Construction of Ultralow-Molecular-Weight CO₂–Polyols with Self-Catalytic Performance in Polyurethane Preparation

Abstract

An aminic CO 2 -based poly(ether-carbonate) polyol has been successfully synthesized by CO 2 /propylene oxide copolymerization with the primary aromatic amine as the initiator under a double metal cyanide (DMC) complex catalyst. The weak basicity and coordination ability of amine initiators are conducive to enhancing the copolymerization productivity and catalytic activity. A branched aminic CO 2 -polyol has been constructed with catalytic efficiency up to 4.1 kg g −1 DMC using the diamine of 4,4′-methylene-bis(2-chloroaniline) as the initiator, whose average −OH functionality can be facilely tuned in the range of 2.4−3.6. The evolution of the number and length of multiarm polymers was investigated by nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometry (ESI-MS) analyses. A plausible mechanism of DMC catalyst-mediated copolymerization has also been proposed. Interestingly, the obtained low-molecular-weight (MW) aminic CO 2 -polyols displayed an intrinsic self-catalytic feature that is suitable for the preparation of rigid polyurethane foams without any external catalyst. This work demonstrates an efficient pathway to fix CO 2 into much more environmentally friendly polyols with low-volatility organic compounds.