In Phase 1, CRG demonstrated the feasibility of a novel approach to prepare cyanate ester based elastomers. This approach polymerizes in-situ siloxane within a reactive elastomer precursor matrix in order to achieve an elastomeric material with highly tunable and desired mechanical properties. This methodology shows great potential in materials development for applications such as space deployable structures, space seals, and aeroshells. Using this methodology CRG was able to show that elastomeric cyanate ester materials having a vary broad range of thermal and mechanical properties could be formulated using a relatively small amount of CRG's synthesized monomers and other low-cost, commercially available components, such as low-cost, low molecular weight silicone materials. The cyanate ester elastomer materials exhibited excellent thermal stability, maintaining their elastomeric properties to temperatures below -100 C and as high as 300 C. The proposed Phase 2 effort will leverage Phase 1 results and CRG's other extensive R&D in elastomeric material technologies to bring the methodology to readiness for transition to operational use.