One-pot organocatalysis of diacrylates to functional polyesters for toughening polylactide

Conventional chain-growth polymerization of acrylic monomers or diacrylics leads to non-degradable vinyl polymers or crosslinked networks, while existing step-growth polymerization affords saturated or main-chain unsaturated polyesters, hindering post-functionalization. Here, we introduce a hydrogen-transfer polymerization (HTP) strategy via the trialkylphosphine-catalyzed head-to-tail C-C coupling between the α- and β-positions of two vinyl groups of diacrylates with exclusive regioselectivity, producing unsaturated polyesters with side-chain double bonds that can undergo the subsequent thiol-Michael click reaction in a one-pot fashion with the carryover phosphine from the HTP step. The resulting hydroxyl-functionalized polyesters serve as macroinitiators for the efficient synthesis of densely grafted poly(l-lactide) (PLLA) bottlebrush polymers. Such bottlebrush polymers markedly toughen the otherwise brittle PLLA (by ∼10×), while not only uniquely preserving high melting temperature and crystallinity of PLLA but also synergistically increasing the PLLA crystallization rate.