Silacyclobutanes polycarbosilanes

The polycarbosilane [(CiyisSi -CsH ZrCy, 159, was prepared from the ring-opening polymerization of the spirocyclic silacyclobutane-bridged monomer (Ciy Si -CsH ZrCy 158, with Karstedt s catalyst (Scheme 2.42).229 The ring opening of the zirconocene ring was also attempted, but polymerization could not occur under the reaction conditions. Both 158 and 159 showed some catalytic activity for ethylene polymerization. 

The platinum-catalyzed or thermal ring opening polymerization of the substituted silacyclobutane monomers yields linear polycarbosilanes. The platinum-catalyzed hydrosilations of the AB (allyl) and AB2 (diallyl) monomers yield linear and hyperbranched polycarbosilanes, respectively. A wide range of random copolymers are readily available from polymerization of mixtures of the silacyclobutane or AB and AB2 monomers. The preparation of random copolymers is often of interest for achieving desired physical properties. 

Abstract The presented paper is a summary of our results on synthesis and polymerization of silyl-containing norbomenes and norbomadienes via ring-opening metathesis polymerization (ROMP) and addition processes as well as ring-opening polymerization (ROP) of silacyclobutanes and disilacyclobutanes. The synthesis of heterochain and carbochain polymer families with regularly varied substituents at Si atom and various number and location Si(CH3)3-substituents has been realized. Systematic study of gas transport parameters of polycarbosilanes series of different classes allowed us to find out real eorrelations between features of chemical polymer structure and its gas separation eharacteristics. 

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