Controlled synthesis of siloxane polymers and siloxane-siloxane block copolymers with 3-chloropropyl groups pendant to the siloxane chain

Linear polysiloxanes bearing 3-chloropropyl groups pendant to the polymer chain and containing a vinyl functional group at one chain end were synthesized by anionic ring polymerizations of 2,4,6-tri(3-chloropropyl)-2,4,6-trimethylcyclotrisiloxane, 1, and 2-(3-chloropropyl)-2,4,4,6,6-pentamethylcyclotrisiloxane, 2, initiated with butyl lithium silanolate in tetrahydrofuran. The polymerizations led to high yields of polymers with narrow molecular weight distributions. The precise functionalizations of the polymers were performed by a termination method quenching the polymerization by dimethyl-vinylchlorosilane. Diblock copolymers AB of narrow molecular weight distributionand a high topological purity were obtained by the sequential anionic copolymerization of hexamethylcyclotrisiloxane D-3,with monomers 1 and 2.