In Situ versus Isolated Zinc Catalysts in the Selective Synthesis of Homo and Multi-block Polyesters

Weronika Gruszka, Leah C Walker, Michael Shaver, Jennifer A Garden

Research output: Contribution to journalArticlepeer-review

Abstract

The in situ generation of metal-alkoxide complexes is a common initiation method in cyclic ester ring-opening polymerisation. Yet this method is often a “black box”, where the species so generated are assumed to be the same as the isolated complex. We now demonstrate that an isolated Zn-benzoxide catalyst gives a remarkable reactivity enhancement in lactide ROP, with kobs values 10 times higher than the in situ generated analogue. The dinuclear zinc catalyst, built using the Trost ProPhenol ligand, offers these excellent activities and good control over homopolymerisation of multiple cyclic esters (rac-lactide, ε-caprolactone and rac-β-butyrolactone). The stability of this isolated catalyst also controls chain exchange and back-biting, allowing for one-pot synthesis of multi-block polyesters without loss of activity, selectivity and control. To the best of our knowledge, this is the first catalyst reported for the selective preparation of block terpolymers of ε-CL, rac-LA and rac-β-BL.
Original languageEnglish
JournalMacromolecules
Publication statusAccepted/In press - 5 May 2020

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