Living 3,4-Isoselective (Co)polymerization of Biobased β-Farnesene Catalyzed by Phosphine-Functionalized Fluorenyl Rare-Earth Metal

With an objective to reduce petrochemical dependency, synthesis of biobased polymers from renewable feedstocks has been widely investigated. In this study, we report that living and highly 3,4-isoselective polymerization of the biobased monomer beta-farnesene (100% 3,4-, >99% mmmm) can be realized at room temperature using a phosphine-functionalized fluorenyl-ligated yttrium catalytic system with ultrahigh activity. Detailed investigations suggested that the coordinated phosphine group plays a pivotal role in the high regio- and stereoselectivity of 1-Y-catalyzed beta-farnesene polymerization, and the density functional density (DFT) calculation offered important insights into the 3,4-isoselectivity. Additionally, block copolymers featuring rigid 3,4-isospecific polyisoprene blocks and amorphous 3,4-isospecific polyfarnesene blocks were successfully prepared. The morphology and mechanical properties of these elastomeric copolymers were studied by using atomic force microscopy and stress-strain experiments, respectively.