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Immortal Ring-Opening Polymerization of Lactides with Super High Monomer to Catalyst Ratios Initiated by Zirconium and Titanium Complexes Containing Multidentate Amino-bis(phenolate) Ligands

Abstract

Zirconium complexes (L2Zr, L = -OC6H2-4-R1-6-R2-2-CH2-N[(CH2)3-N(CH2CH2)2O]-CH2-4-R1-6-R2-C6H2O-, R1 = Me, R2 = tBu, complex 1; R1 =R2 = tBu, complex 2) containing two symmetrical amino-bis(phenolate) ligands were prepared. Moreover, titanium complexes (LTi(OiPr)2, L = -OC6H2-4-R1-6-R2-2-CH2-N[(CH2)3- N(CH2CH2)2O]-CH2-4-R1-6-R2-C6H2O-,R1 = Me, R2 = tBu, complex 3; R1 = R2 = tBu, complex 4) based on symmetrical amino-bis(phenolate) ligands were synthesized. These complexes were characterized by 1H, 13C NMR spectroscopy and elemental analyses. The solid state structure of complex 2 and complex 3 was determined by X-ray diffraction. Complexes 1, 2, 3, 4 were highly active initiators for the ring-opening polymerization of L-lactide (L-LA) and rac-lactide (rac-LA). Experimental results show that complexes 1 and 2 are highly active and excellent catalysts for immortal ring-opening polymerization (iROP) of L-lactide and rac-lactide in the melt. The monomers to complex ratio reached to 200 000/1, which is the highest feeding molar ratio of lactide, to the best of our knowledge so far. The turnover frequency (TOF) reached to 6593 h-1, and the polymerization proceeded smoothly, even in an air environment.

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Publication details

The article was received on 10 Feb 2017, accepted on 18 May 2017 and first published on 18 May 2017


Article type: Paper
DOI: 10.1039/C7NJ00483D
Citation: New J. Chem., 2017, Accepted Manuscript
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    Immortal Ring-Opening Polymerization of Lactides with Super High Monomer to Catalyst Ratios Initiated by Zirconium and Titanium Complexes Containing Multidentate Amino-bis(phenolate) Ligands

    B. Wang, H. Zhao, L. Wang, J. Sun, Y. Zhang and Z. Cao, New J. Chem., 2017, Accepted Manuscript , DOI: 10.1039/C7NJ00483D

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