Utility of a ruthenium metathesis catalyst for the preparation of end-functionalized polybutadiene

The polymerization of cyclooctadiene (COD) in the presence of an allylic difunctionalized chain transfer agent (1) by a ruthenium metathesis catalyst (Ru) was accomplished. Deprotection of the resulting acetate end-functionalized polybutadiene was performed, leading to commercially important 1,4-hydroxytelechelic polybutadiene (HTPBD) with number average functionalities close to 2.0. The polymerizations were performed at high monomer concentrations or in the absence of solvent, and the robust nature of Ru allowed the use of high monomer to catalyst ratios (∼0.01 mol % Ru relative to total olefin). Investigation of the metathesis of olefin alcohols with Ru showed that side reactions may complicate the use of these compounds as chain transfer agents in metathesis polymerizations. The kinetics of this Ru-catalyzed ring-opening metathesis polymerization with added chain transfer agent was also investigated.