Tailor-Made n-Steroblock Copolymers of Poly(lactic acid) by a Truly Living Polymerization Catalyst

Poly(lactic acid) (PLA) is a biodegradable polymer prepared by the catalyzed ring opening polymerization of lactide. An ideal catalyst should enable a sequential polymerization of the lactide enantiomers to afford stereoblock copolymers with predetermined number and lengths of blocks. We recently introduced a new family of magnesium based catalysts that combine extremely high activity with a true-living nature, which gives access to PLA materials of unprecedented microstructures. Full consumption of thousands of equivalents of L-LA within minutes gave PLLA of expected molecular weights and narrow molecular weight distributions. Precise PLLA-b-PDLA diblock copolymers having block lengths of up to 1000 repeat units were readily prepared within 30 min, and their thermal characterization revealed a stereocomplex phase only with very high melting transitions and melting enthalpies. The one pot sequential polymerization was extended up to precise hexablocks having ‘dialed-in’ block lengths which have not been reported before. These truly-living catalysts may open the way to next-generation PLA-based materials having vast potential for applications in material science.

References:

Rosen, T; Goldberg, I; Venditto, V; Kol, M. In preparation

Rosen, T; Goldberg, I; Venditto, V; Kol, M. J. Am. Chem. Soc. 2016, 138, 12041-12044