breakdown, and oxidation at high temperatures. For applications that demand high temperature resistance coupled with greater strength, these polymers can be easily transformed into ceramics with extreme thermal and oxidative stability. NRL's new polymeric materials, which are made from resins derived from carboranes and either vinyl or acetylene siloxanes, can resist temperatures up to 510°C (950°F) in air, and are highly resistant to chemical attack. They can be molded, injected, or coated, and are also highly adhesive. The acetylenic variety is thermally cured at 200°C, whereas the vinylic type cures at room temperature. However, once cured, the hardness and strength of the materials can be substantially increased by thermally converting them to a novel lightweight ceramic that can withstand temperature in air of at least 1500°C. While the network polymers possess all of the inherent siloxane characteristics, they are highly insulating in nature, with exceptional high-temperature dielectric stability under high voltages.

Advantages/Features Include:

  • Organic unsaturated-containing poly (carboranylenesiloxanes) materials are viscous liquids at room temperature and are easily processed into shaped confi gurations.
  • Opportunity for conversion of the materials into network polymers at room temperature or at elevated temperatures gives a broad range of applications for these materials.
  • Structural characteristics of these materials can be easily controlled by the dilution of the crosslinking density in the materials.
  • Plastics, films, and fibers can be formulated from the liquid precursors.
  • Structural components can be readily fabricated by cost-effective methods such as resin transfer molding, resin infusion molding, and fi lament winding.

Applications Include:

  • Aerospace - engine applications
  • Insulative coatings for high-performance organic and metal fibers
  • High-temperature adhesives
  • Polymeric precursors for nanomaterials
  • High-temperature dielectrics for electronic applications
  • Repair of space vehicles while in orbit
  • Neutron absorbers – nuclear storage containers and shields

References:

  • "Formation of Elastomeric Network Polymers from Ambient Heterogeneous Hydrosilations of Carboranylenesiloxane and Branched Siloxane Monomers", J. Polym. Sci.: Part A: Polym. Chem., 44, 147 (2006)
  • "Dependence of Thermal Properties on Copolymer Sequence in Diacetylene-Containing Polycarboraneylenesiloxanes", Chem. of Mater., 16, 3162 (2004)
  • "The Effects of Concentration Dilution of Cross-linkable Diacetylenes on the Plasticity of Poly(m-Carborane-Disiloxane-Diacetylene)s", J. Mater. Chem., 13, 1652 (2003)

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