Direct synthesis and characterization of crosslinked polysiloxanes via anionic ring‐opening copolymerization with octaisobutyl‐polyhedral oligomeric silsesquioxane and octamethylcyclotetrasiloxane

The crosslinked polysiloxanes were directly synthesized by anionic ring‐opening copolymerization of octaisobutyl‐polyhedral oligomeric silsesquioxane (POSS) as a multifunctional monomer with octamethylcyclotetrasiloxane (D 4 ) under base catalysts such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (Me 4 NOH) siloxanolate. The mechanism of anionic ring‐opening copolymerization of octaisobutyl‐POSS and D 4 was discussed and the influences of the polar additive N , N ‐dimethylacetamide on gelation time at different temperatures were investigated. The results of gel content and swelling ratio, GPC, solid‐state 29 Si and 13 C NMR, FTIR, XRD show that octaisobutyl‐POSS is reacted and most of the product is crosslinked. The DSC and TG results indicate that the crosslinked polysiloxanes exhibit distinct glass transition temperatures ( T g ) and excellent thermal stability. Compared to that under KOH siloxanolate, the crosslinked polysiloxane synthesized with Me 4 NOH siloxanolate has better preferable thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3848–3856, 2006