Heterogeneous catalyzed copolymerization of octamethylcyclotetrasiloxane with 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane

For the introduction of vinyl groups at the Si atom of the siloxanic chain, copolymerization of octamethylcyclotetrasiloxane (D-4) with 1,3,5;7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (V-4) was performed. Vionit CS-34 C, a styrene-divinylbenzene copolymer with SO3H groups, was used as catalyst. To estimate the reactivity ratios by the Mayo-Lewis Scheme, the reaction was stopped at maximum 10% conversion. The probabilities of triads existence were calculated from Si-29 NMR, then the microstructure parameters of the formed copolymers were estimated. It was noticed that the dimethylsiloxy units have a higher tendency to form blocks.