Thermal Transitions and Reaction Kinetics of Polyhederal Silsesquioxane Containing Phenylethynylphthalimides (Preprint)

摘要

Thermal transitions and reaction kinetics of polyhedral oligomeric silsesquioxane (POSS) with a phenylethynylphthalimide (PEPI) moiety were investigated. Specifically, this study was aimed to understand the influence of the POSS periphery, types of spacer group in between the PEPI and the SiO core, architecture of PEPI arrangement with respect to the SiO core, and number of PEPI groups per cage on the thermal transitions and the crosslinking reaction of phynylethynyl. PEPI-POSS compounds with a phenyl periphery show higher melting temperatures as compared to those with isobutyl peripheries. PEPI-POSS compounds with isobutyl peripheries show a higher phenylethynyl reaction rate than those PEPIPOSS compounds with phenyl peripheries. Changing the spacer group from propyl to phenyl increases the melting transition temperature as well as higher heat of fusion at melting; however the more rigid phenyl spacer enables the PEPI-POSS form a higher degree of crystallinity upon cooling. The more rigid phenyl spacer also initiates the polyene reactions at lower temperatures, but at higher temperatures, some reaction pathways become restricted leading to a lower overall extent of reaction.