Silsesquioxanes with Phenylethynyl Terminated Oligoimides

The incorporation of cage-like silsesquioxanes (SQ) to form polymers has demonstrated property enhancements in areas such as: thermal and mechanical characteristics, flame retardance, dielectric properties, and oxidative resistance. However, with most of hybrids investigated, the attached SQs are pendant with respect to the reaction site, thus mechanical performance did not take full advantage about the rigid nature of SQ core. A recently developed class of these nano-structured, cage-like silsesquioxanes, formally known as double decker silsesquioxanes (DDSQ), offers the opportunity to form hybrids with the SQ cage as the bridge between multiple reaction sites. This advancement provided a unique opportunity to form networks with Si-O core connecting those reaction junctions, which may positively affect the mechanical performance on thermosetting polymers. It was discovered during the capping reaction, these functionalized DDSQs generate cis and trans isomers with respect to the 3D Si-O core. In addition meta- and para- functional groups may be used to form hybrid reacting monomer mixture containing six different isomers. Depending on the relative ratio of isomers in the mixture, viscosity can be well controlled with no effect on the reaction mechanism and kinetics. Therefore, it is expect to improve the processing of high temperature oligoimide resins while improve thermoxidative stability (TOS) of organic networks. Synthesis details, different methods of incorporating DDSQ mixtures and their TOS performance were presented.