Synthesis and characterization of heptacyclic laddersiloxanes and ladder polysilsesquioxane

As a continuation of our previous studies on thermostable materials, heptacyclic laddersiloxanes and ladder polysilsesquioxane were synthesized. The first heptacyclic laddersiloxanes were obtained by chlorination of pentacyclic laddersiloxanes prepared using our stereocontrolled synthesis procedure; thereafter, the heptacyclic laddersiloxanes were made to react with disiloxanediol. Ladder polysilsesquioxane was obtained from cis-trans-cis-tetrabromotetramethylcyclotetrasiloxane by spontaneous hydrolysis and dehydration. The spectral and thermal properties of these new compounds were investigated. It was observed that the thermal stability of these compounds increases with the ring number. Copyright (C) 2010 John Wiley & Sons, Ltd.