Functional polylactide by cationic ring-opening copolymerization of lactide with epoxides

Sequential and simultaneous cationic copolymerizations of lactide with commercial functional epoxides: allyl glycidyl ether, glycidyl propargyl ether, and epichlorohydrin, catalyzed by a protic acid in a one-pot process were studied. Block and gradient polylactide-based medium-molecular-weight copolymers with several alkene, alkyne, or chloromethyl groups at one chain end or with gradient distribution along the polymer chain were successfully synthesized, as proven by 1H NMR, SEC, and MALDI TOF analyses. Functional polylactides were further subjected to thiol-ene addition, cycloaddition of azide, or reaction with tertiary amine, respectively, to demonstrate the reactivity of the introduced functional groups.