Direct synthesis and characterization of cross-linked 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 D4 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 Si-29 and C-13 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 Me4NOH siloxanolate has better preferable thermal stability. (c) 2006 Wiley Periodicals, Inc.