Controlled ring-opening polymerization of lactide by bis-sulfonamide/amine associations: Cooperative hydrogen-bonding catalysis

The bis-sulfonamide m-C₆H₄(SO₂NHPh)₂ efficiently promotes the ring-opening polymerization of lactide when combined with tertiary amines, such as N,N-dimethylaminopyridine. Polylactides of controlled molecular weights (Mn up to 17,700 g mol⁻¹) and very narrow molecular weight distributions (Mw/Mn < 1.11) are obtained under mild conditions and in a living fashion. The reaction takes place through a bifunctional mechanism involving activation of both the alcohol and the monomer. Modulation of the sulfonamide component supports cooperative dual hydrogen-bonding of lactide involving the two (SO₂NHAr) moieties.