Branched and functionalized polybutadienes by a facile two-step synthesis

Anionic polymerization was used to prepare silane-endfunctionalized polybutadiene macromonomers with different molecular weights ranging from 9 000 to 34 000 g center dot mol(-1). These were polymerized by a hydrosilylation reaction in bulk to obtain branched polymers, using Karstedt's catalyst. Surprisingly, the addition of monofunctional silanes during the polymerization showed only a minimal effect concerning the degree of polymerization. Furthermore, it was possible to introduce a variety of functional silanes without increasing the overall number of reaction steps by a convenient AB(2)+ A type "pseudocopolymerization" method. All branched polymers were analyzed by SEC, SEC-MALLS, SEC-viscosimetry. H-1 NMR spectroscopy, and DSC concerning their branching ratio. The branching parameters for the branched polymers exhibited similar characteristics as for hyperbranched polymers obtained from conventional AB(2) monomers. Detailed kinetic studies showed that the polymerization occurred very rapidly in comparison to the hydrosilylation polymerization of classical AB(2) type carbosilane monomers.