Oligomeric Heterogeneous Double Metal Cyanide Catalyst for One‐pot Ring‐Opening Polymerization

Abstract

AbstractA series of efficient oligomeric zinc and cobalt‐based double metal cyanide (DMC) catalysts was prepared using Ethylenediaminetetracetic acid (EDTA) as an organic complexing agent (CA) and tested for ring‐opening polymerization (ROP) of propylene oxide (PO) to synthesize polyether polyols (PPG). The complex formation of EDTA with Zn and cyanide (CN−) with Zn surface and morphology of the DMC catalyst were confirmed by PXRD, FTIR, SEM, and UV‐Vis. Furthermore, the13C‐CP MAS spectroscopy showed an integral ratio of 3.2 : 1 for the bound and free carboxyl group of EDTA in the catalyst, respectively. The maximum yield (>98 %) of PPG with turnover frequency (TOF) of 9625 h−1was obtained with controlled PDI (1.1) in only 1 h with 1330 g mol−1Mw, 0.009 meq g−1unsaturation number, and 8.1 mg‐KOH g−1OH value at optimized reaction condition (Catalyst amount=0.015 g, Time=1 h, Temperature=105 °C, Pressure=5 bar, PO : PEG‐600=40 : 1). The ROP showed first‐order kinetics behavior by1H NMR spectroscopy with proposed coordination mechanism.