Polylactide (PLA) is a leading bio-derived polymer, in this field there is considerable attention and interest in stereoblock PLA due to its improved thermal and mechanical properties. Currently, stereoblock PLA can be prepared from racemic lactide using aluminum salen catalysts, however, these species are slow and require high catalyst loadings. This presentation will introduce a series of new Group 3 and lanthanide catalysts, based on coordination complexes of phosphasalen ligands, as an alternative to aluminum salens.[1] The new catalysts show excellent rates, high degrees of iso-selectivity (Pi: 0.85, 298 K) and high degrees of polymerization control. The presentation will focus on our investigations into the factors which influence and control the polymerization kinetics and stereoselectivity. Our hypotheses regarding control will be presented, together with strategies to further improve stereoselectivity. The thermal properties of the stereoblock PLA will also be presented.[1] Bakewell, C.; Thi-Phuong-Anh, C.; Le Goff, X. F.; Long, N. J.; Auffrant, A.; Williams, C. K. Organometallics 2013,  32, 1475-1483. Bakewell, C.; Cao, T.-P.-A.; Long, N.; Le Goff, X. F.; Auffrant, A.; Williams, C. K. J. Am. Chem. Soc. 2012,  134, 20577-20580

Stereoblock polylactide: New, highly active, and iso-selective catalysts based on group 3/lanthanide phosphasalen complexes

248th National Meeting (2014)

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