Controlled Anionic Polymerization of Hexamethylcyclotrisiloxane. Model Linear and Miktoarm Star Co- and Terpolymers of Dimethylsiloxane with Styrene and Isoprene

Controlled polymerization of hexamethylcyclotrisiloxane was achieved by carrying out the polymerization first at room temperature to about 50% conversion and then at −20 °C until complete conversion in order to avoid side reactions. The poly(dimethylsiloxane)s produced show narrow molecular weight distributions ( M w / M n ≤ 1.1). Using this approach, a model linear triblock copolymer PS- b -PDMS- b -PS, as well as 3-miktoarm star co- and terpolymers of the (PDMS)(PS) 2 and (PDMS)(PS)(PI) type, where PS is polystyrene, PI is polyisoprene, and PDMS is poly(dimethylsiloxane), have been prepared.