ABSTRACT: The dimethylaluminum compounds {3-tBu-2-(O)C6H3CH=N-R}AlMe2 [R=C6H5 (1); 2,6- iPr2C6H3 (2); C6F5 (3)] were used as initiators in the ring-opening polymerization (ROP) of ε-capro- lactone, L-lactide, and D,L-lactide. Compound 3, in combination with 1 equiv of methanol, exhibited a living behavior in the ROP of the cyclic esters. Such a feature allowed the preparation of poly(D,L-lactide-block- ε-caprolactone) and poly(L-lactide-block-ε-caprolactone) copolymers. Random copolymers of ε-caprolactone and L-lactide and of ε-caprolactone and D,L-lactide were also synthesized by compound 3. NMR and DSC characterization confirmed a highly random structure of these copolymers, even in the absence of transesterification reactions. All the materials, characterized by GPC, showed high molecular weight and narrow molecular weight distributions.
Living Ring-Opening Homo- and Copolymerization of epsilon-Caprolactone and L- and D,L-Lactides by Dimethyl(salicylaldiminato)aluminum Compounds
ANNUNZIATA, LIANA;PELLECCHIA, Claudio
2009
Abstract
ABSTRACT: The dimethylaluminum compounds {3-tBu-2-(O)C6H3CH=N-R}AlMe2 [R=C6H5 (1); 2,6- iPr2C6H3 (2); C6F5 (3)] were used as initiators in the ring-opening polymerization (ROP) of ε-capro- lactone, L-lactide, and D,L-lactide. Compound 3, in combination with 1 equiv of methanol, exhibited a living behavior in the ROP of the cyclic esters. Such a feature allowed the preparation of poly(D,L-lactide-block- ε-caprolactone) and poly(L-lactide-block-ε-caprolactone) copolymers. Random copolymers of ε-caprolactone and L-lactide and of ε-caprolactone and D,L-lactide were also synthesized by compound 3. NMR and DSC characterization confirmed a highly random structure of these copolymers, even in the absence of transesterification reactions. All the materials, characterized by GPC, showed high molecular weight and narrow molecular weight distributions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
