Volume 10, Issue 18 p. 3547-3556
Full Paper

Highly Active N,O Zinc Guanidine Catalysts for the Ring-Opening Polymerization of Lactide

Pascal M. Schäfer

Pascal M. Schäfer

Institut für Anorganische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany

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Martin Fuchs

Martin Fuchs

Institut für Anorganische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany

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Andreas Ohligschläger

Andreas Ohligschläger

Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany

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Ruth Rittinghaus

Ruth Rittinghaus

Institut für Anorganische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany

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Dr. Paul McKeown

Dr. Paul McKeown

Department of Chemistry, University of Bath, ClavertonDown, Bath, BA2 7AY UK

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Dr. Enver Akin

Dr. Enver Akin

Fakultät für Naturwissenschaften, Department Chemie, Universität Paderborn, Warburger Strasse 100, 33098 Paderborn, Germany

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Maximilian Schmidt

Maximilian Schmidt

Institut für Anorganische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany

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Dr. Alexander Hoffmann

Dr. Alexander Hoffmann

Institut für Anorganische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany

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Prof. Dr. Marcel A. Liauw

Prof. Dr. Marcel A. Liauw

Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany

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Dr. Matthew D. Jones

Dr. Matthew D. Jones

Department of Chemistry, University of Bath, ClavertonDown, Bath, BA2 7AY UK

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Prof. Dr. Sonja Herres-Pawlis

Corresponding Author

Prof. Dr. Sonja Herres-Pawlis

Institut für Anorganische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany

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First published: 05 August 2017
Citations: 64

Graphical Abstract

Fast and robust! Four fast robust ring-opening polymerization (ROP) catalysts polymerize lactide in high yields and good molar masses with potential for industrial application. All four complexes combine robustness against impurities in the lactide with high polymerization rates, and they represent the fastest robust lactide ROP catalysts to date. End-group analysis was performed to clarify the mechanism.

Abstract

New zinc guanidine complexes with N,O donor functionalities were prepared, characterized by X-Ray crystallography, and examined for their catalytic activity in the solvent-free ring-opening polymerization (ROP) of technical-grade rac-lactide at 150 °C. All complexes showed a high activity. The fastest complex [ZnCl2(DMEGasme)] (C1) produced colorless poly(lactide) (PLA) after 90 min with a conversion of 52 % and high molar masses (Mw=69 100, polydispersity=1.4). The complexes were tested with different monomer-to-initiator ratios to determine the rate constant kp. Furthermore, a polymerization with the most active complex C1 was monitored by in situ Raman spectroscopy. Overall, conversion of up to 90 % can be obtained. End-group analysis was performed to clarify the mechanism. All four complexes combine robustness against impurities in the lactide with high polymerization rates, and they represent the fastest robust lactide ROP catalysts to date, opening new avenues to a sustainable ROP catalyst family for industrial use.

Conflict of interest

The authors declare no conflict of interest.