Rational design of silsesquioxane-based polymers

Silsesquioxane-based polymers are a technologically important class of materials that is continuing to undergo rapid development. The recent synthesis of monomeric reagents based on polyhedral oligomeric silsesquioxanes (POSS) now enables the synthesis of silsesquioxane-based polymers via non sol-gel routes. POSS reagents containing only one or two reactive functionalities enable the preparation of silsesquioxane polymers with well-defined linear polymeric chains. The preparation of linear POSS-based copolymers with bead, pendant, and triblock architectures will be described. The synthesis, characterization, and properties for a family of POSS-siloxane copolymers will be presented in detail. These materials possess high thermal stabilities, indefinite shelf life, and mechanical properties which range from brittle to flexible plastics. Insights into extension of this approach to other POSS-copolymer compositions will also be discussed.