Anionic copolymerization of α,ω-dihydroxyoligodimethylsiloxane with organocyclosiloxanes

The anionic copolymerization of α,ω-dihydroxyoligodimethylsiloxane with 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane in the presence of potassium poly(dimethylsiloxane)-α,ω-diolate has been investigated by 29 Si NMR spectroscopy. It has been established that the formation of copolymer structure strongly differs from that known for the copolymerization of two different cyclosiloxanes or a cyclosiloxane with linear trimethylsiloxy-terminated oligo(dimethylsiloxanes). It is assumed that the observed copolymerization process is governed by the combined effects of proton-cation exchange and disproportionation involving terminal siloxanol and silanolate groups. A scheme describing changes in the copolymer microstructure has been proposed.