Yttrium-Mediated Living Polymerization Opens the Door for Block Copolymers of Poly(β-hydroxybutyrate), Poly(lactic acid), and Highly Isotactic Poly(2-vinylpyridine)

We report the highly isoselective initiators for group-transfer polymerization (GTP) of 2-vinylpyridine (2VP), ring-opening polymerization of racemic β-butyrolactone (β-BL) and rac-lactide (LA) catalyzed by an yttrium complex bearing pyridine-2,6-bis(phenylenephenolate) ligands. The catalyst produces isotactic poly(2-vinylpyridine) (P2VP) with the highest isoselectivity (Pm up to 0.999) in a living GTP and mostly syndio-enriched (Pm = 0.25–0.44) polyhydroxybutyrate (PHB) and heterotactic rac-lactide (Pm = 0.34–0.38) via ring-opening polymerization (ROP) in a living fashion. A distinctive feature of these catalysts is their ability to block copolymerize 2VP, rac-β-BL, and in some cases rac-lactide. Thus, a wide range of P2VP-b-PHB diblock and in some cases P2VP-b-PHB-b-PLA triblock copolymers were obtained and some of them used to produce stable gold nanoparticles solutions.