Aluminum amine-bis(phenolate) complexes for ring-opening polymerization of rac-lactide and ε-caprolactone

Edward Cross, Gayan Tennekone, Andreas Decken, Michael Shaver

Research output: Contribution to journalArticlepeer-review

Abstract

Five aluminum-based amine-bis(phenolate) complexes, three of them novel, with variation of the pendant donor arm were synthesized in excellent yields, and characterized by NMR spectroscopy and X-ray crystallography. The quantitative conversion of the aluminum alkyl species to the corresponding benzyl alkoxide was achieved by the addition of 1 mol eq. of benzyl alcohol, and was confirmed by 1H NMR spectroscopy. The aluminum alkoxides were excellent mediators for the ring-opening polymerization (ROP) of rac-lactide, yielding atactic poly(lactic acid), having excellent correlation between theoretical and calculated molecular weights accompanied by narrow molecular weight distributions. ROP of ε-caprolactone by the aluminum alkoxides showed modest control at 50°C in toluene, but much greater control was achieved when polymerizations were conducted at 25°C, with narrower molecular weight distributions observed in some cases. A relationship between the complex pendant donor arm and the resulting activity in the ROP of both rac-lactide and ε-caprolactone is discussed.
Original languageEnglish
Pages (from-to)79-86
JournalGreen Materials
Volume1
Issue number2
Early online date23 Aug 2012
DOIs
Publication statusPublished - 2013

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