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A variety of organocatalysts has been surveyed in the ring opening polymerization of trimethylene carbonate. Excellent control was found for several of these catalysts yielding well-defined polycarbonates with molecular weights up to 50 000 g mol-1, polydispersities below 1.08, and high end-group fidelity. Melt or bulk polymerization was accomplished without loss of control of molecular weight or polydispersity, and random ester−carbonate bulk polymerizations were also demonstrated. Furthermore, by combining disparate polymerization techniques using bifunctional initiators, the mild polymerization conditions allow for the preparation of new block copolymers. Hydrogen-bond activation of monomer and initiator/propagating species is proposed as the underlying mechanism, which can be tuned to mitigate adverse side reactions. [ABSTRACT FROM AUTHOR]

Metallo-supramolecular diblock copolymers consisting of a polystyrene (PS) block connected to a poly(ethylene oxide) (PEO) block by a bis(terpyridine)ruthenium complex (PS 20-[Ru]-PEO y) were used to prepare aqueous micelles. The length of the PS block was kept constant, while two PEOs of different molecular weight were used. The resulting hydrated micelles and aggregates were characterized by a combination of cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering measurements. The results were compared to those obtained for a covalent counterpart (PS 22- b-PEO 70). Cryogenic transmission electron microscopy allowed visualization of the PS core of the micelles. Moreover, the aggregates result from clustering of individual micelles. [ABSTRACT FROM AUTHOR]